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					TRANSPORTATION
RESEARCH DIGEST
         MARCH 2007




   ARIZONA TRANSPORTATION INSTITUTE

          e-mail jsemmens@cox.net
The contents of the Transportation Research Digest reflect the views of the authors who
are responsible for the facts and the accuracy of the data presented. The contents do not
necessarily reflect the official views or policies of the Institute
.




                                           2
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                       e-mail jsemmens@cox.net

                                             MARCH 2007

TO:            TRANSPORTATION PROFESSIONALS, MANAGERS, & POLICY MAKERS

FROM:          ARIZONA TRANSPORTATION INSTITUTE


         The volume of information on transportation issues, policies, technologies, and related
topics is huge. Not even the most well-read professional can keep up with everything that might be
useful to know. The Transportation Research Digest series is designed to expedite the transmission
of information by condensing and summarizing significant documents. Busy professionals or
managers may quickly obtain the gist of new developments and determine whether they need to see
the full document.

        The Transportation Research Digest is not meant to present definitive resolutions of
scientific or policy controversies, but contributions to the pursuit of knowledge and the debate of
issues. The intent is to be comprehensive rather than conclusive on the multitude of issues and
topics of concern to those working in the field of transportation. Readers are encouraged to obtain
the original document summarized in the Transportation Research Digest and subject the content to
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        Transportation professionals who would like to recommend documents to be summarized or
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       There is a database listing of all the previously published Transportation Research Digests
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mode can be provided on request. You may also access the database via the internet at
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http://www.dot.state.az.us/ABOUT/atrc/Publications/DocRev/TRDtest.htm

        A “Topic” code in the Table of Contents will help readers more quickly identify items of
interest. The topic codes are explained in the table below.

Code                Topic                          Code                       Topic
ADM                 Administration                 PLAN                       Planning
AIRP                Airports                       PRIV                       Privatization
AVIA                Aviation                       RAIL                       Railroads
BIKE                Bicycles                       RDSD                       Roadside
CON                 Construction                   ROW                        Right-of-Way
ECON                Economics                      SAFE                       Safety
ENV                 Environment                    STR                        Structures
FIN                 Finance                        TECH                       Technology
INOV                Innovations                    TOLL                       Toll Roads
MAIN                Maintenance                    TRAN                       Transit
MISC                Miscellaneous                  TRF                        Traffic
MVD                 Motor Vehicle Dept             TRK                        Trucking
PAVE                Pavement                       VEH                        Vehicles

       Requests or inquiries may be made via e-mail (jsemmens@cox.net).

       Thank you.




                                               4
TRANSPORTATION RESEARCH DIGEST
             ARIZONA TRANSPORTATION INSTITUTE
                                    e-mail jsemmens@cox.net

                                         MARCH 2007

                                   TABLE OF CONTENTS

Topic      Title                                                                             Pages

CON/       Laboratory Comparison of Several Tests for Evaluating the Transport                9-10
concrete   Properties of Concrete by D. Stephen Lane, Virginia Transportation Research
           Council, 530 Edgemont Road, Charlottesville, VA 22903 (Virginia Department
           of Transportation, 1401 E. Broad Street, Richmond, VA 23219) (June 2006)
           Several newly standardized test methods are available that directly measure the
           transport properties of concrete and should be useful in improving service-life
           models.

CON/       Use of Geophysics for Transportation Projects, NCHRP Synthesis 357 by Phil        11-12
geo-       C. Sirles, Sirles Consulting, LLC Lakewood, Colorado (Transportation
physics    Research Board, 500 Fifth Street, NW, Washington, DC 20001; (202) 334-
           3213; http://gulliver.trb.org/bookstore) (2006) The majority of survey
           respondents believe that using geophysics has the potential to save
           governmental agency funds and time, and reduce the risk associated with
           unknown subsurface conditions.
PAVE/      Aggregate Tests for Hot-Mix Asphalt Mixtures Used in Pavements, NCHRP             13-14
hot mix    Report 557 by Thomas D. White, Mississippi State University, John E.
asphalt    Haddock, Purdue University and Erza Rismantojo, PT Soilens (Transportation
           Research Board, 500 Fifth Street, NW, Washington, DC 20001; (202) 334-
           3213; http://gulliver.trb.org/bookstore) (2006) The object of this research was
           to use accelerated pavement testing techniques to conduct rutting, fatigue, and
           moisture susceptibility validation experiments.

PAVE/      Evaluation of the Influence of Tack Coat Construction Factors on the Bond         15-16
asphalt    Strength between Pavement Layers by Laith Tashman, Kitae Nam, and Tom
bonding    Papagiannakis, Washington State University, Center for Asphalt Technology,
           Pullman, WA 99164-2910; ph. 509-335-2513 (Federal Highway
           Administration, 400 Seventh St., S.W., Washington, D.C. 20590) (Aug 2006)
           Milling provided a significantly better bond at the interface between the
           existing surface and the new overlay.

PAVE/      Field Demonstration of Magnetic Tomography Technology for                         17-18
TECH       Determination of Dowel Bar Position in Concrete Pavement by Shabbir
           Hossain and Mohamed K. Elfmo, Virginia Transportation Research Council,
           530 Edgemont Road, Charlottesville, VA 22903 (Virginia Department of
           Transportation, 1401 E. Broad Street, Richmond, VA 23219) (Jun 2006) The
           MIT Scan-2 is a viable technology for construction quality control.
PAVE/      Use of the Digital Surface Roughness Meter in Virginia by David W.                19-20
rough-     Mokarem, Virginia Transportation Research Council, 530 Edgemont Road,
ness       Charlottesville, VA 22903 (Virginia Department of Transportation, 1401 E.
           Broad Street, Richmond, VA 23219) (July 2006) The purpose of this study was
           to obtain a preliminary indication of the suitability of the DSRM for measuring
           macrotexture of pavement surfaces.

PAVE/      Using Fiber-Optic Sensor Technology to Measure Strains Under the Asphalt          21-22
TECH       Layer of a Flexible Pavement Structure by Stephen R. Sharp, Khaled A. Galal,
           and Mohamed K Elfino, Virginia Transportation Research Council, 530
           Edgemont Road, Charlottesville, VA 22903 (Virginia Department of
           Transportation, 1401 E. Broad Street, Richmond, VA 23219) (Aug 2006)
           Installation of fiber-optic strain sensors (FOSS) at selected pavement sites
           would lead to more cost-effective pavement rehabilitation decisions.

PLAN/      Coordinated Freeway and Arterial Operations Handbook by Thomas Urbanik,           23-24
TRF        David Humphreys, Brian Smith, and Steve Levine, Applications International
           Corporation, 1710 SAIC Drive, MIS Tl-12-3, McLean, VA 22102 (Office of
           Operations Research and Development, Federal Highway Administration, 6300
           Georgetown Pike, McLean, Virginia 22101-2296) (May 2006) The purpose of
           this handbook is to provide direction, guidance, and recommendations for
           transportation managers, engineers, technicians, and planners on how to
           proactively and comprehensively coordinate freeway and arterial street
           operations.

PLAN/      Evaluation of Safety, Design, and Operation of Shared-Use Paths by J.E.           25-26
shared     Hummer, N.M. Rouphail, J.L. Toole, R.S. Patten, R.J Schneider, J.S. Green,
use path   R.G. Hughes, and S.J. Fain, Department of Civil, Construction, and
           Environmental Engineering, North Carolina State University, Raleigh, NC
           27695 (Office of Operations Research and Development, Federal Highway
           Administration, 6300 Georgetown Pike, McLean, Virginia 22101-2296) (July
           2006) The project objective was to produce a tool that can be used to evaluate
           the operational effectiveness of a shared-use path.

PLAN/      Performance and Accountability: Transportation Challenges Facing                  27-28
perform    Congress and the Department of Transportation (United States Government
           Accountability Office, 441 G Street NW, Room LM, Washington, D.C. 20548;
           Patricia Dalton at (202) 512-2834 or Daltonp@gao.gov;
           http://www.gao.gov/new.items/d07545t.pdf) (March 6, 2007) Improvements in
           data, performance measures, and evaluations are needed to determine whether
           programs are achieving intended results.




                                                6
PLAN/      Statewide Travel Forecasting Models, NCHRP Synthesis 358 by Alan                 29-30
travel     Horowitz, Center for Urban Transportation Studies, University of Wisconsin-
forecast   Milwaukee (Transportation Research Board, 500 Fifth Street, NW, Washington,
           DC 20001; (202) 334-3213; http://gulliver.trb.org/bookstore) (2006) Statewide
           models have proven to be versatile tools in statewide planning.

PLAN/      Traffic Data Collection Methodologies by Jim French and Millie French,           31-32
TRF        French Engineering, LLC, 114 Cooler Estate Rd., Smithfield. PA 15478
           (Pennsylvania Department of Transportation, Bureau of Planning and Research,
           Commonwealth Keystone Building, 400 North Street. 6th Floor, Harrisburg. PA
           17120) (Apr 2006) There appears to be good potential for using portable non-
           intrusive traffic data collection equipment.

SAFE/      Median Barrier Guidelines for Texas by Roger Bligh, Shaw-Pin Miaou,              33-34
medians    Dominique Lord, and Scott Cooner, Texas Transportation Institute, Texas
           A&M University System, College Station, Texas 77843-3135 (Texas
           Department of Transportation, Research and Technology Implementation
           Office P.O. Box 5080, Austin, Texas 78763-5080; 979.845.1734;
           http://tti.tamu.edu) (Aug 2006) High-tension cable barriers are generally more
           cost-effective than concrete barriers for the range of median widths > 20 ft.

STR/       Development and Implementation of Highway Structures Information System          35-36
database   for Wisconsin Department of Transportation by Scot M. Becker, W. Travis
           McDaniel, and Eric Baeverstad in Transportation Research Record 1958
           (Transportation Research Board, 500 Fifth Street, NW, Washington, DC 20001;
           (202) 334-3213; http://gulliver.trb.org/bookstore) (2006) HSI has provided a
           systematic approach to achieving asset management of structures in Wisconsin.

STR/       Interim Recommendations for the Use of Lithium to Mitigate or Prevent            37-38
alkali-    Alkali-Silica Reaction by Kevin J. Folliard, Michael D.A. Thomas, Benoit
silica     Fournier, Kimberly F. Kurtis, and Jason H. Ideker, The Transtec Group, Inc.,
reaction   1012 East 38½ Street, Austin, TX 78751 (Office of Infrastructure Research and
           Development, Federal Highway Administration, 6300 Georgetown Pike,
           McLean, Virginia 22101-2296) (July 2006) Combined use of lithium and SCMs
           (especially fly ash and slag) is recommended to reduce the economic impact of
           using lithium.

TECH/      A Qualitative Study of the Core Functions of Smart Traffic Centers at the        39-40
ITS        Virginia Department of Transportation by Gene Tey Shin, Virginia
           Transportation Research Council, 530 Edgemont Road, Charlottesville, VA
           22903 (Virginia Department of Transportation, 1401 E. Broad Street,
           Richmond, VA 23219) (June 2006) The presence of a fully developed Safety
           Service Patrol (SSP) greatly enhances the functionality of the STC.




                                                7
TRAN/      Bus Use of Shoulders, TCRP Synthesis 64 by Peter Martin, Wilbur Smith            41-42
bus on     Associates, San Francisco, California (Transportation Research Board, 500
shoulder   Fifth Street, NW, Washington, DC 20001; (202) 334-3213;
           http://gulliver.trb.org/bookstore) (2006) Bus use of highway shoulders to
           bypass congestion represents a low-cost and relatively quick strategy to
           improve bus running times and reliability.

TRAN/      Does it Deliver? Examining Whether Rail Transit Spurs Economic                   43-44
rail       Development in Privatization Watch by Ted Balaker (Reason Foundation, 3415
           S. Sepulveda Blvd., Suite 400, Los Angeles, CA 90034; 310/391-2245;
           http://www.reason.org/pwvol30no5.pdf) (Vol. 30, No. 5 2007) Rail investments
           generally have been ineffective and expensive, and the benefits do not justify
           the costs.

TRAN/      The Train Drain: Brookings Institution on Rail Transit in America in             45-46
rail       Privatization Watch by Robert W. Poole, Jr. (Reason Foundation, 3415 S.
           Sepulveda Blvd., Suite 400, Los Angeles, CA 90034; 310/391-2245;
           http://www.reason.org/pwvol30no4.pdf) (Vol. 30, No. 4, Fall 2006) The annual
           value of the benefits to users is much less than the annual cost to taxpayers.

TRF/       The Road More Traveled: Why the Congestion Crisis Matters More Than              47-48
congest    You Think and What We Can Do About It by Ted Balaker and Sam Staley
           (Reason Foundation, 3415 S. Sepulveda Blvd., Suite 400, Los Angeles, CA
           90034; (310) 367-6109; http://www.reason.org/road/) (2006) The book outlines
           10 steps that cities and states can take to reduce traffic significantly.




                                               8
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Laboratory Comparison of Several Tests for Evaluating the Transport Properties of Concrete by
D. Stephen Lane, Virginia Transportation Research Council, 530 Edgemont Road, Charlottesville,
VA 22903 (Virginia Department of Transportation, 1401 E. Broad Street, Richmond, VA 23219)
(June 2006)


Highlights                                                       The Rapid Chloride Permeability Test
 The Rapid Chloride Permeability Test has               has become a primary measure of concrete
  become a primary measure of concrete                   transport properties since its development in
  transport properties since its development in          the 1980s, largely because of the relative ease
  the 1980s.                                             and speed of the measurement with respect to
 Several newly standardized test methods are            the actual measurement of chloride penetration.
  available that directly measure the transport          The growing interest in service-life prediction
  properties of concrete and should be useful            models for concrete has created interest in
  in improving service-life models.                      methods that more closely reflect the actual
                                                         processes, absorption and diffusion, primarily
        The ability of fluids and ionic species to       involved in transport within concrete.
enter and move within concrete is a major
factor in determining its durability. As a               Conclusions
consequence, transportation agencies focus on                    The manner in which fluids and ionic
using concretes having low transport properties          species move into and within concrete is
to enhance service life. Although not always             largely a function of the saturation state of the
evident to the traveling public, this is                 concrete, with capillary actions predominating
nonetheless contrary to the agencies' prime              when the pore system is not saturated and ionic
objective: facilitating movement.                        diffusion predominating when the pore system
        Several mechanisms are involved in the           is saturated. Several newly standardized test
transport of fluids within concrete. Movement            methods are available that directly measure
into and through unsaturated concrete, a                 these transport properties of concrete and
common state for concrete with surfaces                  should be useful in improving service-life
exposed to the atmosphere, is largely controlled         models.
by absorption of the capillary pore system.                      ASTM C 1543 and ASTM C 1556 are
Where the pore system is saturated, diffusion            methods for measuring the apparent chloride
becomes the primary mechanism driving the                diffusion coefficient of concrete, a property
movement of ionic species. Pressure-driven               dependent on the maturity of the concrete. The
permeation is not a major factor regarding               repeatability of the ASTM C 1556 apparent
concrete durability in typical transportation            diffusion coefficient measurement was 27%.
system applications, but it may play a larger            The diffusion coefficient was not determined
role in deeply submerged elements such as                from the ASTM C 1543 data, because a
piles and tunnel linings where pressure heads            simplified sampling procedure was used rather
are large enough to drive flow through the               than the incremental profiling necessary for an
concrete.                                                accurate diffusion calculation.


