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					Design Criteria Manual                                                                                Matanuska-Susitna Borough
Chapter 1 - Streets                                                                                    Public Works Department

                                                 TABLE OF CONTENTS

1.0 STREETS.............................................................................................................................1

     1.1        Introduction ..............................................................................................................1

     1.1.1      Planning and Design Documents .............................................................................4

     1.1.2      References ................................................................................................................4

     1.1.3      Codes and Regulations .............................................................................................4

     1.1.4      Permits .....................................................................................................................4

     1.1.5      Design Deviations ....................................................................................................5

     1.1.6      Right of Way (ROW) Development ........................................................................5



     1.2        Functional Classifications ........................................................................................7

     1.2.1      Objectives ................................................................................................................7

     1.2.2      Arterials....................................................................................................................9

     1.2.3      Collectors ............................................................. Error! Bookmark not defined.7

     1.2.4      Local ......................................................................................................................12

     1.2.5      Traffic Volume Determination ..............................................................................14

     1.2.       [Reserved] .......................................................... Error! Bookmark not defined.12

     1.2.       Design Elements ....................................................................................................53

     1.2.       Pedestrian/Vehicle Separations .......................... Error! Bookmark not defined.13



     1.3        Roadway Requirements .........................................................................................17

     1.3.1      Design Criterial .................................................. Error! Bookmark not defined.14

     1.3.2      Roadway Characteristics .................................... Error! Bookmark not defined.14

     1.3.3      Typical Sections ................................................. Error! Bookmark not defined.14

                                                                  Page i
1.3.   Mountain Access ....................................................................................................26

1.3.   Requirements for Paved Streets .............................................................................30

1.3.   Design Criteria .......................................................................................................36

1.3.   General Objectives .................................................................................................36

1.3.   Design and Posted Speed .......................................................................................36

1.3.   Lane........................................................................................................................36

1.3.   Shoulder .................................................................................................................39

1.3.   Horizontal Design Standards .................................................................................39

1.3.   Objectives ..............................................................................................................41

1.3.   Horizontal Curves ..................................................................................................41

1.3.   Visibility Triangles ................................................................................................42

1.3.   Snow Storage .........................................................................................................42

1.3.   Clear Zone ..............................................................................................................43

1.3.   Vertical Design Standards......................................................................................44

1.3.   Objectives ..............................................................................................................44

1.3.   Street Grades ..........................................................................................................45

1.3.   Cross Slopes ...........................................................................................................46

1.3.   Vertical Curves ......................................................................................................47

1.3.   Road Structural Fill Design ...................................................................................70

1.3.   Objectives ..............................................................................................................70

1.3.   Material Specifications ..........................................................................................71

1.3.   Design in Organic Soils .........................................................................................72

1.3.   Road Structural Section Design Methods ..............................................................72

1.3.   Soil Investigation Standards ..................................................................................32

1.3.   Objective ................................................................................................................32
1.3.   Test Holes ..............................................................................................................32



1.4    Optional Design Elements ....................................................................................53

1.4.   Curb and Gutter......................................................................................................__

1.4.   Curb Returns ..........................................................................................................__

1.4.   Curb Cuts ...............................................................................................................__

1.4.   Medians ..................................................................................................................__

1.4.   Guardrails ...............................................................................................................__

1.4.   Retaining Structures ...............................................................................................__

1.4.   Cul-de-sacs, Turn Arounds and Eyebrows ............................................................__

1.4.   Pedestrian Facilities ...............................................................................................__

1.4.   Pedestrian/Vehicle Separations ..............................................................................__

1.4.   Driveways ..................................................................................................................

1.4.   Testing Standards for Usable Material ......................................................................

1.4.   Soils Investigation Report ..........................................................................................

1.4.   Geotextile Fabrics ......................................................................................................

1.4.   Insulation....................................................................................................................

1.4.   Accessibility Requirements .......................................................................................
To Add:

      Dry well,

      low impact development,

      cumulative traffic counts,

      mailbox pullout,

      bus pullout,

      NELB manual,

      Designer definition

      Culvert Marking Posts
      Definitions

      Paving threshold requirement?
FIGURES                                                                                                            Page
Figure 1-1: Typical Right-of-Way Development (NOTE: need to move) .............................53

Figure 1-2: Collector Road Typical Section ...................................................................194, 15

Figure 1-3: Local Road Typical Section .................................................................................17

Figure 1-4: Mountain Access Road Typical Section ..............................................................24

Figure 1-5: Crest Vertical Curve Lengths ...............................................................................50

Figure 1-6: Sag Vertical Curve Lengths .................................................................................51

Figure 1-7: Standard Curb Return Radii .................................................................................56


TABLES


Table 1-1: Average Trip Generation Factors                                                                           10


Table 0-2: Road Characteristics                                                                                      12




Table 0-1: Road Characteristics Bill & Chuck to email me info 5-20 meetingError! Bookmark not defined

Table 0-2: Frost Design Soil Classification ............................................................................73




APPENDICES
Appendix 1A ................................................ Matanuska-Susitna Borough Driveway Standards

Appendix 1B ............................................................ Americans with Disabilities Act Checklist
Design Criteria Manual                                                                                   Matanuska-Susitna Borough
Chapter 1 - Streets                                                                                       Public Works Department

                                                    LIST OF ACRONYMS

AASHTO ......................American Association of State Highway and Transportation Officials

ADA ......................................................................................... Americans with Disabilities Act

ADAAG ........................................... Americans with Disabilities Act Accessibility Guidelines

ADOT&PF ........................ State of Alaska Department of Transportation and Public Facilities

ADT ............................................................................................................ average daily traffic

ASTM ................................................................... American Society for Testing and Materials

L
C..................................................................................................................................... centerline

DCM ...................................................................................................... Design Criteria Manual

GREEN BOOK ............................ A Policy on the Geometric Design of Highways and Streets

ITE ....................................................................................Institute of Transportation Engineers

K................................................................. percent of average daily traffic in peak hour traffic

mph ...................................................................................................................... miles per hour

MSB ............................................................................................... Matanuska-Susitna Borough

MUT1D ....................................... Multilayer User-Friendly Thermal Model in One Dimension

OSHP .................................................................................. Official Streets and Highways Plan

PC................................................................................................................... Point of Curvature

PHT ................................................................................................................... peak hour traffic

PI ................................................................................................................. point of intersection

PT .....................................................................................................................point of tangency

R ......................................................................................................................................... radius

RAP ................................................................................................... recycled asphalt pavement

ROW ..................................................................................................................... Right-of-Way

TBM ......................................................................................................... temporary benchmark


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Design Criteria Manual                                                                         Matanuska-Susitna Borough
Chapter 1 - Streets                                                                             Public Works Department

TIA ........................................................................................................ Traffic Impact Analysis


1.0       STREETS

1.1       Introduction

As areas of the Matanuska-Susitna Borough (MSB) evolve from a rural to urban community,
so does the importance of properly designed streets. In order to meet the present and
projected transportation needs, clear design objectives have been identified to meet specific
goals for safety, functionality, constructability, and durability.

Because of climate, geology, and topography, street design in the MSB can be complex. The
design standards outlined in this manual follow standards established and used nationwide,
with particular emphasis on northern climate design techniques.

The purpose of this manual is to provide traveled ways that are consistent, predictable, safe,
and reliable, through the range of private development, Borough, and State roads. Meeting
this purpose will serve to seamlessly integrate past, present, and future vehicular ways,
pedestrian and bicycle ways, drainage, traffic operations, maintenance, and enforcement.

In addition to achieving uniform design goals, standardized design criteria provide other
benefits. Furnishing clear direction and rationale to the Designer results in economy of scale
and uniformity, reducing costs associated with design, construction, maintenance, and
operations. The Designer is, therefore, able to more effectively approach the design effort in
a manner that is compatible with the needs of the public and in conformance with the various
adopted borough comprehensive plans, the Official Streets and Highways Plan (OSHP), and
other applicable documents. The standards also ensure that safety concerns are addressed
consistently and adequately. Consistency in all areas of the design effort results in a more
cohesive and effective road system within the MSB.

Street design within the MSB encompasses: (1) Borough projects; (2) State projects;
(3) Borough/State projects; and, (4) projects performed by private developers. The codes,
standards, and permits discussed in this section do not apply to state construction projects
within State right-of-way (ROW). However, they do apply to other public and private road

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Design Criteria Manual                                                 Matanuska-Susitna Borough
Chapter 1 - Streets                                                     Public Works Department

designs in the MSB ROW, whether done by the MSB, State or private companies that are
owned or maintained by the MSB. Projects designed and constructed jointly by the MSB and
state will adhere to the design criteria in this manual as well as to appropriate criteria
(mandated by federal laws) contained in state manuals. Consult with the Borough Engineer
for resolution of conflicts among local, state, and federal standards. The Borough Engineer
shall be the final authority in these determinations.




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Design Criteria Manual                                                Matanuska-Susitna Borough
Chapter 1 - Streets                                                    Public Works Department

1.1.1 Planning and Design Documents

1.1.2 References

All reference documents, which are incorporated or incorporated by reference in this Design
Criteria Manual (DCM), shall be the latest edition, unless otherwise noted.

New roads constructed by the MSB shall meet the requirements of this document. MSB may
also be required to meet the following DOT & PF reference standards depending on funding
source requirements:

      Standard Specifications for Highway construction
      Highway Preconstruction Manual
      Standard Drawings

1.1.3 Codes and Regulations

Street design in the MSB is subject to local, state, and federal regulations, standards, and
guidelines. As no single document can ultimately define complete design standards, users of
this manual are cautioned to obtain and carefully read codes and other borough documents
referenced herein to ensure comprehensive design compliance. If conflict appears to exist
among the various codes, borough policies, this manual, or other borough documents The
Borough Engineer shall be the final authority in these determinations.




1.1.4 Permits

Requirements for obtaining permits are mandated by local, state, and federal laws. Permit
conditions can substantially impact the project design. Identification of permits needed and
coordination with each agency must begin early in the design process. Some permit
applications are available by contacting the Engineering Division, from visiting the Public
Works Department at the main Borough office building at 350 East Dahlia in Palmer, or on
the MSB Project Management and Engineer web page. The MSB is not responsible for
determining the necessity for permits or acquiring such permits. When working within the



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Design Criteria Manual                                              Matanuska-Susitna Borough
Chapter 1 - Streets                                                  Public Works Department

incorporated cities, there may be additional permits that apply or supersede MSB permits.
Following is a partial list of permits that may be required.

Floodplain Development Permit. MSB Code Title 17.29 requires that a floodplain
development permit be obtained prior to any development within a flood hazard district.
Flood hazard areas are those within the limit of the boundary of the base 100-year flood, the
highest extreme tide, or a designated special hazard area. Flood maps are on file at the MSB
with the Code Compliance Division. Floodplain development permit applications are
available from the MSB. A Floodplain Development Permit must include both the MSB
Flood Hazard Development Permit and an Elevation Certificate. An Alaska registered
Architect or Engineer must certify the Development Permit Application, and either a
registered Engineer or Surveyor must complete the elevation certificate.

Coastal Management Consistency Determination. The consistency review is typically done in
conjunction with wetlands permits. Projects located within the Coastal Zone shall fill out a
Coastal Project Questionnaire (CPQ). The Planning Department works with the permitting
agency and the State Office of Project Management and Permitting in making local coastal
zone consistency determinations.

General Construction, Encroachment, and Driveway Permits. These permits are required
whenever work is proposed within public easements, encroachments in rights-of-way, and
for construction of a driveway that enters a public right-of-way. The Department of Public
Works requires driveway permit(s) for all existing driveways. If the use of any permitted
driveway changes, the existing permit shall be deemed void and a new permit is required for
the proposed use.

1.1.5 Design Deviations

Designers, whether Borough or private, shall adhere to the criteria established in this DCM
and other referenced documents. A written design deviation request of the appropriate
standard may be requested from the Borough Engineer. Deviation requests must be in
writing and should contain supporting information, justification and suggested solutions. In
addition to the criteria presented in this manual, the Borough Engineer may impose


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Design Criteria Manual                                                Matanuska-Susitna Borough
Chapter 1 - Streets                                                    Public Works Department

additional standards and criteria such as off-site improvements when deemed appropriate to
protect the safety and welfare of the public.

1.1.6 Right-of-Way (ROW) Development

Many different uses must be accommodated in any development or redevelopment of a
ROW. The ROW should include enough space to incorporate the following segments of use
if a designer chooses to incorporate them: landscaping, a sidewalk and/or multi-use/bike
path, a utility strip, snow storage area, and roadway (pavement and drainage). In addition to
this DCM, the MSB Trails Plan should be reviewed when designing the ROW.

While reconstructing existing streets, the goal should be to meet or exceed current design
standards. Sometimes conditions, such as limited ROW, may prevent the practical
application of all design standards. In such cases, a written approval from the Borough
Engineer is required for deviations from the current design. Additional ROW is often
required in roadway reconstruction projects to provide for cut/fill slopes, utility relocations,
intersection reconfigurations, and landscaping.




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Design Criteria Manual                                                 Matanuska-Susitna Borough
Chapter 1 - Streets                                                     Public Works Department

1.2    Functional Classifications

1.2.1 Objectives.

The role that a roadway serves within the overall transportation network defines its function.
Some roads serve travel over extended distances while others channel traffic to centers of
community activity. Other roads primarily provide access to abutting properties.
Classification establishes a hierarchy of road function and the mobility versus access
character. Classification is typically used to determine road design standards and roadside
development restrictions.

Roadway typical section characteristics are determined by the classification of the roadway
in the OSHP. When a new roadway without classification is proposed, it shall receive a
classification from the Borough Engineer, based on projected traffic volume, origin and
destination, and other considerations. Roads that provide connectivity to adjoining parcels
may require larger ROW or greater design geometry, even if the current development only
requires construction to a lower street standard. The general roadway classifications consist
of arterial, collector, and local streets. Mountain access streets are a special classification to
be used where extreme topography dictates. Access design should comply with the proposed
classifications in the OSHP and with final alignments approved by the Borough Engineer.

Arterials are designed to carry large volumes of traffic at an efficient speed. Local streets
serve the terminal ends of a trip. Collector streets gather and distribute trips between local
streets and the arterial. This can be further broken down by saying that the arterial’s main
function is mobility, the local street’s main function is access, and that collectors offer a
balance of access and mobility. Street class mobility and access functions are shown in
Figure 1-1 below.