                                                     9
        Because of the shorter duration and             chloride diffusion coefficient can be defined by
smaller specimen size, ASTM C 1556 offers               a logarithmic function.
advantages over ASTM C 1543 for
determination of apparent chloride diffusion            Recommendations
coefficient, especially where laboratory space                  VTRC should conduct ASTM C 1556
is limited.                                             and ASTM C 1585 tests on typical concrete
        ASTM C 1585 measures the absorption             mixtures to improve the understanding of the
rate of water into the capillary pore system of         relationships between these measures and the
concrete at a standard degree of saturation. The        electrical conductivity of concretes. Such a
rate of absorption slows after an initial (over         program should include maturity over an
several hours) period of absorption and two             extended period of time to assess how the
values, an initial and a secondary rate, are            relationships hold up over time. It should also
obtained. In these tests, the secondary rate            include variation in the ASTM C 1556 solution
remained stable through the 8-day test period,          concentration to examine how the driving
suggesting the test could be terminated after 1         concentration impacts the diffusion coefficient.
or 2 days. The repeatability of the initial and                 VTRC should initiate a program to
secondary absorption rates are 9.0% and 6.6%,           conduct ASTM C 1556, ASTM C 1585, and
respectively.                                           electrical conductivity tests on concretes that
        The relationship between the electrical         have been in service for an extended period of
conductivity of the concrete and the rates of           time. This information would add to the
absorption can be defined by an exponential             understanding of the transport properties of
function. The relationship between the                  mature concretes and provide the database
electrical conductivity and the apparent                necessary to incorporate these methods as
                                                        quality assessment tools in asset management
                                                        systems.




                                                   10
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Use of Geophysics for Transportation Projects, NCHRP Synthesis 357 by Phil C. Sirles, Sirles
Consulting, LLC Lakewood, Colorado (Transportation Research Board, 500 Fifth Street, NW,
Washington, DC 20001; (202) 334-3213; http://gulliver.trb.org/bookstore) (2006)


Highlights                                                among the respondents is "limited solicitation"
 The majority of survey respondents believe              or "sole-source" contracting.
  that using geophysics has the potential to                      The typical number of geophysical
  save governmental agency funds and time,                investigations conducted each year ranges from
  and reduce the risk associated with unknown             one to five for more than half of the
  subsurface conditions.                                  respondents. Contract values are predominantly
                                                          less     than     $10,000      per    geophysical
        This synthesis presents the state of the          investigation; however, there are agencies that
industry regarding the use of geophysics on               routinely use geophysics that will spend more
transportation projects. This use of geophysics           than $100,000 annually conducting geophysical
on geotechnical projects is increasing among              investigations. These agencies tend to carry
transportation agencies; however, the level of            large on-call Indefinite Delivery/Indefinite
use varies significantly from agency to agency.           Quantity-type contracts to easily access
For the purpose of this synthesis, geophysics is          qualified service providers for projects. Such
defined as the application of physical principles         contracts ranged from $300,000 per year to $5
to define geology and study earth (geo-)                  million for 3 years.
materials. Engineering geophysics is used to                      Between 50% and 60% of the agencies
evaluate natural and artificial foundation                and individuals completing the survey provided
materials-soil and rock; however, this synthesis          an experience rating of "good" to "excellent"
focuses on its application toward geotechnical            for their use of geophysics. However, several
problems.                                                 factors were identified as limitations to the
        Approximately 50% of the respondents              implementation of geophysics, including
to the project’s survey began implementing                difficult field instrumentation and software for
geophysics as part of their geotechnical                  data interpretation, poorly qualified service
investigations within the last 10 years; thus, for        providers, and subjective and non-unique
most agencies it is a relatively new                      results. However, the majority of respondents
investigation tool. Only a few agencies reported          indicated that inadequate understanding and
having in-house capabilities. Two agencies (of            knowledge of geophysics was the single
58) indicated that funds are allocated annually           greatest limitation.
for geophysics. The majority of agencies fund                     The results of this synthesis suggest that
geophysical investigations through their design           the majority of in-house geoscientists and
branches (departments) and procure the work               engineers      have    insufficient    knowledge
under contracts to architect and engineering              regarding the advantages of geophysics. As
firms as part of their larger geotechnical                experiences (e.g., case histories) are shared and
investigations or under lump-sum/fixed-price              educational      opportunities     provided    for
subcontracts. The primary mode of solicitation            transportation engineers and agencies, these


                                                     11
advantages will be better understood, which                    better characterization of the
could lead to more routine use of this                         subsurface.
technology on their projects. Because highway              6. The three greatest deterrents to using
engineers acknowledge this, the survey                         geophysics are (1) lack of
respondents requested that additional training                 understanding, (2) non-uniqueness of
resources be made available, including the                     results, and (3) lack of confidence.
development of a National Highway Institute                7. Three items that can overcome the
course. Although FHWA recently published                       deterrents are (1) training, (2)
and distributed the manual, Application of                     experience (and sharing thereof), and
Geophysical Methods to Highway Related                         (3) implementation of standards.
Problems, nearly 35% of the respondent                     8. Very few agencies allocate funds in
agencies were not aware of it, more than half of               their annual budgets specifically for
the agencies did not have it or were not sure if               geophysical investigations, and the
they did, and approximately 45% have not used                  majority of projects cost less than
it. Since its publication in 2004 as a web-based               $10,000.
document designed around problem solving                   9. Limited or sole-source solicitations are
and applications (not around geophysics), it is                the primary means of contracting
apparent that the effort to create the website                 geophysical providers; however, seven
and distribute the hard copy has not been fully                agencies are using large, on-call,
realized.                                                      multiyear contracts.
        The ten most important results derived             10. A successful-to-unsuccessful project
from this synthesis are:                                       ratio of 7:1 was shown to exist for the
                                                               set of entire responses.
   1. 68% of respondents do not use
      geophysics very often (i.e.,
                                                                Based on information gathered for this
      "occasionally"), and 45% of the
                                                        synthesis and previous discussions with
      agencies have used geophysics only in
                                                        hundreds of geotechnical engineers, it appears
      the past 10 years.
                                                        likely that as formal training occurs and
   2. 60% of the agencies mentioned that
                                                        successful    project    experiences    among
      there is an increase in their level of
                                                        transportation agencies increase, using trained
      effort to implement geophysics, with
                                                        in-house professionals and qualified service
      approximately 25% indicating an
                                                        providers, geophysics will become more widely
      increase of between 50% and 100%.
                                                        accepted and implemented as another tool for
   3. The three most commonly used
                                                        the transportation industry. This synthesis
      geophysical methods are (1) seismic,
                                                        determined that design and construction
      (2) ground penetrating radar, and (3)
                                                        engineers are beginning to appreciate the
      vibration monitoring.
                                                        benefits of geophysics through use and
   4. The top three geotechnical engineering
                                                        exposure over just the past 5 years. The
      applications for geophysics are (1)
                                                        majority of survey respondents believe that
      bedrock mapping, (2) mapping
                                                        using geophysics has the potential to save
      (characterizing) soil deposits, and (3)
                                                        governmental agency funds and time, and
      roadway subsidence.
                                                        reduce the risk associated with unknown
   5. The top three "greatest values" for using
                                                        subsurface conditions.
      geophysics are (1) speed of data
      acquisition, (2) cost benefits, and (3)




                                                   12
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Aggregate Tests for Hot-Mix Asphalt Mixtures Used in Pavements, NCHRP Report 557 by
Thomas D. White, Mississippi State University, John E. Haddock, Purdue University and Erza
Rismantojo, PT Soilens (Transportation Research Board, 500 Fifth Street, NW, Washington, DC
20001; (202) 334-3213; http://gulliver.trb.org/bookstore) (2006)


Highlights                                                        As part of their results, the NCHRP 4-
 UVA of both fine and coarse aggregates                 19 researchers recommended a follow-on
  reasonably predict rutting performance of              experiment for additional research to achieve
  HMA mixtures.                                          validation. The proposed research involved
 A minimum coarse aggregate UVA of 40%                  tests of both coarse and fine aggregate
  is recommended for traffic less than 100,000           uncompacted voids as well as the flat or
  Equivalent Single Axle Loads (ESAL).                   elongated particle test, 2:1 ratio (FOE21).
 A minimum coarse aggregate UVA of 45%                  These three tests were to be validated for their
  is recommended for traffic of 100,000                  ability to predict HMA rutting and fatigue
  ESAL and greater.                                      performances. Additionally, particle size
 A minimum fine aggregate UVA of 40% is                 analysis and methylene blue values (MBV) of
  recommended for traffic volumes less than              the HMA mixture aggregate fraction smaller
  500,000 ESAL.                                          than the 0.075-mm sieve (p0.075) were to be
 A minimum fine aggregate UVA of 45% is                 tested to validate their ability to predict rutting
  recommended for traffic volumes above this             in HMA mixtures. The researchers further
  level.                                                 suggested that the MBV of the fine aggregate
 An upper limit of 50% is recommended for               be validated for ability to predict moisture
  the FOE21 value for all traffic levels.                susceptibility of HMA. Finally, the results of
                                                         Micro-Deval (MDEV) and Magnesium Sulfate
        NCHRP Project 4-19, Aggregate Tests              Soundness (MGSO4) tests on aggregates were
Related to Asphalt Concrete Performance in               to be evaluated for predicting HMA toughness
Pavements,      recommended       a     set    of        and durability.
performance-related aggregate tests for                           The object of this research was to use
evaluating aggregates for use in hot-mix                 accelerated pavement testing techniques to
asphalt (HMA) pavements. Performance                     conduct the rutting, fatigue, and moisture
indicators considered in the research included           susceptibility validation experiments identified
permanent      deformation     resulting    from         in NCHRP Project 4-19. For each aggregate
laboratory traffic loading (both with and                test, a descriptive ranking indicating how well
without stripping), fatigue cracking, and                it relates to HMA performance is given. Also,
surface defects (e.g., raveling, popouts, and            an attempt has been made to suggest
potholes). The performance relationships were            appropriate tests for given combinations of
developed based on tests performed using the             climatic conditions, materials, and traffic loads.
Superpave Shear Tester (SST) and the Georgia                      A literature review was completed first
Loaded Wheel Tester (GLWT); however, the                 and was used to guide the research team in
relationships were not validated.                        selecting five coarse and six fine aggregates for


                                                    13
use in the study. The selected aggregates were                        Test results showed that the UVA of
tested and used in various combinations to                   both fine and coarse aggregates reasonably
produce five coarse-graded and six fine-graded               predict rutting performance of HMA mixtures.
mixtures that were then tested for rutting                   The FOE21 test also appears to predict HMA
characteristics in the accelerated loading                   rutting performance. These three tests also may
facility. The five coarse aggregates covered a               show trends in relation to HMA fatigue
wide array of aggregate types and properties;                performance, but the fatigue data are limited. A
each was combined with a common natural                      minimum coarse aggregate UVA of 40% is
sand to produce the five coarse-graded                       recommended for traffic less than 100,000
mixtures. The six fine aggregates also                       Equivalent Single Axle Loads (ESAL); a
represented various aggregate types and                      minimum coarse aggregate UVA of 45% is
properties; each of these was combined with a                recommended for traffic of 100,000 ESAL and
common coarse aggregate to produce the six                   greater. A minimum fine aggregate UVA of
fine-graded mixtures.                                        40% is recommended for traffic volumes less
         On completing the rutting tests, six of             than 500,000 ESAL; a minimum fine aggregate
the original eleven mixtures were chosen for                 UVA of 45% is recommended for traffic
accelerated testing to determine their fatigue               volumes above this level. An upper limit of
characteristics. The mixtures were chosen so as              50% is recommended for the FOE21 value for
to represent a wide range of aggregate and                   all traffic levels.
mixture characteristics. Although the rutting                         The MDEV and MGSO4 tests also
testing proceeded well, problems were                        appear reasonably predictive of HMA
encountered with the fatigue testing.                        performance. Maximum values of 15 and 20%
Construction of the conventional flexible                    for MDEV and MGS04, respectively, are
pavement sections in the accelerated loading                 recommended.
facility proved to be more difficult than                             Although the particle size analysis of
anticipated. Lack of temperature control in the              the p0.075 material and the MBV tests appear
facility also made it difficult for the test slabs to        to have some performance predictive ability,
exhibit fatigue signs during the test, at least two          the relationships were weak. Neither of these
mixtures exhibited excessive rutting before                  tests is recommended for routine aggregate
showing signs of fatigue.                                    specifications.
         In addition to the rutting and fatigue                       Finally, research is suggested to gather
tests, five additional HMA mixtures were                     additional information about the relationship
designed using five of the six fine aggregates               between the recommended aggregates tests and
and one common coarse aggregate. These                       HMA fatigue performance. Because the
mixtures were placed in the accelerated loading              relationship between laboratory and in-service
facility and tested for rutting in the presence of           fatigue typically is a scaling factor, adequate
moisture to determine if the aggregate tests                 information can be obtained from a laboratory
predict moisture susceptibility in HMA                       experiment. Full-scale testing is not required.
mixtures.