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Design Criteria Manual                Matanuska-Susitna Borough
Chapter 1 - Streets                    Public Works Department

                         Figure 1-1




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Design Criteria Manual                                              Matanuska-Susitna Borough
Chapter 1 - Streets                                                  Public Works Department

1.2.2 Arterials

High-volume roads, specifically designed to carry interregional traffic for example, between
two cities. Design criteria including typical sections and ROW requirements are determined
on a case specific basis.

   1. Major arterials

       FUNCTION – Major arterial routes permit rapid and relatively unimpeded traffic
       movement throughout the City, connecting major land use elements as well as
       connecting to outside communities.

       PLANNING CHARACTERISTICS – Major Arterial streets should not bisect
       neighborhoods but should act as boundaries between them. Major Arterial should be
       spaced approximately one (1) mile apart. See Street Standards Technical Criteria
       Chart for intersection spacing criteria. Local streets should not intersect with Major
       Arterial. Street parking is not allowed on Major Arterial. Regulation of Traffic shall
       be accomplished through the use of traffic signals and channeling. Major Arterial
       streets are intended to have continuous medians.

       7,000 ADT and above.

   2. Minor arterials

       FUNCTION – Minor Arterial streets permit relatively unimpeded traffic movement
       and are intended for use on those routes where four moving lanes and one left-turn
       lane are required but where a Major Arterial cross section would not be warranted.

       PLANNING CHARACTERISTICS – Minor Arterials should be employed where
       traffic demand dictates. Minor Arterials should be spaced approximately one (1) mile
       apart and should, where possible, be continuous. Minor Arterial should act as
       boundaries between neighborhood areas. Intersections with Collectors streets should
       be at least one-quarter (1/4) mile apart. See the Street Standard Technical Design
       Criteria Chart for allowable intersection spacing. No street parking is allowed on


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Design Criteria Manual                                                Matanuska-Susitna Borough
Chapter 1 - Streets                                                    Public Works Department

       Minor Arterial streets. Regulation of traffic shall be accomplished through the use of
       traffic signs, signals, and channeling. Traffic signals will normally be required at
       intersections. Access from streets of lower classification will be permitted, but in all
       cases will be controlled by traffic control devices. Direct access to abutting property
       is not permitted unless no other access is reasonably available. Minor Arterial streets
       are intended to have continuous medians.

   3. Parkway/Minor Arterial

       FUNCTION – Parkway Arterial routes provide the same function as Major Arterial
       streets, with the allowance for higher speeds, additional lane potential, higher
       volumes, and provisions for multi-modal enhancement.

       PLANNING CHARACTERISTICS – Parkway Arterial streets should act as
       boundaries between neighborhoods, and should be spaced greater than one (1) mile
       apart. They provide for major multi-modal opportunities along major transportation
       corridors.

1.2.3 Collectors

   1. Major Collector

       FUNCTION – Major Collector streets shall be designed to permit relatively
       unimpeded traffic movement and are intended for use on those routes where four (4)
       moving lanes are required but where a larger classified street is not warranted.

       PLANNING CHARACTERISTICS – Major Collector streets should be employed
       where traffic demands dictate. Major Collector streets are intended for use in
       commercial/industrial areas or high density residential. See the Street Standards
       Technical Design Criteria Chart for allowable intersection spacing. Street parking is
       not allowed on Major Collector streets. Access from streets of lower classification
       will be permitted, but in all cases will be controlled by traffic control devices. Direct
       access to abutting property is not permitted unless no other access is reasonably
       available. Regulation of traffic shall be accomplished through the use of traffic signs,

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Design Criteria Manual                                                        Matanuska-Susitna Borough
Chapter 1 - Streets                                                            Public Works Department

       signals, and channeling. Traffic signals will normally be located only at intersections
       with Arterial Streets.

   2. Minor Collector

       FUNCTION – Minor Collectors collect and distribute traffic between Arterials,
       Major Collectors, and Local streets and serve as main connectors within
       communities, linking one neighborhood with another.

       PLANNING CHARACTERISTICS – Minor Collectors are generally intended for use
       within residential neighborhoods or to connect smaller neighborhoods. Intersections
       with other Collector and Arterial streets should be at least one-quarter (1/4) mile
       apart. Regulation of traffic shall be accomplished through the use of stop signs and
       channeling.

       For subdivision Minor Collector road design, the following chart can be used to allow
       local lot access onto Minor Collectors:


       ADT Level                                   1500-1800         1801-2200         2201-2700
               2701 +

       Percentage of Lots Allowed Access                    20%                  10%                5%
       0%

       (Note: Number of lots allowed access to the Minor Collector is based on the number of lots fronting
       the Minor Collector road within that subdivision.)


       Minor Collectors collect and distribute traffic between arterials, major collectors,
       local streets, and serve as main connectors within communities, linking one
       neighborhood with another. Minor collectors are generally intended for use within
       local neighborhoods or to connect smaller neighborhoods. Intersections with other
       collector and arterial streets shall be a minimum of one-quarter (1/4) mile apart when
       possible. Regulation of traffic shall be accomplished through the use of approved
       traffic control measures.




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Design Criteria Manual                                                 Matanuska-Susitna Borough
Chapter 1 - Streets                                                     Public Works Department

   2. Collectors Within an Industrial/Commercial Area. The main function of a collector
        street in an industrial/commercial area is to conduct traffic from industrial and
        commercial businesses that experience significant truck traffic to arterials. Land
        access is a higher function of collectors in industrial or commercial areas than of
        standard collectors. Design speeds should be appropriate for the surrounding land use
        but should not exceed 45 mph. Lane widths for collectors within industrial/
        commercial areas should be large enough to provide the proper level of service,
        depending on the roadway traffic conditions.

1.2.4   Local

        Traffic carried by local streets primarily should have an origin or a destination within
        the neighborhood, and are designed to discourage through traffic. Local roads are
        typically accessed from minor collectors or other local roads and can also be designed
        as cul-de-sacs. This is the lowest level street. Local streets provide direct access to
        individual properties. They are intended to carry the least amount of traffic at the
        lowest speed and to provide access to individual properties for motorized vehicles,
        bicycles, and pedestrians. They carry traffic that has its destination or origin on that
        street or from within the local neighborhood. Whenever possible, local streets should
        not intersect major collectors or arterial streets.

   1. Local – Commercial/Industrial

        FUNCTION – Local streets serve local traffic and have low traffic volumes. Traffic
        carried by Local streets should have an origin or a destination within the
        neighborhood, and are designed to discourage through traffic. Local streets are
        typically designed to connect to Collector streets, although they can also be designed
        as cul-de-sacs or to provide connectivity to adjacent subdivisions.

        CHARACTERISTICS – Local Commercial/Industrial streets are intended for
        commercial/industrial developments. These streets may intersect Major Collectors in
        some situations, but should not intersect with an Arterial Street. On-street parking,




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Design Criteria Manual                                               Matanuska-Susitna Borough
Chapter 1 - Streets                                                   Public Works Department

       backing, or loading maneuvers shall not be allowed. Traffic control shall be provided
       using stop signs at all intersections.

   2. Local Frontage Streets - Commercial

       FUNCTION - Frontage streets are required as an alternative to allowing access to or
       from lots along existing or proposed collectors or higher classification
       streets. Frontage streets shall be classified and designed to conform with the design
       standards and service restrictions of collector streets as anticipated average daily
       traffic may dictate. According to the American Association of State Highway and
       Transportation Officials (AASHTO), for satisfactory operation with moderate-to-
       heavy traffic volumes on the frontage streets, the intersection shall be a minimum of
       150 feet and preferably 300 feet from the adjoining right- of-way line. The design
       year traffic volumes, turning movements, vehicle storage, and signal phasing should
       all be analyzed when determining the outer separation distance.

   3. Local – RESIDENTIAL

       FUNCTION – Local streets shall provide local traffic and have low traffic volumes.
       Traffic carried by local streets should have an origin or a destination within the
       neighborhood, and are designed to discourage through traffic. Local streets are
       typically designed to connect to collector streets, although they can also be designed
       as cul-de-sacs or provide connectivity to adjacent subdivisions.

       CHARACTERISTICS – Local residential streets are intended for use in medium to
       high density residential neighborhoods. Local streets should not intersect Major
       Collectors or Arterial streets.

       Parking may be allowed on both sides of local residential streets, providing additional
       roadway width is provided. Traffic control shall be provided using stop signs at all
       intersections.

       CHARACTERISTICS – Local residential streets are intended for use in medium to
       high density residential neighborhoods. Local streets should not intersect Major

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Design Criteria Manual                                                 Matanuska-Susitna Borough
Chapter 1 - Streets                                                     Public Works Department

       Collectors or Arterial streets. Parking shall be allowed on both sides of local
       residential streets. Traffic control shall be provided using stop signs at all
       intersections.

   4. Local – PIONEER

       FUNCTION – Rural residential play a significant importance to economic
       development in rural portion of the MSB. They typically are the initial roads within
       an unsubdivided land. Their road status tends to change over time as development
       progresses around the initial road. Thus the need for increase ROW for future road
       upgrades to Collector streets.

       CHARACTERISTICS – Pioneer residential streets are intended for use out side the
       MSB Core Area in low to very low-density residential neighborhoods.

   5. Local - HILLSIDE/ MOUNTAIN

       FUNCTION – Hillside/Mountain streets are typically designed to address the
       requirements of steep terrain. An increased ROW is needed to account for slopes and
       guard rail.

       CHARACTERISTICS – Hillside/ Mountain streets are intended for use in areas
       where the original ground is 15-24% cross slope and areas with cross slopes 25% or
       greater.

1.2.5 Traffic Volume Determination

Determine trip generation from methods established in the Institute of Transportation
Engineers (ITE) Trip Generation Manual, as applicable. A Traffic Impact Analysis (TIA)
may be required as part of any development project.

Right of way width determination is dependent upon the intended land use: local,
commercial, or mixed use. The highest trip generation factor for the potential land use will be
used unless a density restriction or limitation exists or is created. This is to help ensure
sufficient right of way is provided at full build out.

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Design Criteria Manual                                                           Matanuska-Susitna Borough
Chapter 1 - Streets                                                               Public Works Department

To determine road classification, local development will generate 10 trips per dwelling unit.

A TIA is required to be generated by a licensed civil engineer for commercial development
with greater than 100 trips per peak hour. Common factors are provided below for
determining the peak hour trips.

Traffic impacts may be mitigated by multiple accesses, improved driving surfaces (paving),
turn lanes, and traffic signals.

                       Table 1-1: Average Trip Generation Factors

 Type of Development                                                 Peak Hour Trips
 Apartments with 7 or more units                                     1.00 trips per dwelling unit
 Hotels and Motels                                                   1.00 trips per room
 Schools (All)                                                       0.25 trips per student
 Industrial Facilities                                               0.50 trips per employee
 Hospitals                                                           1.36 trips per bed
 Nursing Homes                                                       0.36 trips per bed
 Clinics *                                                           2.48 trips per 1,000 ft2
 General Office Buildings                                            2.00 trips per 1,000 ft2
 Medical Office Buildings                                            3.90 trips per 1,000 ft2
 Civic Centers                                                       2.85 trips per 1,000 ft2
 Post Offices, DMV and other high-turnover public services           11.0 trips per 1,000 ft2
 Discount Stores                                                     6.97 trips per 1,000 ft2
 hardware Stores                                                     5.20 trips per 1,000 ft2
 Shopping Centers (per ft2)

      0-50,000 ft2       Trips=


      50,000-1,500,000 ft2        Trips=3.22 x (size of Shopping Center in ft2/1,000) + 614

 Service Stations                                                    6.00 trips per pump (two hoses)
 Car Wash                                                            132 trips per site
 Truck Stop                                                          88.00 trips per site
 Supermarket                                                         15.70 trips per 1,000 ft2
 Convenience Market                                                  47.00 trips per 1,000 ft2
 Wholesale Markets                                                   0.52 trips per 1,000 ft2
 Furniture Stores                                                    0.10 trips per 1,000 ft2
 Banks                                                               30.00 trips per 1,000 ft2
 Savings and Loan offices                                            9.70 trips per 1,000 ft2
 Insurance Offices                                                   2.40 trips per 1,000 ft2




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Design Criteria Manual                                                                    Matanuska-Susitna Borough
Chapter 1 - Streets                                                                        Public Works Department

* Average number of one-way trips generated (or attracted) by a given facility during the peak generating (or attracting)
hour of the facility. This peak may or may not coincide with peak traffic flow on the adjacent street. Where the average
time of the motorist at the generator (or attractor) is less than one hour, the flow is half into the facility and half out.
(Example: Truck stops with 88 peak hour trips per site would represent 44 inbound and 44 outbound trips.) Trips based on
area are based on gross leasable floor area. Information taken from ADOT Highway Preconstruction Manual.

Consult with the Borough Engineer to determine if a TIA is required and what information must be
included in the analysis.




From Table of Contents. Need to either add text below to each section or delete:

1.2.7 Design Elements

1.2.8 Pedestrian/Vehicle Separations




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Design Criteria Manual                                                              Matanuska-Susitna Borough
Chapter 1 - Streets                                                                  Public Works Department

           Roadway Requirements

1.3.1 Design Criteria for arterials are usually determined by the designing agency. Due to
the various needs and level of service desired for the facility, AASHTO criteria will be used
in designing those facilities.

1.3.2 Roadway Characteristics

Table 1-2 describes roadway characteristics of collector and local roads. Actual sizing is
determined on a case-by-case basis.

                                    Table 0-2: Road Characteristics
                                                                         COLLECTOR
                                                                        MAJOR       MINOR
              Overall Design Parameters
              Design Speed                                      MPH         50          40
              Posted Speed                                      MPH         45          35
              Stopping Sight Distance                           FT         425         305


              Number of Lanes Traveled                          EA              2           2
              Travel Lane Width                                 FT          12          11
              Paving Width                                      FT          16          12
              Width of Shoulder                                 FT              4           2
              Roadway Width                                     FT          32          26
              Right-of Way Width                                FT         100          80


              Horizontal Alignment
              Horizontal Centerline Radius(1)                   FT         850         500
              Maximum Super-elevation                               %           6           6
              Minimum Tangent Between Curves(2)                 FT         100         100


              Vertical Alignment
              Maximum Centerline Grade                              %       10          10
              Rate of Curvature (Crest and/Sag) K-Value                   61/79       44/64
              Minimum Flow Line Grades                              %       0.5         0.5


              Intersection Design
              Minimum Distance Between Intersections                %      600         300



              Notes:
              1. Horizontal Radius may decreased based on ADT Present, ADT20
              with DPW approval
              2. Tangent Length maybe reduced base on topography, ADT Present,
              ADT20 with DPW approval
              3. See typical section for Mountain Access


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1.3.3      Typical Sections

The cross-sections shown on the following pages illustrate typical characteristics of paved
and unpaved collector roadways.