                                                        14
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Evaluation of the Influence of Tack Coat Construction Factors on the Bond Strength between
Pavement Layers by Laith Tashman, Kitae Nam, and Tom Papagiannakis, Washington State
University, Center for Asphalt Technology, Pullman, WA 99164-2910; ph. 509-335-2513 (Federal
Highway Administration, 400 Seventh St., S.W., Washington, D.C. 20590) (Aug 2006)


Highlights                                                       The objective of this study was to
 Milling provided a significantly better bond           investigate the factors that influence the
  at the interface between the existing surface          adhesive bond provided by the tack coat at the
  and the new overlay.                                   interface between pavement lifts. This study
                                                         also aimed at evaluating potential quality tests
        A tack coat is a light application of an         for tack coat application.
asphaltic emulsion between pavement lifts,
most commonly used between an existing                   Conclusions
surface and a newly constructed overlay. The                     Three tack coat construction quality
role of a tack coat is to provide adequate               tests were evaluated. These tests were the
adhesive bond between pavement layers. The               Florida Department of Transportation (FDOT)
inadequacy or failure of this bond causes                Shear Tester, Torque Bond test, and University
slippage, which results in a significant                 of Texas at El Paso (UTEP) Pull-Off test. The
reduction in the strength of the pavement                results from each test are summarized.
structure, making it more susceptible to
cracking, rutting, and potholes.                         FDOT Shear Tester
        A tack coat is considered as a simple,             o Milled sections had significantly higher
relatively inexpensive, yet essential step in the             shear strength than non-milled sections.
pavement construction process. However, there              o Curing time was an insignificant factor.
is currently a lack of unified guidelines on the           o The absence of tack coat did not affect
construction practices and quality control/                   the shear strength for the milled
acceptance (QC/QA) of tack coats. In a recent                 sections, whereas it significantly did so
study conducted by Washington State                           for the non-milled sections.
Department of Transportation (WSDOT), field                o Increasing the residual rate did not
cores were extracted to analyze the mode of                   significantly improve the shear strength
cracking failure. Despite the fact that WSDOT                 for either milled sections or non-milled
requires tack coat on all hot mix asphalt                     ones. However, milled sections were
(HMA) paving surfaces, approximately one                      more sensitive to increasing the residual
third of the cores that exhibited "top-down                   rate compared to non-milled sections.
cracking" debonded at the interface between                o The shear strength at the interface was
the existing pavement and the subsequent                      not affected by the location (wheel path
overlay during extraction. These bond failures                vs. middle of lane ).
raise concerns about the adequacy of the
adhesive bond achieved under current
pavement construction practices.


                                                    15
Torque Bond Test                                        measures it in torsional shear, whereas the
   o Milled sections had significantly higher           UTEP Pull-Off test measures the tensile
      strength than non-milled ones.                    strength of the tack coat. The FDOT Shear
   o Curing time had no effect on the                   Tester seems to better simulate the state of
      strength at the interface.                        stress encountered in the field (shear stress) that
   o The absence of tack coat significantly             causes the de-bonding at the interface between
      decreased the strength at the interface           pavement layers.
      for non-milled sections.                                  Overall, milling provided a significantly
                                                        better bond at the interface between the existing
UTEP Pull-Off Test                                      surface and the new overlay. For milled
  o Non-milled sections had a higher Pull-              sections, the absence of tack coat did not
     Off strength than milled sections. This            significantly affect the bond strength at the
     was the only significant factor.                   interface. This was not true for the non-milled
                                                        sections, where the absence of tack coat
         Generally, the results from the FDOT           severely decreased the bond strength (there was
Shear Tester were consistent with those in the          no bond at all). Curing time had minimal effect
literature. The experimental data from the              on the bond strength at the interface. Residual
Torque Bond test were highly censored, and              rates in the range of 0.02 - 0.07 gal/yd2 did not
thus provided limited observations. This was            significantly change the bond strength at the
despite the fact that the test was performed            interface. Equipment tracking did not occur to
according to the British Board of Agrément              the extent expected during the experiment,
(BBA) standards. As a result, only a regression         hence the coring location did not significantly
based Expected Life type of analysis could be           affect the bond strength at the interface.
conducted.      Nonetheless,      the    limited                It should be noted that these
observations from the Torque Bond test were             conclusions were drawn based on the initial
consistent with those from the FDOT Shear               results from this study, which only used one
Tester. The results from the UTEP Pull-Off test         type of tack coat and one HMA mixture for the
were generally the opposite of the other two            existing surface as well as the new overlay.
tests. This was attributed to two factors that          These results could be different if other types
might have affected the test results: 1) lack of        of tack coat and HMA mixtures were used.
adhesion between the contact plate and the tack         Also, this study was conducted in one day
coat on milled sections, and 2) performing the          where the weather condition remained almost
test in a chronological order starting with the         unchanged. The results could differ if the
lowest residual rate.                                   experiment was conducted under different
         The three tests have different testing         weather conditions (effect of moisture and/or
mechanisms. The FDOT Shear Tester measures              temperature).       Furthermore,        long-term
the bond strength of the interface between the          performance data have not been collected at
two lifts in shear, the Torque Bond test                this time.




                                                   16
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Field Demonstration of Magnetic Tomography Technology for Determination of Dowel Bar
Position in Concrete Pavement by Shabbir Hossain and Mohamed K. Elfmo, Virginia
Transportation Research Council, 530 Edgemont Road, Charlottesville, VA 22903 (Virginia
Department of Transportation, 1401 E. Broad Street, Richmond, VA 23219) (Jun 2006)


Highlights                                                        The repeatability of the measurement by
 The MIT Scan-2 yielded fairly accurate                  the MIT Scan-2 was very good, with an overall
  measurements for joints without any                     maximum difference of 8 mm (0.3 in) between
  interference.                                           two replicate measurements. The maximum
 The MIT Scan-2 is very user-friendly.                   difference between two replicate measurements
 The MIT Scan-2 is a viable technology for               was as low as 2 mm for depth and vertical
  construction quality control.                           misalignment measurements. The overall
                                                          maximum standard deviation of 2.78 mm (0.11
        The purpose of this study was to                  in) is comparable with the FHWA standard
demonstrate and evaluate the use of magnetic              deviation of 3 mm (0.12 in).
tomography technology through use of the                          The MIT Scan-2 is very user-friendly.
Magnetic Imaging Tools (MIT) Scan-2. The                  Although data analysis is more involved, actual
main objective was to measure the alignment of            field operation is simple and easy to learn. The
dowel bars in a selected number of jointed                challenges for field operation are traffic control
plain concrete pavements (JPCP) in Virginia               and the tedious processes of manual setup of
and demonstrate the applicability of this new             the device for every joint.
technology. The device was also used to                           Most complications in the data analysis
evaluate the capability to measure the depth of           are due to signal interferences for several
longitudinal steel in continuously reinforced             reasons, including the following:
concrete pavement (CRCP).                                     o signal loop
        The MIT Scan-2 successfully scanned                   o dowels deeper than 200 mm (8 in)
both basket and dowel bar inserter (DBI) dowel                o exposed dowel bar
bars using bare bar calibration.                              o presence of tie bar or any other foreign
        The MIT Scan-2 yielded fairly accurate                    metal nearby
measurements for joints without any                           o excessive misalignment in general
interference, and the deviation from the actual               o apparent depth of dowels shallower than
orientation was less than 10 mm (0.4 in).                         100 mm (4 in) in the field results.
Dowel bars were successfully located.
Although the data are quantitatively unreliable                   The close spacing and shallow depth of
for situations where signal interference is               the reinforcing steel in continuously reinforced
possible, a qualitative observation is possible in        concrete pavement made using the MIT Scan-2
most cases, at least for the part of the                  to determine the depth of longitudinal
unaffected joint. The real challenge is to find a         reinforcement impossible.
situation without much signal interference in
the field.


                                                     17
        The interference from the reinforcing                    For l lane-mile (5,280 ft, 1.61 km),
steel in jointed concrete pavement made using            assuming a joint spacing of 15 ft (4.57 m), the
the MIT Scan-2 impossible in such situations.            number of joints is 352 per mile. If it is
                                                         assumed that 5% of the joints (18 joints) have
Recommendations                                          severe misalignments that were not detected,
        VDOT's Asset Management Division or              these joints will eventually be replaced because
the district pavement management sections                of locking, spalling, and lack of load transfer
should include the collected data and analysis           efficiency between the jointed concrete slabs.
in the respective project database for future            The minimum replaced area of concrete per
consideration      during     evaluation    and          joint is recommended to be 6 ft by 12 ft,
rehabilitation.                                          resulting in 8 yd2 of concrete placement,
        VDOT's Materials Division should                 leading to a total replacement of 144 yd2/ mile.
consider the MIT Scan-2 a viable technology              The cost of joint replacement is estimated at
for construction quality control. For VDOT to            $300/yd2, giving a total of $43,200 per lane-
be able to use this technology, the signal               mile. Considering that 50% of VDOT's total
interference needs to be minimized. One way to           jointed concrete pavement is estimated at about
minimize the interference is to establish a              300 lane-miles of JPCP, this represents a
practice of cutting the shipping wire for the            savings of $13 million for the entire JPCP
dowel basket.                                            system during its service life. If the analysis is
        VDOT's Materials Division should use             repeated     assuming      only     2.5%     joint
this technology in conjunction with other                deterioration, the cost savings can be estimated
technologies such as the falling weight                  at $6.5 million for the entire JPCP system.
deflectometer, ground-penetrating radar, and             Based on these assumptions, the potential
video logging to allow a complete evaluation             savings can be clearly realized from
on the project level and forensic analysis.              implementing this new technology. This does
                                                         not include the user cost, which may also be
Benefits and Costs Assessment                            significant. In addition, capturing the
        The value of the MIT Scan-2 is in its            misaligned dowel bars during construction
non-destructive approach and its ability to work         would obligate the contractor to bear the repair
on recently placed and hardened JPCP. As a               cost. Experience has also shown that when
quality assurance tool for new JPCP                      VDOT has a quality assurance technology, the
construction or evaluation for rehabilitation, it        contractor's        performance         improves
can accurately pin point the degree of                   tremendously, since VDOT can identify the
misalignment. The potential (projected)                  problem early on during construction. This
cost/benefit of using such technology can be             leads to a savings in both time and money.
demonstrated in the following example, based
on traditional experiences with JPCP.




                                                    18
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Use of the Digital Surface Roughness Meter in Virginia by David W. Mokarem, Virginia
Transportation Research Council, 530 Edgemont Road, Charlottesville, VA 22903 (Virginia
Department of Transportation, 1401 E. Broad Street, Richmond, VA 23219) (July 2006)


Highlights                                                (VTRC) and others has demonstrated the
 There is a good correlation among the                   validity of the CT meter and the sand patch
  results of DSRM, sand patch, and CT meter               test. The applicability of the DSRM for use in
  testing.                                                characterizing highway surface texture has yet
 The DSRM measuring technique appears to                 to be determined.
  be more efficient than the sand patch test for                  The purpose of this study was to obtain
  taking measurements when there is a time                a preliminary indication of the suitability of the
  constraint or inadequate lighting.                      DSRM for measuring macrotexture of
                                                          pavement surfaces. This assessment was
        Pavement surface texture is measured in           accomplished through comparison of the
a variety of ways in Virginia. Two methods                DSRM and the traditional CT meter and sand
commonly used are the "sand patch" test and               patch test procedures. This comparison was
the circular track (CT) meter. The first                  conducted using various concrete and asphalt
technique is performed in accordance with                 pavement surfaces on Virginia roadways and at
ASTM E 965, Standard Test Method for                      the Virginia Smart Road facility. A more
Measuring Pavement Macrotexture Depth                     detailed comparison of the three procedures
Using a Volumetric Technique. The second                  will require a much larger database.
technique is performed in accordance with                         From the data obtained in this study,
ASTM E 2157, Standard Test Method for                     there appears to be a good correlation among
Measuring Pavement Macrotexture Properties                the results of DSRM, sand patch, and CT meter
Using the Circular Track Meter. Both methods              testing. The DSRM and sand patch methods
can be used to measure surface texture in a               measure a smaller area than does the CT meter,
localized area such as a bridge deck, stretches           with the CT meter employing a rotating arm.
of pavement that are a discrete length, and               These differences in areas measured could
situations in which live traffic is not a concern.        produce different texture results. One way to
        The CT meter and the sand patch tests             reduce such differences would be to take a
were developed specifically for characterizing            series of DSRM and sand patch measurements
highway surface textures. At least one device             that cover the entire area of the CT meter
with similar capabilities, the Digital Surface            measurement. The average of these series of
Roughness Meter (DSRM), was developed for                 measurements might then be closer to the CT
measuring "smoothness" of other constructed               meter measurement. The use of the DSRM and
and fabricated finishes. The device is an optical         CT meter also reduces the probability of human
laser-based imaging system that uses a laser              error. The sand patch test is exposed to a
profiling line to measure roughness.                      greater probability of human error; it is a test
        Previous work performed by the                    that cannot be performed quickly. If the test is
Virginia Transportation Research Council                  performed too quickly, the accuracy is


                                                     19
compromised. The DSRM is a better device to               Conclusions
use when there is a time constraint. The test can                 In situations with no time constraints
be performed quickly without compromising                 where the testing surface is uniform, there is a
accuracy.                                                 good correlation among results of the DSRM,
        In situations with no time constraint,            sand patch, and CT meter measuring
lighting is good, and the test surface is uniform,        techniques.
there is a good correlation among the three                       The DSRM measuring technique
testing techniques. All three are easy to                 appears to be more efficient than the sand patch
perform. As for limitations, the sand patch test          test for taking measurements when there is a
can produce a lot of variability. The test                time constraint or inadequate lighting.
appears to be user-dependent with a lot of
variability among users. With the DSRM and                Recommendations
CT meter, there is less variability among users.                 Because the DSRM device is expensive
However, the equipment associated with the                and requires two people to operate, it is not
DSRM and CT meter is more costly than a sand              recommended at this time that the device be
patch kit. The developers of the DSRM are in              used as a replacement for the sand patch
the process of developing a newer version of              technique for measuring macrotexture of
the device that can be operated by one person.            pavement surfaces.
This would enhance the efficiency of the device                  In the event a new lower cost single-
in the field in the sense that only one person            operator DSRM device is developed, VTRC
would be needed to take the measurement and               should compare its efficiency in taking field
collect the data. As it stands now, the device            measurements with that of the sand patch test.
requires two people to operate: one to take the
measurement, and the other to collect the data            Benefits and Costs Assessment
through the laptop computer.                                      The cost of the equipment associated
        In the event a new DSRM is developed,             with the three measurement techniques
there is a current application that may be well           investigated in this report varies by device. The
suited for this device. The Virginia Department           CT meter is the most expensive, with a cost of
of Transportation has a special provision for the         approximately $20,000. The DSRM has a cost
planing of asphalt concrete pavement, which               of approximately $9,500, which includes the
specifies a mean texture depth (MTD) for a                device and software but not the laptop
planed surface that is to be exposed to traffic on        computer. However, the equipment and
limited access roadways. The specified MTD is             software are compatible with most computers.
currently measured using the sand patch test in           The sand patch test kit can be fabricated for
accordance with ASTM E 965. If the single-                less than $200.
operator device is developed, it could be used                    The benefits of the CT meter and the
for taking the measurements required by this              DSRM are that there is a smaller probability of
special provision. The average time required              variability than with the sand patch testing. The
for a single sand patch test is approximately 5           use of the CT meter and DSRM would most
minutes; the single-operator DSRM test could              likely increase the accuracy and repeatability of
be performed in less than 1 minute. The new               the measurements. Another benefit associated
device would have the potential to decrease the           with the DSRM is that the tests can be
time required to measure surface texture for              performed under field conditions where there
this special provision.                                   are time constraints more easily than with sand
                                                          patch testing.