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Design Criteria Manual                                          Matanuska-Susitna Borough
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            Figure 0-1: Collector Road Typical Section – Major Collector Paved




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Design Criteria Manual                                          Matanuska-Susitna Borough
Chapter 1 - Streets                                              Public Works Department




           Figure 0-3: Collector Road Typical Section – Major Collector Unpaved
                            (PLACEHOLDER: NEEDS CORRECT PDF)




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Design Criteria Manual                                          Matanuska-Susitna Borough
Chapter 1 - Streets                                              Public Works Department

            Figure 0-4: Collector Road Typical Section – Minor Collector Paved
                            (PLACEHOLDER: NEEDS CORRECT PDF)




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Design Criteria Manual                                          Matanuska-Susitna Borough
Chapter 1 - Streets                                              Public Works Department




           Figure 0-5: Collector Road Typical Section – Minor Collector Unpaved
                            (PLACEHOLDER: NEEDS CORRECT PDF)




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1.3.4 Local

                                           Table 0-3: Road Characteristics
                                                                                LACOL
                                                                       LOCAL      MOUNTAIN
                    Overall Design Parameters
                    Design Speed                                MPH      30           30
                    Posted Speed                                MPH      25           25
                    Stopping Sight Distance                     FT      200          200


                    Number of Lanes Traveled                    EA       2            2
                    Travel Lane Width                           FT       10        varies(3)
                    Paving Width                                FT       11        varies(3)
                    Width of Shoulder                           FT       2         varies(3)
                    Roadway Width                               FT       24        varies(3)
                    Right-of Way Width                          FT       60           80


                    Horizontal Alignment
                    Horizontal Centerline Radius(1)             FT      250        varies(3)
                    Maximum Super-elevation                     %        4            4
                    Minimum Tangent Between Curves(2)           FT      100          100


                    Vertical Alignment
                    Maximum Centerline Grade                     %       10        varies(3)
                    Rate of Curvature (Crest and/Sag) K-Value           19/37       19/37
                    Minimum Flow Line Grades                    %        0.5         0.5


                    Intersection Design
                    Minimum Distance Between Intersections      %       150          150



                    Notes:
                    1. Horizontal Radius may decreased based on ADT Present, ADT20 with
                    DPW approval
                    2. Tangent Length maybe reduced base on topography, ADT Present,
                    ADT20 with DPW approval
                    3. See typical section for Mountain Access


Types

Local streets are low volume, low speed streets without curb and gutter and minimum
shoulders, where access to residences, not mobility, is the primary function. Residences will
primarily front the road, and there may be a high percentage of pedestrians and bicyclists,
particularly children, sharing the ROW with vehicles. Lane widths can vary depending on
the amount of available ROW and the ADT the roadway receives.

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Table 1-_ describes roadway characteristics of local-local streets, but actual sizing is
determined on a case-by-case basis.

Divided

[Reserved]

Alleys

Alleys are not anticipated outside of municipal areas. See City criteria for further
information on alleys.

Typical Section

The following figures show the typical section characteristics for a local street.




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Design Criteria Manual                                            Matanuska-Susitna Borough
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                         Figure 0-_: Local Road Typical Section




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Design Criteria Manual                                          Matanuska-Susitna Borough
Chapter 1 - Streets                                              Public Works Department

Mountain Access Discussion

                     Figure 0-_: Mountain Access Road Typical Section




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Design Criteria Manual             Matanuska-Susitna Borough
Chapter 1 - Streets                 Public Works Department




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Design Criteria Manual             Matanuska-Susitna Borough
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           [Reserved]

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Design Criteria Manual             Matanuska-Susitna Borough
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Design Criteria Manual                                              Matanuska-Susitna Borough
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Typical Section

Figure 1-_ shows the typical section characteristics for a mountain access road.

Requirements for Paved Streets

[Reserved]




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Design Criteria Manual                                         Matanuska-Susitna Borough
Chapter 1 - Streets                                             Public Works Department

__
                     Figure 0-_: Mountain Access Road Typical Section




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Design Criteria Manual                                                Matanuska-Susitna Borough
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Soil Investigation Standards

Objective

A subsurface soils investigation shall be performed on all road, drainage, and development
projects within the MSB. The primary purpose of a soils investigation is to provide the
Engineer with information on the Engineering properties of the subsurface soils, water table,
and moisture conditions throughout the project. Soils data are also helpful to the
construction engineer and contractor in determining constructability and costs.

Soil investigation in sub-arctic regions is a significant design concern due to the potential of
frost heave and its damaging effects on road systems. Because frost action is to a great
degree dependent on soils types and moisture content, the Engineer must have adequate
information on both of these items to design durable roads. These issues are critical because
of the extreme geological variations in soils stratigraphy and water tables found in the
Matanuska-Susitna area. The objective of this section is to assist the Engineer in determining
what soils information is necessary in a subsurface investigative report and outlining a format
for presentation of the report to the MSB Engineering Division.

In addition, when the subject site is known or suspected to be on or near a former fill, dump
site, or when the previous use of the land is suspected to have potentially caused soil or
groundwater contamination, the Borough Engineer may require test holes at a greater
frequency as well as outside of the existing or proposed project limits to ensure that
construction does not occur on poor or contaminated soils. If visual or aromatic observations
of petroleum hydrocarbons are made and suspected, complete the appropriate soils and/or
groundwater testing and analysis to quantitatively establish the presence or absence of
petroleum constituents.

Test Holes

The spacing and depth requirements for test holes must be determined based on existing site
conditions and project needs. Each project shall be examined carefully to determine
adequate spacing requirements. Throughout the project length, the offset location of test
holes shall be varied relative to the street centerline.


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Test holes shall be located outside of utility trenches. When organic material is present or
encountered, the test hole shall be extended a minimum of 4 feet below the bottom of the
organic layer. When permafrost is expected or encountered, the test hole depth shall be
extended as deep as 40 feet. In both cases, the recommendations of a qualified Engineer
shall be obtained to determine the minimum depth requirements.

For investigations in existing roadways, obtain at least one representative bulk sample from
the existing subbase material, with a mechanical analyses performed.

If groundwater is encountered, then the high groundwater level needs to be determined.
Generally, seasonal high groundwater is determined between April and November.

Testing Standards for Usable Material

Mechanical analyses for each typical soils unit group must be performed, and the soils must
be classified in accordance with ASTM D2487, Unified Soil Classification System. In
addition, gradations must be performed on representative bulk samples in the upper 5 feet of
test holes with any obvious fill material of significant quantity (1 foot or more) being
recorded and analyzed. Moisture content shall be determined as appropriate for the soils
encountered. The test hole number and depth of sample on each mechanical analysis shall be
noted. Information from any mechanical analysis shall be attached to the test hole log and
shall be included in the soils investigation report.

Soils Investigation Report

A soils investigation report is required for every road project to document the investigative
process and soils conditions. Soils investigation reports shall bear the stamp and signature of
a professional engineer licensed in the State of Alaska.

   1. Report Text

       The text of a soils report should contain, but is not limited to, the following
       information:

       Map of the project location and description of the local topography.


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       Brief geologic review of the local vicinity.