                                                     20
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Using Fiber-Optic Sensor Technology to Measure Strains Under the Asphalt Layer of a Flexible
Pavement Structure by Stephen R. Sharp, Khaled A. Galal, and Mohamed K Elfino, Virginia
Transportation Research Council, 530 Edgemont Road, Charlottesville, VA 22903 (Virginia
Department of Transportation, 1401 E. Broad Street, Richmond, VA 23219) (Aug 2006)


Highlights                                               results were very close to the measured
 Multi-layer elastic (MLE) analysis can be              deflection under dump truck and FWD
  used to validate and calculate the strains in          loadings.
  asphalt pavement sections.                                     The results show that MLE analysis can
 Installation of fiber-optic strain sensors             be used to validate and calculate the strains in
  (FOSS) at selected pavement sites would                asphalt     pavement     sections.    Long-term
  lead to more cost-effective pavement                   performance monitoring is continuing, and the
  rehabilitation decisions.                              study will be repeated after FOSS placement in
                                                         new HMA pavement sections.
        In this study, a flexible pavement                       Understanding the behavior of asphalt
system was instrumented using fiber-optic                pavement under repeated traffic loads can
strain sensors (FOSS). The purpose of this               result in an optimized design, thus reducing the
study was to demonstrate the feasibility of a            rehabilitation costs associated with premature
FOSS installation, monitor the long-term                 failures or the higher costs associated with
strains under repeated traffic loading, and              conservative asphalt pavement designs. The in-
compare the measured strains with the                    situ strains can be used to calibrate
calculated ones from multi-layer elastic (MLE)           mechanistic-empirical pavement design guide
analysis.                                                (MEPDG) performance models for local
        MLE analysis was performed before                conditions so that measurements can better
and after FOSS installation to monitor strains           predict the life of pavement layers and the
during and after construction. In-situ strains           layers that will need replacement. The
during construction under the hot-mix asphalt            installation of FOSS at selected pavement sites
(HMA) delivery truck, paver operations, and              that represent the typical pavement designs
roller operations were compared to the results           across the state would allow for the
of theoretical MLE analysis. In addition, in-situ        development       of     accurate      statewide
strains after construction under dump truck and          mechanistic-empirical performance models,
falling weight deflectometer (FWD) loadings at           which would lead to more cost-effective
multiple load levels were compared to the                pavement rehabilitation decisions.
results of theoretical and in-situ MLE analysis.
        The in-situ strain under construction            Recommendations
was at least 50 fold that obtained with MLE                     1. The Virginia Transportation Research
analysis. The FOSS were sensitive enough to              Council (VTRC) and VDOT's Materials
collect strain measurements during construction          Division should use FOSS for further
at very high construction temperatures and               evaluation in future pavement installations
moisture conditions. Further, the MLE analysis           using different pavement types and layers.


                                                    21
        2. VTRC and VDOT's Materials                    rehabilitation costs associated with premature
Division should use MLE analysis to predict             failures or the higher costs associated with
pavement strains at critical pavement locations         conservative asphalt pavement designs.
when designing or evaluating pavement                           For example, pavement management
structures.                                             data show that more than 90% of Virginia's
        3. VTRC should use FWD deflection               roadways are constructed and/or rehabilitated
testing to evaluate the FOSS that will be placed        using asphalt pavements. Reducing the
at other pavement sites. Dynamic (load history)         pavement thickness by 0.5 inch can save an
and peak deflection data are necessary for              estimated $15,000 per lane mile in materials
future evaluation of FOSS.                              cost alone. Over-designing can quickly increase
        4. VTRC should use three-dimensional            the materials cost for VDOT during paving. If
finite element modeling for further evaluation          the pavement is under-designed, premature
of the MLE analysis presented in this research          failure of the flexible pavement system could
study.                                                  result, which would lead to maintenance at an
                                                        earlier date than expected.
Benefits and Costs Assessment                                   It is anticipated that the results of this
       Premature pavement failures can result           research study will provide pavement engineers
from designing and constructing asphalt                 with a better understanding of the effects of
pavements that are too thin. On the other hand,         dynamic loading (repeated traffic loads) on a
conservative asphalt pavement designs result in         pavement structure. This information will be
thick asphalt pavements with higher                     useful in validating future designs. It will also
construction costs. Understanding the behavior          provide a novel technique for evaluating new
of asphalt pavement under repeated traffic              pavements in the field with minimal disruption
{dynamic) loads can result in an optimized              to the paving process.
asphalt pavement design, thus reducing the




                                                   22
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Coordinated Freeway and Arterial Operations Handbook by Thomas Urbanik, David Humphreys,
Brian Smith, and Steve Levine, Applications International Corporation, 1710 SAIC Drive, MIS Tl-
12-3, McLean, VA 22102 (Office of Operations Research and Development, Federal Highway
Administration, 6300 Georgetown Pike, McLean, Virginia 22101-2296) (May 2006)


Highlights                                                        The purpose of this handbook is to
 The purpose of this handbook is to provide              provide       direction,      guidance,         and
  direction, guidance, and recommendations                recommendations for transportation managers,
  for transportation managers, engineers,                 engineers, technicians, and planners on how to
  technicians, and planners on how to                     proactively and comprehensively coordinate
  proactively and comprehensively coordinate              freeway and arterial street operations. There are
  freeway and arterial street operations.                 many guidance documents on how to manage
 Significant decreases in traffic delay can be           and      operate      transportation      facilities
  achieved.                                               individually, but this document is a first-of-a-
                                                          kind because it focuses on how to coordinate
        Traffic congestion is increasing                  the operations of different facility types that are
significantly throughout the United States.               typically operated by separate organizational
Further, the transportation community realizes            entities with separate missions. To support the
there is no one proven way to fix the                     goal and purpose of this document, specific
congestion problem and that a comprehensive               objectives include:
approach of multiple congestion-reducing                      o Discuss the benefits of coordinated
strategies is needed. One of these strategies is                freeways and arterials (CFA) operations
to operate the existing roadway system more                     and why taking a coordinated approach
efficiently or, in other words, to get more out of              benefits both users and managers of the
what already exists.                                            transportation system.
        This handbook is not just about using                 o Explain how to take a broad, regional
system management strategies to operate                         view of coordinating freeway and
freeways and arterials more efficiently; rather,                arterial streets before making plans and
the focus of this guide is on operating freeways                procedures for specific corridors.
and adjacent arterials together in a coordinated              o Describe how to develop a regional
manner that treats these roadways not as                        corridor management plan to support a
separate entities, but as an interconnected                     broad, regional view of coordinated
traffic operations corridor. This is how                        corridor operations.
transportation users view and use these                       o Describe a framework for planning and
roadways. Users will often, for example, divert                 implementing coordinated plans and
from a freeway to an adjacent arterial during a                 procedures for a single freeway and
freeway incident because they realize the                       arterial corridor.
adjacent arterial will get them to their                      o Address the institutional challenges
destination more efficiently in this scenario.                  inherent in coordination and suggest
                                                                ways to overcome these barriers.


                                                     23
   o Define the range of possible operations                work zone management, planned
     strategies that can be used to address                 special events management, and day-to-
     CFA operations, such as traveler                       day operations.
     information, traffic management and                  o Discuss the intelligent transportation
     control, and information and resource                  system (ITS) technologies and
     sharing.                                               components used to support coordinated
   o Discuss how to package the operations                  operations and how to perform an ITS
     strategies into operations plans and                   needs assessment to support the
     procedures for different response                      development of specific coordinated
     scenarios.                                             plans and procedures.
   o Illustrate how coordinated plans and                 o Present a hypothetical application of
     procedures can be developed for                        state-of-the-art ITS in a regional area
     specific opportunities for coordination,               with multiple corridors to demonstrate
     including traffic incident management,                 real-time dynamic CFA operations.

                               Examples of Benefits of CFA operations
Location (Date)                       Background                                   Impacts
M-S Corridor,      Field deployment of adaptive signal control,
                                                                    Traffic volume: no change. Travel
Glasgow, Scotland  ramp metering, and DMS messages to balance
                                                                    time: 13% decrease.
(1997-1998)        traffic loads through corridor.
                   Simulated deployment of alternative corridor
                   operations plans (signal timing plans, ramp      Travel time: 2-30% decrease. Stop
Anaheim, CA (2000)
                   metering plans, DMS messages, route diversion time: 15-56% decrease.
                   plans) during nonrecurring congestion.
                                                                    Freeway management only: 16.2%
                   Simulated deployment of corridor operations
San Antonio, TX                                                     delay reduction. Integrated freeway
                   plans for integrating incident management,
(2000)                                                              and arterial management: 19.9%
                   DMS messages, and signal timing plans.
                                                                    delay reduction.
                   Simulated deployment of integrating arterial and Freeway only ATIS: 1.5% delay
Seattle, WA (2000) freeway advanced traveler information systems reduction. Freeway plus arterial
                   (ATIS) in north 1-5 corridor.                    ATIS: 3.4% delay reduction.




                                                   24
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Evaluation of Safety, Design, and Operation of Shared-Use Paths by J.E. Hummer, N.M.
Rouphail, J.L. Toole, R.S. Patten, R.J Schneider, J.S. Green, R.G. Hughes, and S.J. Fain,
Department of Civil, Construction, and Environmental Engineering, North Carolina State
University, Raleigh, NC 27695 (Office of Operations Research and Development, Federal Highway
Administration, 6300 Georgetown Pike, McLean, Virginia 22101-2296) (July 2006)


Highlights                                                use justifies, there is a waste of money that
 The project objective was to produce a tool             could otherwise have been used to construct
  that can be used to evaluate the operational            more miles of trail elsewhere. If the designer
  effectiveness of a shared-use path.                     specifies a trail that proves to be too narrow for
                                                          the future volume and mix of users, there will
        Shared-use paths are paved, off-street            be more user conflicts and collisions, greater
travel ways designed to serve non-motorized               unhappiness among users, and the need to
travelers. Shared-use paths are gaining                   consider expensive trail widening.
popularity in two different ways in recent years                  At the present time, conventional design
in the United States. First, there are many more          manuals do little to help designers resolve their
paths and many more miles of paths being                  dilemmas. The classic procedure bases LOS on
created. Second, shared-use paths are attracting          the estimated number of meetings and passings
an increasingly greater amount of use. Some               for bicyclists. This is an attractive framework
urban trails attract thousands of users per hour          that could help designers. There can be little
during peak periods and some are experiencing             debate that, in general, paths where bicyclists
rush hours and traffic jams. Trail managers are           must make more meetings and passings should
becoming increasingly concerned about user                be less desirable than trails with fewer meetings
conflicts and injuries, and some are also                 and passings.
concerned that potential users are deciding not                   The overall project objective was the
to come out and use a trail because of                    production of a tool that professionals can use
crowding.                                                 to evaluate the operational effectiveness of a
        The design of a new path or a path to be          shared-use path, given a traffic forecast or
rebuilt is thus an increasingly important                 observation at an existing path along with some
activity. During the design of every shared-use           geometric parameters. In particular, the
path, someone eventually asks; "How wide                  objective was to produce a tool that overcomes
should this pathway be?" That question nearly             the major limitations in the current LOS
always raises even more questions: What types             procedure noted above. The desired procedure
of users can we reasonably expect? When will              emerging from this project would:
we need to widen the path? Do we need to                     o   Be calibrated and validated.
separate different types of users from each                  o   Be based on U.S. data.
other? These are very difficult questions for                o   Have LOS criteria based on user input.
designers who face that classic design dilemma               o   Include more modes.
of overbuilding versus obsolescence. If the                  o   Include the ability to change key
designer specifies a trail to be wider than future               parameters such as mean speeds.


                                                     25
   o Account for delayed passing.                         chose to use the moving-bicycle method to
   o Analyze the full range of existing and               collect these variables. The database included a
     possible path widths.                                wide array of volumes and speeds for five
   o Be in a form ready for use by path                   different major user groups. The major analysis
     designers.                                           of the database was to use the theory described
                                                          above to predict of the number of meetings and
Conclusions                                               passings for each run, and to compare that
        The project made two significant                  prediction to the number of meetings and
advances in the theory of traffic flow on                 passings counted in the field. Results showed
shared-use paths. First, the authors extended             that the prediction matched the field count
the previous method to other modes, other                 fairly well at most sites.
speed distributions, and passive passings. A                       The third major part of this effort was to
passive passing is an occasion when the test              collect data on user perceptions of multi-use
bicyclist is passed by a faster path user.                trail designs and operations to help set the LOS
Second, the team developed a way to calculate             criteria. Analysis showed that there was a
the number of delayed passings. These are                 strong relationship between the number of
times when the test bicyclist would arrive                meetings and passings and enjoyment, and that
behind a slower path user and not be able to              path width was the primary geometric variable
pass because of the lack of an adequate gap in            that affected user perception.
the next lane to the left (oncoming or same                        The most important accomplishment of
direction). Obviously, delayed passings are               the project team was the production of a new
undesirable for bicyclists since they then have           method to estimate the LOS for a shared-use
to slow down and then probably expend energy              path. The procedure uses simple inputs that
accelerating when an adequate gap does appear.            should be readily available to path designers,
Delayed passings are also critical because they           including one-way user volume, mode split,
are so highly related to path width. Prior to this        path width, and the presence or absence of a
project, there were some delayed passing                  centerline. The procedure uses the theory that
calculations in the literature related to two-lane        we developed and validated to predict the
highway operation, etc.; however, there was               number of meetings and passings that will
nothing in the literature related to shared-path          occur; it uses a number of default values based
operation. The new theory will estimate                   on data we collected if local values were not
delayed passings of various modes for two-                available. The LOS is based primarily on the
lane, three-lane, and four-lane paths.                    model of user satisfaction that emerged from
        The objective of the operational data             the perception study. The output from the LOS
collection portion of this project was to collect         procedure is a traditional A through F grade
the field data needed to calibrate and validate           with which users can judge the performance of
the LOS model for shared-use paths. To                    an existing path or a design alternative. The
calibrate and validate an LOS model, the main             project team has also produced software to
variables were meetings and desired and actual            calculate the LOS automatically, greatly easing
passings by path users, and the speeds and                the burden on future users.
volumes of the path user groups. The team




                                                     26
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Performance and Accountability: Transportation Challenges Facing Congress and the
Department of Transportation (United States Government Accountability Office, 441 G Street
NW, Room LM, Washington, D.C. 20548; Patricia Dalton at (202) 512-2834 or Daltonp@gao.gov;
http://www.gao.gov/new.items/d07545t.pdf) (March 6, 2007)


Highlights                                               significant and expected to worsen. However,
 Improvements in data, performance                      federal funding levels are not linked to specific
  measures, and evaluations are needed to                performance-related goals and outcomes,
  determine whether programs are achieving               resulting in limited assurance that federal
  intended results.                                      funding is being channeled to the nation’s most
                                                         critical mobility needs. Furthermore, federal
        Financing mechanisms for the nation’s            funding is often tied to a single transportation
transportation system are under stress. The              mode, which may limit the use of federal funds
efficiency of the nation’s transportation                to finance the greatest improvements in
infrastructure is threatened by increasing               mobility. It is also unlikely that mobility can be
demand for transportation services, and                  enhanced unless major modes—air, highway,
revenue from traditional funding mechanisms              rail, transit, and water—are well connected.
may be unable to keep pace at current tax rates.         However, intermodal connections, such as
Revenues to support the Highway Trust                    multimodal passenger terminals and roads that
Fund—the major source of federal highway                 link freight terminals and major highways, are
and transit funding—are eroding, with recent             among the transportation system’s weakest
estimates forecasting a negative balance of              links.
more than $14 billion by the end of fiscal year                   The department is implementing a
2012. For aviation, there is concern that with           number of new initiatives aimed at mitigating
the current funding system, the costs of                 congestion, including providing funds to local
providing and modernizing air traffic control            governments to test innovative ideas for
services     might      increase    without     a        curbing congestion and new funding for
corresponding increase in revenues collected             projects that have national or regional benefits.
from users. In the future, freight traffic is            In the aviation arena, the Federal Aviation
projected to grow substantially, putting strain          Administration (FAA) is leading a multi-
on our nation’s transportation systems, but              agency effort to transform the air traffic control
current planning and financing mechanisms                system in order to safely handle the projected
impede public strategies to address needs, and           growth in the demand for air travel. While
industry’s ability to fund its capacity increases        these steps are encouraging, successfully
to meet growth is largely uncertain.                     addressing the nation’s mobility needs requires
        The      challenges      in    reforming         strategic and intermodal approaches and
transportation finance systems are critical to           solutions.
maintaining and improving our nation’s                            Improving transportation safety is an
mobility. The nation’s infrastructure is under           imperative. Each year over 44,000 people are
great strain; congestion across modes is                 killed and over 2.5 million are injured in


                                                    27
transportation-related accidents. Of particular        made significant progress in its handling of air
concern is the limited progress in improving           traffic control acquisitions, but a key challenge
safety on our nation’s roads, where about 95           going forward will be to institutionalize these
percent of all transportation fatalities occur.        improvements and to continuously improve in
Projected increases in congestion across modes,        this area. FAA and JPDO also need to provide
as a result of population and economic growth,         Congress with a valid and comprehensive
could cause deterioration in transportation            estimate of the costs of the NextGen system,
safety despite vigorous efforts to reduce              including the identification and costs of
accidents. To address these problems, the              necessary      research,     development,     and
department is carrying out a number of                 demonstration       projects.      One    limited,
initiatives related to improving aviation,             preliminary estimate concluded that FAA’s
commercial motor carrier, highway, railroad,           budget under a NextGen scenario would
and pipeline safety. However, certain areas            average about $15 billion per year through
require increased attention. In particular,            2025, or about $1 billion more annually (in
improvements in data, performance measures,            today’s dollars) on average than FAA’s fiscal
and evaluations are needed to determine                year 2006 appropriation. JPDO has estimated
whether programs are achieving intended                that failure to achieve a timely transition to
results. For example, agencies need to develop         NextGen could result in a gap between the
better measures of the direct results of their         demand for air transportation services and
efforts—such as safety improvements made as            available capacity that could cost the U.S.
a result of enforcement of safety standards—           economy billions of dollars annually.
that contribute toward reductions in accidents.                 In addition, the department and the
This information can also hold agencies                transportation sector as a whole face persistent
accountable for the performance of their               human capital challenges that put their mission
programs and support congressional oversight.          performance at risk. Both face an impending
         FAA has worked with the Joint                 shortage of people with the skills and
Planning and Development Office (JPDO) to              competencies they will need in the future.
design and plan the Next Generation Air                Furthermore, while the department has made
Transportation System (NextGen) and will face          significant improvements in recent years in its
challenges as it moves toward implementation           financial management, it received a qualified
and integration of NextGen systems. This               opinion on its 2006 financial statements
transition from the current air traffic control        because of material weaknesses related to
system to the broader and modernized NextGen           certain FAA activities. Finally, the department
system will be one of the Department of                has retained some responsibilities and
Transportation’s most complex undertakings.            involvement in transportation security and
In previous years, FAA has faced systemic              emergency preparedness and response and is
management and acquisition problems that led           working with the Department of Homeland
us to designate its air traffic control                Security to further clarify its role.
modernization program as high risk. FAA has




                                                  28
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                     e-mail jsemmens@cox.net

                                           MARCH 2007

Statewide Travel Forecasting Models, NCHRP Synthesis 358 by Alan Horowitz, Center for Urban
Transportation Studies, University of Wisconsin-Milwaukee (Transportation Research Board, 500
Fifth Street, NW, Washington, DC 20001; (202) 334-3213; http://gulliver.trb.org/bookstore) (2006)


Highlights                                                      The state of the practice has matured
 Statewide models have proven to be                    over the last 10 years. Many statewide travel
  versatile tools in statewide planning.                forecasting models now have network detail
 Most states do not expect their models to             similar to urban models. Validation standards
  validate as well as urban models.                     have increased, such that some models are now
                                                        able to achieve the same level of accuracy as
        Statewide travel forecasting models             urban models. With the exceptions of Ohio and
attempt to meet some of the same goals for              Oregon, statewide models still closely follow
statewide transportation planning that urban            urban models in structure within their
travel forecasting models have met for urban            passenger travel components. However, there is
transportation planning. In the past 10 years           a trend away from truck-only freight
statewide transportation planners have seen             components toward commodity-based freight
dramatic improvements in socioeconomic and              components, which better exploit available
network databases, tools for accessing these            freight databases. Ohio and Oregon are
databases,     and     computational     power.         implementing a new modeling paradigm that
Consequently, interest in fully capable                 integrates forecasts of economic activity and
statewide travel forecasting models has steadily        land use into the travel model.
increased. Approximately one-half of the states                 Statewide models have proven to be
now have functional models.                             versatile tools in assisting in the development
        Information about modeling activities           of both statewide and metropolitan area plans.
was provided by 49 states returning at least one        Such models are primarily used for intercity
questionnaire. The responses to the synthesis           corridor planning, statewide system planning,
questionnaires, along with those from an earlier        and bypass studies; however, they are also
questionnaire distributed by the TRB Statewide          frequently used for providing input to
Travel Demand Models Peer Exchange in                   metropolitan planning organization (MPO)
2004, allow for a general assessment of the             models, replacing MPO models, or serving as
state of the practice. The questionnaires               the main forecasting means for rural projects.
focused on individual components of the                 Statewide models have been used in several
models and the modeling process. To achieve a           states for air quality conformity analysis,
better understanding of how all the pieces fit          freight planning, traffic impact studies,
together, five case studies are presented to            economic development studies, project
provide a broader overview. In addition,                prioritization, and many other planning needs.
several states were asked to expand on their                    Given that there are no best-practice
questionnaire responses with regard to how              standards for statewide models, different states
statewide models have been successfully                 have taken different approaches to building
applied.                                                their models to meet their particular needs.


                                                   29
Development times range from approximately               commodities, and then using the commodity
6 months to 8 years, and development costs               flow forecast to estimate vehicle flows. Three-
have ranged from less than $100,000 to many              fourths of states reporting freight components
millions of dollars. The level of detail in both         base their forecasts on commodities. Some
networks and zone systems also varies greatly.           states have explored innovative methods, such
Models fall into five general categories: (1)            as estimating OD tables from traffic counts to
origin-destination (OD) table estimation and             fill in gaps in secondary data sources.
assignment, (2) freight only, (3) passenger                       Statewide models are not yet fully
only, (4) combined passenger and freight, and            integrated with urban models within the state.
(5) integrated passenger/freight/economic                Approximately half of the statewide models are
activity.                                                capable of providing independent estimates of
         Most states with models have avoided            traffic within urban areas; however, statewide
original data collection; tending to rely heavily        models invariably yield to urban models if
on secondary data sources. Important data                there is a disagreement. Also, about half of the
sources for passenger components include the             statewide models are capable of developing
Census Transportation Planning Package, the              external station forecasts for urban models.
National Household Travel Survey, MPO                    Many statewide models base their zone systems
databases, the American Travel Survey, and in-           and network on urban models, although
house traffic counts. Some states have                   simplifications are often necessary.
purchased National Household Travel Survey                        Validation of statewide models exploits
add-ons. Freight data often came from the                many of the same techniques and data sources
Vehicle Inventory and Use Survey, a particular           as urban models. However, most states do not
freight data vendor, the Commodity Flow                  expect their models to validate as well as urban
Survey, and the Rail Carload Waybill Sample.             models. Prominent validation data sources are
         The geographic size of states means that        passenger vehicle counts, truck counts, national
many statewide models are still spatially and            default trip generation values, OD flows from
temporally coarser than urban models. The                the Census Transportation Planning Package,
coarseness is exacerbated by the need to                 and locally collected survey data.
consider long distance trips that start or end in                 The five case studies help to illustrate
other states. Indiana, Ohio, and Texas have the          the wide range of reasonable approaches to
largest zone systems, with more than 4,500               statewide travel forecasting. The cases studies
zones each. Most models have avoided the use             concentrate on the more promising approaches
of special generators. Networks with more than           and indicate how even modest expenditures of
200,000 links have been created. Although                resources can result in powerful tools for
smaller states are capable of running peak-              statewide transportation planning. The Ohio
period traffic assignments, most states run 24-h         case study, in particular, shows what might be
traffic assignments.                                     accomplished when budgets and time permit a
         There are two fundamentally different           full treatment of the interaction between
styles of freight forecasting: (1) direct                transportation supply, transportation demand,
forecasting of vehicle flows without reference           land use, and economic activity.
to commodities and (2) forecasting of




                                                    30
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                     e-mail jsemmens@cox.net

                                           MARCH 2007

Traffic Data Collection Methodologies by Jim French and Millie French, French Engineering,
LLC, 114 Cooler Estate Rd., Smithfield. PA 15478 (Pennsylvania Department of Transportation,
Bureau of Planning and Research, Commonwealth Keystone Building, 400 North Street. 6th Floor,
Harrisburg. PA 17120) (Apr 2006)


Highlights                                                      The test was conducted over the course
 There appears to be good potential for using          of two days, September 14 and 15, 2005. The
  portable non-intrusive traffic data collection        equipment was set up at each site by vendor
  equipment.                                            representatives.      Vendors     were    given
 Acoustic sensors might be most appropriate            approximately two hours to set up, and data
  in areas where an overhead sensor is needed.          collection at each site was four hours in
 Microwave sensors might be most                       duration.
  appropriate in areas where it is desired to                   Compared to the Minnesota Guidestar
  move the sensor as far as possible from the           research, the microwave sensors performed
  traveling lanes.                                      about the same in the freeway environments,
 Infrared might be most appropriate in                 while the acoustic sensor matched the manual
  instances where truck classification is               counts at the Pennsylvania freeway sites at a
  important.                                            higher rate than it did in Minnesota.
                                                                In the non-freeway environments, the
        The purpose of this research was to             Smart Sensor performed about the same as it
field-test portable and permanently-installed           did in the Pennsylvania and Minnesota freeway
non-intrusive traffic data collection equipment.        environments, while the RTMS and SAS-1 did
        As specified by the Department, the             not match the manual counts as closely in non-
four non-intrusive traffic counters tested were         freeway environments.
as follows:                                                     The results for the TIRTL matched the
    o RTMS by EIS (Microwave)                           Minnesota research relatively closely when
    o SAS-l by Smartek (Acoustic)                       spanning two-lanes, however, its rate of
    o Smart Sensor by Wavetronix                        matching the manual counts in the four and
        (Microwave)                                     five-lane test sections was much lower than the
    o TIRTL by Control Specialists (Infrared)           Minnesota research.