       Synopsis of the exploration methodology and equipment, including sampling, testing,
           and drilling equipment.

       Brief description of the laboratory and field-testing program, including the name of
           the testing agency.

       Descriptions of the subsurface soils properties, including classification in accordance
           with the latest edition of ASTM D2487; grouping of soils into major types;
           distribution of soil types; frost penetration if exploration was conducted during
           the freezing period; and the location and nature of any permafrost encountered.

       f) Notation of encountered depth of groundwater and estimated seasonal groundwater
           fluctuations.

       g) Narrative about conclusions and recommendations pertinent to the design of the
           proposed improvements, including the effects of freezing and thawing of the soils.

   2. Test Hole Logs

       Visual logs are required for each test hole. The following information describes the
       minimum detail required on each log:

       a) Date of test hole, test hole number, horizontal location (stationing and centerline
           offset), and elevation.

       b) Record groundwater level(s) while or after exploration. If no groundwater is
           encountered report this finding on the log.

       c) Top and bottom of each stratum, measured from the existing surface. For each
           stratum provide description of soil density and fines content.

       d) Soil moisture content (percentage), if determined at each sampling interval.




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       e) Frost classification of each stratum (by soils type). (review this after structural
           section)

       f) For samples on which gradations are determined, percent passing the No. 200
           sieve.




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Design Criteria Manual                                                Matanuska-Susitna Borough
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Design Criteria

General Objectives

Design elements are the building blocks of road composition. As roads serve different
purposes, depending on their location and surrounding development, they should be designed
appropriately for their function and location.

The ultimate goal in the design of streets is to construct roads that are safe, functional, and
durable. The criteria identified in this section are intended to guide the Engineer. Specific
areas of street design that are discussed include design speeds, lane widths, vertical design
requirements, horizontal design requirements, and structural fill requirements. Adherence to
these standards or those of the AASHTO is required.

Design and Posted Speed

Design speeds for different street classifications are provided in Table 1-2, Design Elements.
It should be noted that the design speed is not usually the posted speed. The objective in
design of any engineered facility used by the public is to satisfy the public’s demand for
service in a safe and economical manner for all users. Therefore, the facility should
accommodate as many demands as possible and also should not fail under severe or extreme
traffic demands. Roadways should be designed to operate at a speed that satisfies the
anticipated need of the users. It is important that the design speed slightly exceed the posted
speed on collector streets and roads as this will provide a margin of safety for drivers driving
at the speed limit in unfavorable conditions such as inclement weather. Design and posted
speeds will vary depending on the purpose of the facility. The difference between design and
posted speeds will also vary depending on the type of facility; the difference typically varies
from 5 to 10 miles per hour (mph). Design and posted speeds are noted in Table 1-2, Design
Elements.




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Lane


The lane width influences the safety and comfort of driving. Narrow lanes force drivers to
operate their vehicles closer laterally than would otherwise be desired and can have a
negative impact on capacity. Wider lanes provide desirable clearances between wider
commercial vehicles traveling in opposing directions. Many roads see little truck traffic, and,
as such, narrower lanes may be appropriate within many developments where the street has
little or no chance for increased traffic than what is projected for the current development.
Lane widths for streets are provided in Table 1-2, Design Elements.

Shoulder

Shoulders are the portions of the roadway adjacent to, and on the outside edge of, traveled
lanes that serve several purposes. The primary purposes they serve may be:

   1. Space for disabled vehicles or refuge for vehicles that momentarily stop (mail,
        maintenance, buses, delivery, provide clearance for emergency service vehicle
        passage).

   2. Space for evasive maneuvers to avoid encroachment accidents.

   3. Improved corner sight-distance at intersections and in horizontal curves.

   4. Improved capacity by allowing uninterrupted flow.

   5.   Space for bicyclists and pedestrian separation when there is inadequate ROW to
        separate pedestrian facilities.

   6. For paved roadways, all except 1’ of the shoulder must be paved.

Where bicyclists and pedestrians are to be accommodated, the designer should refer to the
AASHTO publication, Guide for the Development of Bicycle Facilities, for additional
guidance.




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UTILITIES

All potential utility companies must be involved in the early stages of a project’s
development. When existing utility facilities conflict with proposed road improvements, the
designer must analyze the alternatives available for resolving the conflict early in the design
study or preliminary design efforts. If the analysis indicates the need for relocation, the
relocation efforts shall be accomplished in accordance with MSB Title 11.

The horizontal design objectives found in Section 1.9.5 must be considered to evaluate the
cost effectiveness of the relocation versus alternative approaches to the roadway design. The
MSB Engineering Division shall be advised about the utility conflicts and the result of the
utility relocation analysis at the earliest time possible in the design effort. This will allow
resolution of relocation design issues with the appropriate utility before the final design-
phase activities proceed. Approval of the Borough Engineer shall be obtained for any
proposed deviation from standard road improvement locations for utilities.

The size and location of required services shall be coordinated with each utility. Before final
road surfacing, installation of the services from the utility main line to the property line shall
be provided or conduit shall be installed to facilitate future utility services.

The location of utilities are to be encouraged within established utility easements wherever
possible. The owner or the representative will be responsible for satisfying any conflicts that
may occur in the request for easements from any utility company. Easements are to be clear
of wells, septic systems, homes, decks, buildings or other structures; unless the developer has
obtained a “Non-Objection to Easement Encroachment” from the utilities. Utility easements
are to be fully useable for utility installation where installation equipment can safely work.

GENERAL UTILITY PLACEMENT:

The portion of back slopes or foreslopes that extends into the utility easement should not
exceed 4:1. These limits are necessary for construction equipment to install and maintain
utility infrastructure.




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A fifteen-foot utility easement is typically needed outside both sides of the road right of way
to allow for utility installation and maintenance.

Separation and installation of utilities shall be in accordance with applicable national
standards.

If the city has standards for installing utilities, those standards must be met.

Utility facilities placed within the road right of way:

Utility facilities should generally be located as shown in the attached drawing entitled
locations for utilities.

Utility facilities paralleling the ditch line may not be placed closer than four feet from the
ditch bottom.

No shallow utility installation paralleling the road surface will be allowed within the road
surface or shoulder areas due to road compaction and/or designated fill requirements. This
restriction is not applicable to underground road crossings.

Underground road crossings require compaction according to the requirements of the permit
issued to the utility by the borough.

Horizontal Design Standards

    1. Objectives

        Because of ROW constraints, the flexibility in horizontal alignment of the driving
        surface is often limited. However, the designer should strive to meet the following
        prioritized horizontal alignment design objectives for the driving surface when
        preparing plans.

        a) Satisfy AASHTO stopping sight distance standards for design speeds

        b) Provide clear visibility triangles at street intersections




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       c) All proposed streets shall intersect at right angle unless topography and other
           limiting factors of good design and safety require otherwise

       d) Where streets intersect with other streets that are not in alignment (opposite of
           each other), the street’s centerline shall be offset in accordance with Table 1-2,
           Design Elements.

       e) Utility easements shall be provided as necessary for utility service

       f) Minimize slope easement or ROW acquisition costs

       g) Match existing property grades to provide a safe access and reduce property
           impacts

       h) Reduce construction costs associated with retaining structures

       i) Generally, the construction centerline should be located on the ROW centerline.
           However, this may not be appropriate if multiple transportation facilities are
           planned. In these instances, safety, utility placement, practicability of
           construction and maintenance considerations shall be the determining factors.

       j) Reduce unnecessary project costs including maintenance while keeping
           consistent with other design objectives

   2. Horizontal Curves

       The guidelines established by the AASHTO manual, A Policy on the Geometric
       Design of Highways and Streets, also known as the “Green Book,” shall be used
       when the project cannot meet all the horizontal design objectives specified herein.
       Minimum horizontal curve centerline radii are provided in Table 1-2, Design
       Elements.

       The Green Book provides the Designer with information on the use of super-elevated
       curves that may reduce the required radii. The maximum cross slope on a super-
       elevated curve is 6 percent. Transitions into super-elevations shall conform to


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Design Criteria Manual                                               Matanuska-Susitna Borough
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       recommendations of the Green Book. The impacts of the super-elevation on drainage
       and access shall also be carefully considered.

       Minimum tangent length between horizontal curves is provided in Table 1-2, Design
       Elements.

   3. Visibility Triangles

       When designing streets, impairment of the visibility of motorists at intersections must
       not be allowed. AASHTO establishes minimum approach and departure sight
       triangles.

       Although desirable at high volume intersections, approach sight triangles are typically
       not needed at stop- or signal- controlled intersections. Since most intersections in the
       MSB are at least stop-controlled, only departure sight triangles are addressed herein.

       Departure sight triangles are illustrated in Figure 1-10. Limited improvements, such
       as street light or signal poles may encroach into these areas if the Borough Engineer
       approves the variation. Figure 1-11 provides methods for calculating visibility sight
       lines on horizontal curves.

       To enhance traffic operations, intersection sight distances that exceed stopping sight
       distances are desirable along the major roadway. Figure 1-11 provides desirable
       sight distances at stop-controlled intersections sufficient for a stopped driver on the
       minor road approach to depart from the intersection and enter the major road.




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             Figure 0- 10: Intersection Departure Sight Triangles (Stop Control)




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Design Criteria Manual                                                               Matanuska-Susitna Borough
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Height of eye = 3.5 feet

Height of object = 2.0 feet

Line of sight is 2.75 feet above CL
inside lane at point of obstruction

                                                           S = Stopping sight distance (feet)
                                                                         C
                                                           R = Radius of Linside land (feet)
                           Stopping Sight
Design Speed               Distance                        M = Middle ordinate (feet)
(mph)                      (feet)
25                         155
30                         200
35                         250
                                                           _
40                         305                                 _
45                         380
50                         425
55                         495                             Formula applies only when S is equal to or less than
60                         570                             length of curve.
65                         645

(Adapted from AASHTO)

Figure 0-11: Horizontal Curve Visibility Sight Lines


          Figure 1-11 intersection sight distances are based on the following conditions:

                   time gaps in major road traffic

                   left turns from the minor road

                   passenger-car design vehicle

                   2-lane major road with no median, and

                   grades 3 percent or less


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        In no case should the intersection sight distance be less than the stopping sight
        distance. For other conditions or different types of traffic control, the Engineer shall
        consult the latest edition of AASHTO’s Green Book.

    4. Snow Storage

        Snow storage and removal shall always be considered in designing streets. Methods
        of snow disposal vary depending on the location of the street. The Borough Engineer
        shall be consulted to resolve snow-removal issues relative to design and particular
        project location. .

        No activity shall occur within the ROW that would impede snow storage unless
        authorized by an encroachment permit.

    5. Clear Zone

        The clear zone is the total roadside border area, starting at the edge of traveled way,
        available for safe use by errant vehicles. The desired width of the clear zone is
        dependent on the traffic volume, design speed, and roadside geometry. Where there
        is a curb, a minimum horizontal clearance of 1.5 feet should be provided beyond the
        face of curb to obstructions. Where there is not a curb, the clear zone width shall be
        determined in accordance with AASHTO’s Roadside Design Guide.

Vertical Design Standards

Vertical design standards must be carefully considered to ensure safety concerns for stopping
sight distance and winter road conditions. Vertical design standards are established for
grades, vertical curves, cross slopes, cut slopes, and fill slopes.

    1. Objectives

        Vertical design objectives are intended to achieve the following:

        a) Provide adequate stopping sight distances for design speeds

        b) Provide safe street grades



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       c) Provide safe driveway grades

       d) Provide for adequate road drainage while minimizing storm drain structures

       e) Minimize retaining structure costs

       f) Maintain standard cross slopes

       g) Minimize slope easement or ROW acquisition costs

       h) Minimize crests and sags

       i) Minimize project costs while maintaining consistency with other design
           objectives

       j) Provide adequate cover over utilities

       k) Minimize use of valley gutters

       l) Avoid costly utility relocations

       Vertical design criteria detailed in this section must be adhered to on all projects that
       involve street design within the Borough.

   2. Street Grades

       The following design criteria shall be used for street grades:

       a) A desirable maximum street grade is 6.0 percent, however if topographical
           constraints or other conditions exist, then:

           (i) for streets of collector or higher classification the maximum road grade is 8.0
               percent;

          (ii) for all roads less than collector classification, the maximum road grade is 10.0
               percent;




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           (iii) the Borough Engineer may approve occasional road grades exceeding the
                 above criteria by up to 2.0 percent on short, straight sections not exceeding
                 250 feet in length. However, grades exceeding the maximum road grade are
                 not permitted in intersection approaches within 150 feet of intersection
                 centerlines or curves.

                    A “straight section” shall mean a section of roadway with no horizontal
                    deflection;

           (iv) Immediately before and after a section with greater than 10 percent grade,
                 there shall be a minimum 500-foot “straight section” of roadway with grades
                 that does not exceed 10 percent. This requirement is not applicable to
                 ascending/descending crest or “hump” vertical curves.

       c) The Borough Engineer-may approve a radius of curvature less than specified in
           Table 1-2 Minimum Horizontal Curve Radii (Section 1.9.5) contingent upon:

           (i)     the maximum grade through the horizontal curve is 5.0 percent,

           (ii) the maximum road grade uphill from a horizontal curve with radius less than
                 specified in Table 1-2 Minimum Horizontal Curve Radii (Section 1.9.5) is
                 5.0 percent for at least 250 feet beyond the point of curvature/tangency to
                 allow for acceleration and braking operations;

           (iii)only with the installation of appropriate signs.

       d) The maximum grade on cul-de-sac bulbs, measured in any direction, is
           5.0 percent.

       e) With the exception of (f) below, the maximum grade within 50 feet of a “T”
           intersection is 4% and 7% within a through intersection.

       f) The maximum grade of a local street at an intersection with a collector street is
           2.0 percent within a distance of 30 feet from the back of curb or the edge of
           shoulder line of the fully developed primary street.

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       g) The minimum grade around a curb return is 0.50 percent.

       h) The minimum Portland cement concrete valley gutter grade is 0.50 percent.

       i) The minimum asphalt concrete valley gutter grade is 1.0 percent.

       j) The minimum grade in the curb and gutter along eyebrows and cul-de-sacs is
           0.5 percent.

       k) On intersecting local streets, match the intersecting centerline crowns.

       l) Match street grades for local street intersecting a collector street to the edge of
           pavement or valley gutter on the collector street.

       m) In the case of intersecting collector streets, give preference or primacy in street
           grades to the street with the higher designation in accordance with the OSHP, or
           to the street with the higher traffic volume when the streets have the same
           functional classification.

       n) Driveway profiles – Driveway profiles shall conform to MSB’s policy for
           “Driveway Standards” in Appendix 1A.