Field Testing of Equipment in a Portable Setup          Field Testing in a Permanent Setup
        Four sites were selected in the                         For     testing   the     non-intrusive
Uniontown, Pennsylvania area. The primary               technologies in a permanent setup, six Mobility
objective of the site selection was to provide a        Technologies (traffic.com) sites in the
cross-section of roadside environments for              Pittsburgh and Philadelphia area were selected
equipment setup. A secondary objective was to           for a quality assurance check. The sample was
select sites near in-pavement traffic counting          comprised of two microwave (RTMS X2)
stations operated by PennDOT.                           sensors each in the Philadelphia and Pittsburgh
                                                        areas, and two acoustic (SAS-1) sensors in the


                                                   31
Philadelphia area. At each site, three hours of           short term counts and the microwave sensor in
traffic volume and classification data were               matching the manual counts.
manually collected for comparison to the                          There was no statistically significant
sensor data. At the microwave sensor sites, the           difference between the best performing
classification scheme was simply to                       acoustic sensor and best performing microwave
differentiate between trucks and passenger                sensor. Similarly, there was no statistically
vehicles. At the acoustic sensor sites, the               significant difference between volumes
classification scheme was to differentiate                collected by microwave sensors from the near
between passenger vehicles, single-unit trucks,           and far side lanes. This may be an indication
and tractor-trailer trucks.                               that there was no difference in reality.
         Both the microwave and acoustic
sensors demonstrated the ability to provide               Conclusion
accurate traffic volume counts. The acoustic                      In short, there appears to be good
sensor performed very well at the S.R. 0476               potential for using portable non-intrusive traffic
site near Chemical Road, having differed from             data collection equipment in Pennsylvania.
the manual counts by less than 1% on the three-           PennDOT should make use of all three
hour volume, and reporting a vehicle                      technologies since each has circumstances in
composition that matched the manual counts                which it is likely to perform the best. Acoustic
very closely. The microwave sensors at S.R.               sensors might be most appropriate in areas
0376, S.R. 0422 and S.R. 0202 demonstrated                where an overhead sensor is needed, but the
conformance with the manual counts to within              right-of-way is limited and overhead utilities
5%, although the under-classifying of trucks              are not an issue. Microwave sensors might be
was prevalent throughout all of the microwave             most appropriate in areas where the right-of-
sites. Of the six sites, four provided good               way is not an issue and it is desired to move the
counts. The S.R. 0279 site was rejected as an             sensor as far as possible from the traveling
outlier because the sensor was not set up to              lanes. The TIRTL might be most appropriate in
monitor all of the lanes. The S.R. 0476 site near         instances where truck classification is
S.R. 0076 was rejected because of an extreme              important and roadway geometry allows the
unexplained disparity between the manual                  device to be set up to manufacturer's
counts and the sensor counts.                             specifications.       Both       trailer-mounting
         At the S.R. 0422 Eastbound site, the             telescoping poles and temporary poles have the
microwave sensor matched the manual counts                potential for use in Pennsylvania, however, the
closer than the PennDOT short term counts by              persons responsible for the devices should
a margin of 2.2%. This was sufficient to detect           exercise engineering judgment to ensure that
a statistically significant difference between the        the safety of the motoring public or capacity of
                                                          the roadway is not jeopardized.




                                                     32
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Median Barrier Guidelines for Texas by Roger Bligh, Shaw-Pin Miaou, Dominique Lord, and
Scott Cooner, Texas Transportation Institute, Texas A&M University System, College Station,
Texas 77843-3135 (Texas Department of Transportation, Research and Technology Implementation
Office P.O. Box 5080, Austin, Texas 78763-5080; 979.845.1734; http://tti.tamu.edu) (Aug 2006)


Highlights                                                vehicle,       roadway,      and      operational
 If the mean CMC rate exceeds 0.4/mile/year,             characteristics may necessitate changes.
  a median barrier should be considered.                          Under this project, new guidelines were
 High-tension cable barriers are generally               developed to assist highway engineers with the
  more cost-effective than concrete barriers              evaluation of median barrier need such that the
  for the range of median widths > 20 ft.                 highest practical level of median safety can be
                                                          achieved. The recommended guidelines are
        When they occur, cross-median crashes             based on analysis of median-related crashes in
are typically very violent in nature and have a           Texas. The crash data were used to develop
high probability of multiple serious injuries and         crash statistical models for the various types of
deaths. Research shows that cross-median                  median-related crashes. Based on the estimates
crashes are responsible for a disproportionately          derived from the frequency and severity models
high rate of fatalities in Texas and other states.        and crash costs used by the Texas Department
Many of these severe cross-median crashes can             of Transportation, an economic analysis of
be prevented with adequate barrier protection.            median barrier need was performed.
However, barriers should not be used                      Benefit/cost (B/C) ratios for installing median
indiscriminately as they, too, constitute a               barriers were computed for various average
hazard to motorists. A barrier is typically               annual daily traffic and median-width
warranted when the consequences of                        combinations. In general, it was found that the
encroaching into or across the median is judged           mean B/C ratio increases as average annual
to be more severe than striking the barrier.              daily traffic (AADT) increases and decreases as
        TxDOT's Roadway Design Manual                     the median width increases.
differentiates guidance for median barriers on                    The results of the benefit/cost analysis
the basis of control of access and median width.          were used to formulate median barrier
Median barriers are generally provided for                guidelines for divided freeways as a function of
controlled access highways with medians of 30             median width and AADT. Based on the median
ft or less in width. If justified through an              width and actual or expected AADT for an
operational analysis, median barriers may be              existing or new facility, respectively, the need
provided for medians with widths greater than             for a median barrier can be assessed.
30 ft. However, while the guidelines mention              Additionally, mean cross-median crash rates
operational analysis, there is no guidance given          were computed for each of the priority zones
on specific cross-median crash rates that might           established by the guideline. The cross-median
justify the use of a median barrier on an                 crash (CMC) rates are useful to highway
existing freeway. Furthermore, the current                engineers in making decisions regarding
guidance is based on aging data, and changes to           median barrier needs on existing highway


                                                     33
sections based on a highway section's mean                          High-tension cable barrier systems are
cross-median crash history computed over a                 rapidly gaining popularity in median
five-year period. Generally speaking, if the               applications. These weak-post systems are
mean CMC rate exceeds 0.4 CMC per mile per                 typically less expensive to install than strong-
year, a median barrier should be considered.               post or rigid concrete barriers. Their flexible
        Until the recent acceptance of high-               nature imparts lower decelerations to impacting
tension cable barriers, TxDOT relied almost                vehicles and their occupants, resulting in a
exclusively on concrete barriers for separating            lower impact severity and probability of injury.
opposing lanes of traffic. Concrete barriers are           The high tension reduces dynamic deflection
well suited for use in narrow medians along                and enables the cables to remain elevated after
high-speed, high-volume roadways due to their              an impact. Thus, the barrier often retains much
negligible deflection, low life-cycle cost, and            of its functionality and can accommodate
relatively maintenance-free characteristics.               additional impacts between the time the barrier
However, rigid barriers impose greater                     is impacted and its subsequent repair.
decelerations on impacting vehicles than more              Socketing the support posts in concrete
flexible systems and, depending on the barrier             footings increases installation cost but
profile and impact conditions, can impart                  facilitates rapid repair of the cable barrier after
instability to a vehicle as well.                          an impact, thereby reducing the cost and time
        In addition, due to the contact with               of repairs and exposure of workers.
numerous posts, cable barriers often "capture" a                    Analyses conducted under this project
vehicle (i.e., bring it to a safe stop) rather than        indicate that high-tension cable barriers are
redirect it back onto the roadway where a                  generally more cost-effective than concrete
secondary crash can result. A disadvantage of              barriers for the range of median widths for
weak-post systems is the additional space                  which they are applicable (i.e., > 20 ft).
required to accommodate the larger design
deflections.




                                                      34
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Development and Implementation of Highway Structures Information System for Wisconsin
Department of Transportation by Scot M. Becker, W. Travis McDaniel, and Eric Baeverstad in
Transportation Research Record 1958 (Transportation Research Board, 500 Fifth Street, NW,
Washington, DC 20001; (202) 334-3213; http://gulliver.trb.org/bookstore) (2006)


Highlights                                               lights, etc.). That, combined with dwindling
 The HSI system allows all stakeholders to              resources, made maintaining several different
  have a one-stop shop for structure                     files for one bridge complicated and inefficient.
  information, modeling, analysis, &                              By the mid-1990s, Wisconsin DOT
  management.                                            visualized a business model that would create a
 HSI has received accolades for its quick and           centralized data repository for all information
  efficient response time, ease of use, and              about a structure. This vision included
  accuracy of data.                                      identifying all stakeholders and data users, as
 HSI has provided a systematic approach to              well as allowing access to this information in a
  achieving asset management of structures in            quick and user-friendly application. It was also
  Wisconsin.                                             important to allow experts from throughout the
                                                         state to access and maintain their particular
        The philosophy on highway structure              component of the information.
asset management has evolved over the past                        It was also envisioned that a system
two decades at the Wisconsin Department of               would need to be developed to manage all
Transportation's (DOT) Bureau of Structures              types of structures important to Wisconsin
and required a new system approach to data               DOT. As development of this system
management and modeling. Before 2000,                    continued, a notion of a structural data life
Wisconsin DOT kept only bridge structure                 cycle and subsequent grouping of the data
data. To maintain these data, the agency used a          became apparent to stakeholders.
DB2 (mainframe) database for inventory                            The Highway Structures Information
information and an Oracle-based client server            (HIS) system is a systematic approach to
(PONTIS) for inspection information. In                  effectively managing all state and locally
addition,      engineers     used     stand-alone        maintained structures through a responsive,
applications with .txt file data for design and          efficient system. When state and local program
rating applications and also maintained a                managers are equipped with real-time
complex bridge log for oversized and                     performance data and up-to-date file
overweight vehicle routing performed by the              information, they can make better-informed
Department of Motor Vehicles. This situation             decisions on resource allocation and can
resulted in many disconnected areas of                   continually fine-tune operations on a monthly
information. There was an increase in                    basis. Now, all bridge inspectors can input
information requests over the years and an               online their current inspection reports. This
increase in calls for maintenance of additional          situation stands in stark contrast to the previous
data on ancillary structures (sign bridges,              process that was either manually administered
culverts, retaining walls, noise walls, high-mast        or juggled between two separate databases.


                                                    35
Program managers have the opportunity to                efficient response time, ease of use, and
manage their own resources and monitor                  accuracy of data. Major improvements in data
performance of their bridges.                           collection are now provided through many
        In addition, HSI is a valuable resource         more editing checks on new data input. Also, it
to contractors, consultants, and DOT                    is now much easier to cleanse the data by
management teams to search for a wide range             writing edit programs that search for obvious
of data and indicators of current and historical        errors.
performance in response to inquiries from                       A major improvement from this system
legislators, public citizens, and media. A large        is efficient management of infrastructure
menu system provides~ easy method for users             structure assets by the local bridge managers,
to inquire about specific data and create their         rather than their reliance on archaic methods or
own customized reports. This process provides           advice from a central office. The program has
instantaneous responses to requestors and               provided ownership to people directly
eliminates their waiting in line for bridge             connected with managing their bridges and
personnel to generate answers to queries.               given them a sense of pride in knowing they are
        The system has provided many new                using the latest technology to perform their
benefits to the bureau of structures and the            jobs.
structure program for the State of Wisconsin.                   Success has come quite soon, for now
For the first time, all stakeholders have a one-        the district bridge managers have commented
stop shop for structure information, modeling,          that each of them has several more counties
analysis, and management. This has allowed              entering their own inspections online as
communication across division lines, like the           opposed to their mailing them to the districts to
permitting section in the Division of Motor             enter. In addition, larger cities in the state have
Vehicles and the planning and budgeting                 started to use this tool as a primary program
section in the Division of Transportation               management tool. Contractors, field personnel,
Investment Management. The development                  and people in academia have also praised this
section can produce timely reports for                  tool.
legislatures, planners, contractors, and those                  HSI provides a framework for citizens
engaged in research activities, to name a few.          and legislators to monitor performance, be kept
        Since the initial training programs in          apprised of top initiatives, and have confidence
eight districts for all state and local bridge          in the management of funds allocated for the
managers, central office field trips for program        state's bridges. It offers the opportunity to
management have been virtually nonexistent.             request more funding if results show it is
Central office personnel now concentrate their          needed, through the competent and reliable
efforts on enhancements to the system,                  bridge management system. HSI has provided a
cleansing data, and providing telephone                 systematic approach to achieving asset
responses to inquiries from the field. By having        management of structures in Wisconsin. Never
a consistent interface, users and access points         before has the maintenance side and funding
users can have confidence in the data and               been as integrated to the improvement program
decisions they make in DOT.                             and life cycle of structures as it is today.
        The program has received accolades
from a great many users for its quick and




                                                   36
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Interim Recommendations for the Use of Lithium to Mitigate or Prevent Alkali-Silica Reaction
by Kevin J. Folliard, Michael D.A. Thomas, Benoit Fournier, Kimberly F. Kurtis, and Jason H.
Ideker, The Transtec Group, Inc., 1012 East 38½ Street, Austin, TX 78751 (Office of Infrastructure
Research and Development, Federal Highway Administration, 6300 Georgetown Pike, McLean,
Virginia 22101-2296) (July 2006)


Highlights                                                changes have been made, and the
 LiN03 has been found to be the most                     recommendations provided within the current
  efficient compound in controlling                       document should be considered to be the most
  expansion.                                              relevant and applicable to future applications of
 Combined use of lithium and SCMs                        lithium. The following highlights some of the
  (especially fly ash and slag) is recommended            key modifications and revisions made to the
  to reduce the economic impact of using                  current guideline document:
  lithium.                                                        Deleting         the          prescriptive
 Lithium compounds have proven to be                     recommendations for the use of lithium as an
  effective in post-treating hardened mortar.             admixture in new concrete. The exact
                                                          relationship between the amount of lithium
         Alkali-silica reaction (ASR) is a major          required and the nature of the reactive
durability problem that has resulted in                   aggregate is not clearly understood. Recent
premature deterioration of various types of               studies have shown that dosages higher than
concrete structures in the United States and              100% of the standard dosage may be needed to
throughout the world. Although the potential              suppress expansion for several major aggregate
for lithium compounds to control ASR-induced              types. Consequently, it is not appropriate to
expansion has been known for about 50 years,              specify a single dose for all reactive aggregates
there have been limited field applications with           and the dose required has to be determined by
even      less    comprehensive       performance         testing individual aggregate sources with
monitoring. In the past 10 years, however, there          lithium.
has been renewed interest in using lithium as                     Deleting the modified accelerated
either an admixture in new concrete or as a               mortar bar test (AMBT) in the performance
treatment of existing structures. Because of the          specification. This test underestimates the
limited use of lithium compounds in laboratory            amount of lithium required for the control of
research and field applications, guidelines have          expansion with a number of reactive aggregate
been      lacking.     This     report    presents        types.
recommendations for practitioners to test,                        Updating summary of field studies to
specify, and use lithium compounds in concrete            include recent applications of lithium.
construction and repair applications.                             Updating literature review to include
         This report replaces the previously              recent publications.
published lithium guideline report (Guidelines
for the Use of Lithium to Mitigate or Prevent
Alkali-Silica Reaction (ASR). Substantial


                                                     37
Conclusions                                                LiN03 has been found to be the most efficient
        This report has reviewed the basics of             of the above compounds in controlling
ASR, summarized past research and field                    expansion because, unlike, the other lithium
applications of lithium compounds in concrete              salts, LiN03 does not increase pore solution pH.
construction,      and      presented       revised                A substantial portion of lithium is
recommendations for using lithium in new                   absorbed in early hydration products, thereby
concrete and as a post-treatment for existing              requiring higher dosages of lithium compounds
structures. Some of the main findings and                  to offset this loss and to control expansion
conclusions from this report are:                          adequately. The development of a lithium-
        ASR is a significant problem in the                bearing glass has been reported as a means of
United States and elsewhere, but there are                 minimizing this uptake of lithium by hydration
several methods available for preventing ASR-              products, thereby resulting in more efficient use
induced expansion, including the use of non-               of the active lithium compound in controlling
reactive aggregates, low alkali concrete,                  ASR-induced expansion.
supplementary cementitious materials (SCMs),                       The combined use of lithium and SCMs
and lithium compounds.                                     (especially fly ash and slag) is recommended to
        The mechanisms by which lithium                    reduce the economic impact of using lithium
compounds suppress ASR expansion are not                   and to produce low-permeability concrete that
understood fully, but it is evident that lithium is        is more resistant to ASR and other deterioration
incorporated into ASR gel, rendering the gel               mechanisms.
essentially non-expansive. ASR gels still form                     The test method most recommended for
in the presence of lithium; however, their                 assessing lithium compounds in the laboratory
altered structure (perhaps lithium substituting            is ASTM C 1293, with a test duration of 2
for calcium) inhibits water absorption and                 years. Other more rapid tests are not currently
expansion.                                                 available as an alternative to ASTM C 1293.
        A variety of lithium compounds,                            Lithium compounds have proven to be
including LiCl, Li2C03, LiF, Li2Si03, LiN03,               effective in post-treating hardened mortar or
LiOH-H2O, LiNO2, and Li2S04 have been                      concrete in the laboratory that has already
shown in laboratory studies to inhibit ASR-                expanded from ASR, thereby reducing or
induced expansion effectively, provided that               eliminating future expansion.
they are used at a sufficiently high dosage.




                                                      38
TRANSPORTATION RESEARCH DIGEST
               ARIZONA TRANSPORTATION INSTITUTE
                                        e-mail jsemmens@cox.net

                                              MARCH 2007

A Qualitative Study of the Core Functions of Smart Traffic Centers at the Virginia Department
of Transportation by Gene Tey Shin, Virginia Transportation Research Council, 530 Edgemont
Road, Charlottesville, VA 22903 (Virginia Department of Transportation, 1401 E. Broad Street,
Richmond, VA 23219) (June 2006)


Highlights                                                  management of incidents and emergencies and
 Incident management is the primary core                   to mitigate their impact on regional traffic flow.
  function of the Smart Traffic Center (STC).               However, where the Safety Service Patrol
 The presence of a fully developed Safety                  (SSP) is limited or absent, the STC must also
  Service Patrol (SSP) greatly enhances the                 network to develop good relations with
  functionality of the STC.                                 agencies that do have the resources to respond
                                                            to incidents directly.
       The core function of VDOT'S Smart                             Regional networking strategies often
Traffic Centers (STCs) has expanded beyond                  depend on the personal experiences of
simply disseminating information to the public,             particular VDOT staff. The efforts of these
although that activity still remains a critical tool        STC managers are highly laudable, but such
of both traffic and incident management. STCs               dependence leaves VDOT vulnerable should
have four core functions:                                   these individuals leave the agency.
    1) traffic management                                            The presence of a fully developed SSP
    2) incident management                                  greatly enhances the functionality of the STC.
    3) emergency operations/emergency                       Where the SSP is fully operational, the STC's
       management                                           ability to manage incidents, gather information,
    4) regional networking.                                 and interact directly with the public and other
                                                            state, local, and federal agencies is complete.
         Incident management is the primary                 Where a functional SSP is not present, the
core function of the STC. Incident management               STC's ability to manage incidents directly (and
activities and events define the vast majority of           therefore traffic) is limited, impaired, or
work undertaken at STCs and drive the                       disabled.
development of systems, procedures, policies,                        VDOT's STCs are critical to
and relationships with communities, agencies,               coordinating and working directly with other
and private companies with whom the STC                     local, state, and federal agencies. VDOT is
must work on a daily basis.                                 responsible for maintaining the transportation
         Regional networking is critical to                 infrastructure, and the STCs comprise VDOT's
successful STC operations. This is particularly             most extensive, direct, and continuous two-way
clear in regions where the large number of cites            interaction with the public. Therefore, the STCs
and communities that directly abut multiplies               provide a natural source of information and
the number of responder agencies and                        leadership in coordinating the efforts of diverse
organizations. The inherent complexity of such              agencies with VDOT and each other.
regions necessitates careful coordination and                        Computer systems, procedures, and
networking to ensure the safe and efficient                 practices vary widely across STC locations.


                                                       39
Although it was beyond the scope of this report          reinforce the ties among STCs and maintain
to discuss the variation of systems, procedures,         effective sharing of information and practices
and practices across STCs, this variation was a          across locations.
major challenge to data collection and presents                  SSPs should be fully developed at each
significant issues for standardization of                VDOT STC. The SSP is arguably the single
performance measures and processes. Roles                most practical and powerful resource an STC
and titles vary from location to location, as do         can have in managing incidents and developing
organizational structures and responsibilities.          strong relations with the public, local
Until this variation is minimized, the                   communities, and other agencies. In addition to
development of standardized performance                  serving as the STC's most reliable and versatile
measures and processes will remain                       information resource, the SSP's physical
problematic.                                             presence on the road raises the STC's
        The STC operations managers benefited            functionality from disseminating information to
from the establishment of the Community of               managing incidents and traffic directly.
Practice. The meetings held to discuss core                      Each STC should institutionalize its
functions comprised the first opportunity for            regional traffic operations network. Currently,
STC personnel to communicate consistently                regional traffic operations networks are greatly
with their counterparts or to visit each STC             enhanced by or depend on the personal
location in person. Prior to these meetings, each        experiences and efforts of individual STC
STC was developing solutions to similar                  personnel. If these individuals were to vacate
problems entirely independently, such as how             their positions, the STCs would need to
to forge a close relationship with the VSP.              reconstruct these networks. Since close
Discussions of core functions routinely yielded          working relationships with all regional
practical examples of best practices, lessons            responder agencies are critical to effective
learned, and ideas for developing both                   incident management, regional networking
individual STCs and improved traffic                     plans and procedures should be documented
operations across the state.                             and formalized at each STC to the greatest
                                                         practical extent.
Recommendations                                                  STC operations managers should share
        STC operations managers should                   regional networking experiences and processes,
continue to meet and share lessons learned and           because close working relationships with all
best practices in order to coordinate the                regional responder agencies are critical to
development of practices and procedures.                 effective incident management. Regional
Although there will always be some variation             networking plans and procedures should be
because of regional needs, coordinating and              carefully developed at each STC to the greatest
regulating practices and processes will lay the          extent possible. Sharing experiences and
groundwork for standardized performance                  processes across locations will support and
measures. Regular, face-to-face meetings will            enhance that development.




                                                    40
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

Bus Use of Shoulders, TCRP Synthesis 64 by Peter Martin, Wilbur Smith Associates, San
Francisco, California (Transportation Research Board, 500 Fifth Street, NW, Washington, DC
20001; (202) 334-3213; http://gulliver.trb.org/bookstore) (2006)


Highlights                                                and traffic impacts result. The shoulder bus
 Bus use of highway shoulders to bypass                  operations also facilitate the development of
  congestion represents a low-cost and                    rail transit-like "station stopping" service,
  relatively quick strategy to improve bus                because buses can easily enter and exit the
  running times and reliability.                          highway. This station stopping service can only
 With proper operating rules and upgrades to             be accomplished at great expense for bus
  shoulder facilities the bus use of shoulders            services that use median high-occupancy
  to bypass congestion has been a success.                vehicle (HOV) lanes, because buses on these
                                                          median facilities generally must maneuver
         In many urban areas, traffic congestion          across general traffic to get to and from the
commonly delays bus services and adversely                HOV lanes and the highway on- and off-ramps.
affects schedule reliability. Some communities            The solution to the weaving problem is to
have adopted policies and regulations that                construct expensive HOV direct access ramps.
permit buses to use shoulders on arterial roads                   Both the transit and highway
or freeways to bypass congestion either as                perspectives on the bus use of shoulders are
interim or long-term treatments. Delaware,                explored, recognizing that they must be
Georgia, Maryland, Minnesota, New Jersey,                 partners in expanding promising applications
Washington, Virginia, British Columbia, and               for increasing patronage and improving
Ontario are among the jurisdictions that have             operating efficiency. In this report, BBS stands
implemented or are considering implementing               for bus bypass shoulder operations. This
bus use of shoulder programs. Many                        acronym is used by other countries to describe
jurisdictions, however, have been reluctant to            their bus shoulder congestion bypass
embrace bus use of shoulders for various                  operations.
reasons. Little information has been available                    BBS operations have proven popular
about the affects on travel time, reliability,            with bus passengers who benefit from the
patronage benefits, and safety resulting from             improved schedule reliability and quicker travel
the allowed use of shoulders.                             times. Such operations also have improved bus
         In parts of the United States, bus use of        operating efficiencies and have not drawn
highway shoulders to bypass congestion has                significant complaints from general traffic
been in operation for more than 10 years. It              motorists. Positive passenger perception of
represents a low-cost and relatively quick                travel time savings helps to attract patronage.
strategy to improve bus running times and                 Passengers enjoy the feeling of moving faster
reliability without requiring costly expansion of         than the general traffic. For bus operators, BBS
the highway right-of-way. Because the bus                 operations allow them to offer more reliable
shoulder operations can be implemented within             service, which is particularly important for
the highway right-of-way, minimal disruption              buses that make more than one peak direction


                                                     41
commute period trip; the second peak direction             o Return merge distance adequacy;
bus trip is more likely to be on time. Other               o Shoulder area debris hazards;
attractive aspects of BBS applications are that            o Reduced clearance for buses at bridge
they can be implemented relatively quickly and               abutments; and
are very cost-effective owing to their low cost.           o Highway drainage.
BBS projects typically do not require new
rights-of-way and visually they are much less                  Although a number of agencies have
obtrusive than other capacity enhancements              been constructing shoulders to full traffic lane
such as widened highways and direct-ramp                standards, implementing BBS operations on
interchange. In addition, BBS operations lend           older freeways often necessitates upgrades to
themselves to station stopping express bus              shoulders. Many highway shoulders are 10 ft
service on freeways, because entering and               wide or less and are not constructed to support
exiting the freeway involve minimal traffic             high volumes of bus traffic. Buses themselves
conflicts.                                              are nearly 10 ft wide, including mirrors, and are
        From a highway operations and safety            very heavy vehicles. Drainage side slopes and
viewpoint the BBS use operations raise a                catch basins sometimes also need modification
number of important concerns. These concerns            to provide comfortable bus rides. Signage and
encompass the loss of basic functions that              pavement markings also must be provided for
shoulders are intended to provide (removal and          safe operations. The extent of these
storage of disabled vehicles, emergency vehicle         modifications varies by jurisdiction and by
access, and highway maintenance staging),               highway.
traffic safety risks, and the added costs for                  What appears clear is that with proper
maintenance and enforcement. The traffic                operating rules and prudent upgrades to
safety concerns include:                                shoulder facilities the bus use of shoulders to
                                                        bypass congestion has been a success.
   o Conflicts at on- and off-ramps;
                                                        Successful concepts are copied and the bus
   o Sight distance adequacy, particularly at
                                                        shoulder congestion bypass concept has been
     on-ramps;
                                                        copied and currently appears to be expanding
   o Conflicts for motorists pulling onto the
                                                        into new communities. Its current use in most
     shoulder;
                                                        communities, however, is limited to a few
   o Loss of safe evasive movement shelter
                                                        corridors with significant bus operations,
     area;
                                                        congested traffic conditions, and limited
   o Need for bus driver training;
                                                        opportunities to widen the highway.
   o Speed differential;
   o Impact on adjacent lane motorists;




                                                   42
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                     e-mail jsemmens@cox.net

                                           MARCH 2007

Does it Deliver? Examining Whether Rail Transit Spurs Economic Development in Privatization
Watch by Ted Balaker (Reason Foundation, 3415 S. Sepulveda Blvd., Suite 400, Los Angeles, CA
90034; 310/391-2245; http://www.reason.org/pwvol30no5.pdf) (Vol. 30, No. 5 2007)


Highlights                                              advanced degrees in economics or those who
 Rail investments generally have been                  have taught economics at the college level)
  ineffective and expensive, and the benefits           think building rail transit is a good idea (see
  do not justify the costs.                             “Do Economists Reach a Conclusion on Rail
                                                        Transit?”         available       online       at
         In anticipation of the Phoenix area’s          econjournalwatch.org). Most conclude that rail
first light rail line a recent Arizona Republic         transit usually does not make good on its core
opinion piece considered some of the most               promises, such as reducing traffic congestion,
popular justifications for rail transit. After          improving the environment, and helping the
deciding that rail makes good on some                   transit-dependent poor. But what about
promises, but not others, the author concluded          economic development?
that, on balance, building rail was a good idea.                Making conclusions can be tricky. On
The primary reason wasn’t that it would reduce          the one hand properties close to rail stations
traffic congestion, improve mobility, or help           may benefit from greater accessibility. On the
the transit-dependent poor. The verdict was             other hand, stations come with assorted
based mainly on the belief that light rail would        nuisances (noise, traffic congestion, safety
spur economic development and the author                concerns) that may depress property values.
pointed to a single example (Dallas) where rail                 In Dallas, the positive effect held only
was associated with higher property values.             for areas within one quarter-mile of rail
         Many communities around the nation             stations. While investigating rail transit in St.
come to favor rail transit, in part at least,           Louis, a St. Louis Federal Reserve economist
because they expect it to energize the economy.         discovered both an “accessibility” effect and a
But will it and to whom should we turn to help          “nuisance” effect, but, on balance, the “positive
us make up our minds?                                   accessibility effect outweighs the negative
         Perhaps we should consider what                nuisance effect; so, the net effect of MetroLink
economists have to say. After all, they are             on property values is generally positive.”
trained in benefit/cost analysis and that should        Economists from Cal State Fullerton report that
be at the core of the debate: Will benefits             light rail enhanced residential property values 2
outweigh costs? Indeed the author of the                to 18% in Portland, Sacramento, San Diego,
Arizona Republic article cited a study by two           and Santa Clara. Rail seemed to help property
economists to make the case for rail. But does          values more than it hurt them. Can we assume
that study agree with what other economists             that rail tends to make cities more prosperous?
have found and what do these experts say about          Not exactly.
other justifications for rail?                                  In their analysis of 16 cities over a 30-
         A literature review was conducted to           year time span, economists from Brown
figure out whether economists (those with               University and Tufts reveal that household


                                                   43
income in new rail transit-accessible areas was            surprising…to find the empirical support for
below that of other areas. And, except for                 these     transportation     benefits   to    be
Atlanta and Miami, the income gap widened                  inconclusive.”
after new rail lines opened. The authors suggest                   Measuring rail’s economic impact can
that this supports the view that public transit is         be especially difficult because researchers must
a “poverty magnet.”                                        control for many factors, from market forces to
        Rail systems also tend to drain more               public policies on issues as varied as crime
from a local economy than they contribute,                 rates, regulatory climate, and the quality of
according to an analysis conducted by                      public schools. Before pondering rail transit,
economists from the Brookings Institution and              one economist urges policymakers to consider
U.C. Berkeley. The researchers did not come to             a different question: “Why is economic
this conclusion by simply noting that all                  development not occurring in a given area in
systems operate in the red; instead they also              the first place? Possible reasons include
accounted for larger societal benefits that                relatively high cost to business startups,
transit officials frequently tout. Except for San          unattractive      locations     (crime,     poor
Francisco’s BART, every rail system drained                infrastructure) and unnecessary zoning and
more from the economy than it contributed. In              regulations.”
most cases the yearly drain was in the                             The public debate often strays from
neighborhood of hundreds of millions of                    some simple considerations. It is not enough to
dollars—for example, $171 million in St.                   show that rail (or any other public policy)
Louis, $221 million in Portland, and $457                  provides benefits. Benefits must outweigh
million in Dallas.                                         costs. Rail projects cost hundreds of millions—
        What          about        transit-oriented        even billions—of dollars. One would expect
development (TOD)? It’s hard to find a long-               this level of spending to generate some
range transportation plan anywhere that isn’t              benefits. There are many ways to pursue
peppered with optimistic references to TOD.                economic development, but modest benefits
The idea is to encourage economic                          don’t justify steep costs.
development, alter travel patterns, and reduce                     And if it is to be viewed as the best
congestion, often by building high-density,                choice, policymakers must be able to determine
mixed used developments that encourage                     that it is more effective than other options at
walking and transit use and discourage driving.            achieving a particular goal.
Metropolitan planning organizations typically                      Finally, of those economists who offer a
refer to TOD as if the case were closed, as if             bottom-line, big picture assessment of rail
this kind of planning delivers the results it              transit, the vast majority agree that benefits
promises. Yet, after sifting through the                   simply don’t outweigh costs. Even a relatively
academic evidence a U.C. Irvine-UCLA                       rail friendly economist acknowledges the
research team discovered that “there is little             widespread skepticism in his field: “The
credible knowledge about how urban form                    dominant view of economists has been that rail
influences travel patterns. Given the enormous             investments generally have been ineffective
support for using land use and urban design to             and expensive, and the benefits do not justify
address traffic problems, it was somewhat                  the costs.”




                                                      44
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                      e-mail jsemmens@cox.net

                                            MARCH 2007

The Train Drain: Brookings Institution on Rail Transit in America in Privatization Watch by
Robert W. Poole, Jr. (Reason Foundation, 3415 S. Sepulveda Blvd., Suite 400, Los Angeles, CA
90034; 310/391-2245; http://www.reason.org/pwvol30no4.pdf) (Vol. 30, No. 4, Fall 2006)


Highlights                                                rail system’s benefits is greater than its net cost
 The annual value of the benefits to users is            to taxpayers (i.e., the difference between what
  much less than the annual cost to taxpayers.            the rail system’s customers pay as fares and the
 When non-user benefits are added, only San              total cost to build, operate, and maintain the rail
  Francisco’s BART produces net benefits.                 system).
 All other rail transit systems are net losers.                   On average, rail transit systems cover
 Each of the urban areas with rail transit is            about 40% of their operating costs from
  made poorer by many millions of dollars                 farebox revenues and none of their capital
  each year.                                              costs, according to figures in the National
                                                          Transit Database. That means their net taxpayer
        The Brookings Institution is America’s            subsidy is large.
oldest public policy think tank. Based in                          Winston and Maheshri construct an
Washington, DC, it is well-respected and                  elaborate econometric model to estimate the
generally considered to be moderate-liberal in            “consumer surplus” of 25 rail transit systems.
orientation. As American Enterprise Institute is          This is economists’ term for the benefits to
informally considered a place for Republican              users, over and above the fares they pay. The
office-holders to reside when out of power, so            large systems (New York, Washington, DC,
Brookings is regarded for Democratic icons.               San Francisco’s BART, etc.) all produce
        One of Brookings Institution’s leading            significant consumer surpluses. But most of the
transportation policy experts is Clifford                 smaller ones do not.
Winston, a well-respected economist and                            Next, the authors compare the consumer
author of numerous books and papers dealing               surplus of each system with its net taxpayer
with transportation issues. His most recent               cost. On this measure, every single one of the
paper is “On the Social Desirability of Urban             25 systems has negative net benefits—i.e., the
Rail Systems,” co-authored with Vikram                    annual value of the benefits to users is much
Maheshri, an economist at the University of               less than the annual cost to taxpayers.
California at Berkeley. It appears in the Journal         Surprisingly, this is true even for the massive
of Urban Economics and is available online at             New York City rail transit system, which by
www.sciencedirect.com.                                    itself accounts for two-thirds of the nation’s rail
        The purpose of the paper is to estimate           transit passenger miles.
the contribution of U.S. urban rail systems to                     But what about larger benefits to the
social welfare. The authors define the net                metro area? Rail systems are advocated not just
benefit of a rail transit system as the difference        to benefit their riders, but because they are
between its benefits, broadly measured, and its           expected to reduce traffic congestion, reduce
net cost to taxpayers. If this difference is              air pollution, save energy, etc. So the final step
positive, it means that the dollar value of the           in Winston and Maheshri’s analysis was to


                                                     45
estimate the value of these “externality”                 to be socially desirable, because "supporters
benefits. They first conclude that the only one           have sold [rail systems] as an antidote to the
of these purported benefits large enough to               social costs associated with automobile travel,
make any difference is congestion relief.                 in spite of strong evidence to the contrary."
Adding the congestion savings to road users to            They conclude that, in fact, rail transit is "an
the consumer surplus gives the total benefits of          increasing drain on social welfare."
rail transit. When this total is compared with
the net taxpayer costs, only San Francisco’s                  How Much Rail Transit Drains from Cities Each Year
BART produces net social benefits. Each year                                                             Net Social
                                                          City (agency)
the system improves social welfare by an                                                                   Cost
estimated $36 million. All 23 other U.S. rail             New York (NYC Transit)                        $704 million
transit systems are net losers. This means that           Dallas (DART)                                $457 million
each of those urban areas is made poorer by               Boston (MBTA)                                $453 million
many millions of dollars each year.                       Atlanta (MARTA)                              $302 million
         Winston and Maheshri anticipate that             Denver (RTD)                                 $279 million
some advocates of rail transit will protest that          Philadelphia (SEPTA)                         $271 million
these systems offer other benefits that are not           Washington, DC (METRO)                       $262 million
accounted for in their calculations. For
                                                          San Francisco (Municipal Railway)            $250 million
example,         rail   supposedly      stimulates
                                                          Portland, OR (TriMet)                        $221 million
development around rail stations: “But case
studies have yet to show that after their                 San Jose (Santa Clara Co. Transit)           $211 million
construction transit systems have had a                   Baltimore (MTA Maryland)                     $197 million
significant effect on employment or land use              St. Louis (Bi-State Development Agency)      $171 million
close to stations and that such benefits greatly          Miami-Dade Transit                           $141 million
exceed the benefits from commercial                       Pittsburgh (PA Allegheny Co.)                $135 million
development that would have occurred                      Los Angeles Metro                            $125 million
elsewhere in the absence of rail construction.”           Cleveland (GCRT)                             $118 million
         And there is also the claim that rail
                                                          Sacramento RT                                $106 million
systems increase the mobility of low-income
residents. But the authors point out that the             Northern New Jersey (PATH)                    $87 million
median annual income of rail users in 2001                Newark (NJ Transit)                           $59 million
exceeded $50,000, which was greater than the              Buffalo (Niagara Frontier)                    $57 million
median income of the general population in that           Chicago (CTA)                                 $46 million
year. So rail’s primary market is not the poor            San Diego Trolley                             $29 million
(unlike bus transit).                                     Staten Island (SIRT)                          $21 million
         Overall, then, the authors conclude that         Southern New Jersey (PATCO)                    $7 million
rail transit is erroneously believed by the public




                                                     46
TRANSPORTATION RESEARCH DIGEST
              ARIZONA TRANSPORTATION INSTITUTE
                                       e-mail jsemmens@cox.net

                                             MARCH 2007

The Road More Traveled: Why the Congestion Crisis Matters More Than You Think and What
We Can Do About It by Ted Balaker and Sam Staley (Reason Foundation, 3415 S. Sepulveda
Blvd., Suite 400, Los Angeles, CA 90034; (310) 367-6109; http://www.reason.org/road/) (2006)


Highlights                                                the ideas, technology and capital to eliminate
 Congestion robs the U.S. economy of over                congestion. We just need the willpower."
  $63 billion a year.                                             Through the years our cars and
 Traffic delays are expected to increase by              highways have provided unprecedented door-
  more than 65% over the next 25 years.                   to-door mobility that helped America become
 The book outlines 10 steps that cities and              the most prosperous nation in the world. But
  states can take to reduce traffic significantly.        The Road More Traveled warns that
                                                          bottlenecked roads pose a serious threat to this
         For most of us, traffic has gotten so bad        prosperity. Congestion robs the U.S. economy
that it impacts nearly all of our decisions, big          of over $63 billion a year and traffic delays are
and small. Traffic is a major consideration               expected to increase by more than 65 percent
when we choose where to live, work, shop, and             over the next 25 years. If we don't make up for
even who we'll date or what time of day we'll             years of neglect and prepare for future growth,
leave the house to run errands. Things have               our economy will be crippled by our inability
gotten so bad that the average American spends            to move goods or people.
over 45 hours a year, over a full work week,                      In The Road More Traveled Balaker
stuck in traffic.                                         and Staley detail 10 steps that nearly every city
         Yet, in a disturbing violation of the            and state can take to reduce traffic
"can-do" American spirit, most politicians and            significantly:
planners have simply thrown in the towel and                      1. Add Lanes to Congested Roads and
surrendered to gridlock. "We can't eliminate              Highways: Many say we can’t build our way
traffic and we can't build our way out of                 out of congestion, but we haven’t even tried.
congestion," they lament.                                 Over the last 30 years, vehicle lane miles
         So should we all just accept the daily           traveled have increased by over 143 percent,
grind of traffic as a modern-day fact of life? An         but we’ve added just 5 percent in new capacity.
emphatic "No!" is the answer presented in the             If we removed all of the pork and light rail
new book, The Road More Traveled.                         projects from existing transportation plans and
         "We don't accept failing schools and we          instead built roads and added lanes where they
cannot accept congestion," authors Ted Balaker            are most needed, we could eliminate severe
and Samuel Staley say. "If we're sitting in               congestion for less than we are currently
traffic we aren't playing with our kids or                planning to spend on transportation over the
enjoying our hobbies. Businesses are raising              next few decades.
prices to make up for wasted fuel and lost                        2. Public-Private Partnerships and Toll
productivity. Our time, money, and quality of             Lanes: Cash-strapped governments lack the
life are too valuable to just give up. We have            political resolve to cut spending in nonessential
                                                          programs that would free up money for much-


                                                     47
needed infrastructure projects. Enter the private        freeway speeds by 22 to 89 percent in some
sector. Private companies have recently                  cases.
committed over $25 billion to construct or                       6. One-Way Streets: One-way streets
upgrade toll road projects in six states and             are able to carry 50 percent more traffic and
stand ready to build roads the government can’t          reduce traffic accidents by 10 to 50 percent.
afford to.                                               Yet, many transportation planners haven’t
        3.   Traffic    Signal    Optimization:          taken advantage of this often-simple option.
Surprisingly, many cities have yet to do this,                   7. Incident Management: For each
despite huge potential benefits. Traffic signal          minute that traffic is blocked by an accident,
optimization can reduce stop-and-go traffic by           five minutes of congestion are added to a
40 percent, cut gas consumption by 10 percent,           commute. In most urban areas, much more can
emissions by 22 percent, and travel times by 25          be done to rapidly and effectively manage
percent. A study of 26 such projects in Texas            accidents.
found benefits outweighed costs 38 to 1.                         8. Telecommuting: Telecommuters
        4. Creative Construction: Today’s                outnumber transit commuters in 27 of the
technology offers countless options that                 nation’s 50 largest cities. With communication
weren’t available when our Interstate system             technology constantly improving, companies
was born 50 years ago. For example, Paris is             and governments should encourage more
building a double-decker tunnel deep beneath             workers to skip the commute and work from
historic Versailles to preserve the area and             home.
reduce congestion. And the world’s highest                       9. Parking Reform: Eliminating free
bridge, the Millau Viaduct, a 1 1/2-mile long,           parking and parking subsidies has reduced
800-foot high, $536 million project was built            driving by up to 24 percent in some cities.
using private funding last year.                                 10. Improve Key Intersections and
        5. Freeway Ramp Metering: By                     Access Roads: Overcrowded streets near
controlling the flow of traffic entering                 highways create a negative domino effect that
highways, California has been able to increase           ripples through our entire road system.




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