           (i) Drainage. Driveways shall not drain onto the high side of super-elevated or
               “tipped” road sections.

           (ii) Sidewalks. If a sidewalk or walkway is crossed, the driveway profile may not
               exceed the slope of the sidewalk.

           (iii)Vertical Curves. Vertical curves should be symmetrical and as flat as feasible.
               Crest vertical curves should not exceed a 3.25-inch hump in 12-foot chord,
               and sag vertical curves should not exceed a 2-inch depression in a 12-foot
               chord. Driveway vertical curves shall not have humps or depressions
               exceeding 3.6 inches in a 12-foot chord.




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           (iv) Landings. Driveways shall have landings or landing areas. Landing length is
               dependent on anticipated vehicle usage and shall conform to MSB’s policy for
               Driveway Standards in Appendix 1A.

           (v) Pedestrian Areas. Where curbed driveway returns intersect a pedestrian way,
               provide appropriate pedestrian access ramps that meet current Americans with
               Disabilities Act (ADA) standards.

   3. Cross Slopes

       The primary function of a cross slope on a street section is to direct drainage to the
       edge of a street. In most cases, a street is crowned in the middle and slopes to the
       outside edge. The standard cross slope is 2.0 percent for paved streets and 3.0 percent
       for recycled asphalt pavement (RAP) streets and for gravel roads.

       When super-elevations are being considered, the design guidelines established by
       AASHTO with a maximum cross slope of 6.0 percent shall be applied.

       When standard cross-sections do not allow street grade objectives to be met, the
       Engineer may utilize a tipped street cross-section. However, the maximum cross
       slope on tipped streets is 4.0 percent because of potential safety hazards related to
       icing conditions. Tipped street sections should receive careful consideration with
       respect to drainage.

   4. Vertical Curves

       Grade breaks are only acceptable when the algebraic difference between the varying
       street grades is 1.0 percent or less for collector or higher and 2.0 percent for local
       streets. Vertical curves shall be used for transitions when the change between varying
       street grades exceeds 1.0 percent or on high-speed streets and roads. High-speed
       streets are defined as having a speed limit greater than or equal to 50 mph.

       Vertical curves should be separated by a tangent grade of at least 25 feet. Sag vertical
       curves may be shortened by using the factor equation L = AV²/46.5 (where L = length
       of curve, in feet; A = algebraic grade difference; and V = speed in mph), provided

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       that the entire vertical curve is adequately illuminated. As a minimum, the design of
       vertical curves shall use the design speeds established in Table 1-2, Design Elements,
       and the vertical curve charts provided in Figures 1-8 and 1-9.




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(Adapted from AASHTO)

Figure 0-2: Crest Vertical Curve Lengths




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Design Criteria Manual                             Matanuska-Susitna Borough
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_


_
(Adapted from AASHTO)

Figure 0-3: Sag Vertical Curve Lengths




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       Vertical curves are only allowed through intersections when they meet the street
       grade design objectives provided in Section 1.9.4-1 and with approval by the
       Borough Engineer.

       To minimize drainage problems, the length and location of a vertical curve shall
       be selected to minimize areas with shallow grades and eliminate areas with flat
       grades. Curb grades at catch basins shall be adjusted as necessary to maintain
       positive drainage and to avoid flat ground. Positive drainage refers to a minimum
       of 0.50% for a paved surface and 1% for a recycled asphalt or gravel surface.

   5. Cut and Fill Slopes

       In many cases, road construction requires substantial cut and fill slopes adjacent
       to the road. The primary concerns on cut and fill slopes are stability and safe
       access to adjacent property. MSB driveway grade standards are provided in
       Appendix 1A. A Driveway Permit is required for all new driveways constructed
       within borough ROW.

       In evaluating cut and fill slopes, the maintenance of the slope in terms of mowing
       and snow removal shall be considered. In some cases, a low retaining wall or
       sidewalk retaining wall may be preferable to extensive property re-sloping,
       particularly if landscaping, fences, or structures would be disturbed. In all cases
       the design and locations of the retaining walls must be approved by the Borough
       Engineer.

       As a rule, cut and fill slopes shall not exceed 2.0-foot horizontal to 1.0-foot
       vertical. However, the Borough Engineer may approve steeper slopes if the
       Designer provides adequate information to verify slope stability for the steeper
       slopes. For all cut and fill slopes, appropriate erosion and sediment control
       measures such as topsoil, seeding, and/or erosion control matting must be
       provided. Use of adequate erosion and sediment control measures is required.
       Erosion and sediment control concerns are addressed in more detail in Chapter 2.

       When cut and fill slopes fall outside of the ROW, a slope easement is required.

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       When groundwater seeps from embankments or cut slopes are observed during
       the course of project development, whether design or construction, the Contractor
       and Engineer shall ensure that adequate controls are implemented to prevent
       erosion, instability of the roadway and sloughing of the slopes. Increased ditch
       capacity shall be provided in the drainage design to prevent glaciation issues
       during the winter months, including but not limited to drainage and encroachment
       into the roadway.

Design Elements


_
Figure 0-?4: Typical Right-of-Way Development (NOTE: need to move) road, pedestrian
facilities, utilities


Design Components

Streets consist of many separate components that are not all applicable in every situation.
However, when these elements are used, the following general guidelines apply. Specific
guidelines for the following components may be found in applicable AASHTO and ITE
publications. Any variations to the following guidelines must be approved by the
Borough Engineer.

Curb and Gutter

The type and location of curbs affect driver behavior and thus will have impacts on the
safety and utility of a roadway. Curbs serve the following purposes:

    1. Drainage control

    2. Roadway edge delineation

    3. Delineation of pedestrian walkways

    4. Assistance in orderly roadside development



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   5. Access control

Curb and gutter design must meet AASHTO requirements for clear zones.

The following types of curbs are installed in the MSB, consisting of five primary types
and two variations. See Figure 1-_.

           Mountable curb and gutter is for use along collector roads as well as in
           commercial and industrial areas.

           Expressway curb and gutter shall be used on medians and traffic islands.

           Rolled curb and gutter shall be used on local roads.

           Depressed curb and gutter is for use on curb cuts (driveway access) with
           standard curb and gutter.

           Gutter is used on local roads to deliver runoff safely to a storm drain structure
           or drainage outlet.




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                         Figure 1-10 “Curb and Gutter Details”




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   1. Curb Returns

       Because the potential for pedestrian and vehicle conflicts is particularly high at
       street intersections, reduction of potential hazards shall be given careful
       consideration. In particular, the size of the curb return radius and the length and
       location of pedestrian crossings must be addressed.

       A curb return radius is a function of road classification and design vehicle type
       (Figure 1-12).

       Local local curb returns shall be designed to have a 30-foot radius from the face
       of curb or edge of traveled way.

        A 40-foot radius from the face of curb or edge of traveled way shall be provided
       for all intersections with collector or arterial streets.

       To accommodate larger vehicles in commercial or industrial areas, the above-
       specified curb radii may be increased..

[Reserved]
Figure 1-_: Standard Curb Return Radii

       The curb return shall be designed to provide pedestrian safety that meets the ADA
       requirements. (See ADA Checklist to be inserted here). Curb returns shall
       accommodate pedestrian needs to the extent practical.

   2. Curb Cuts

       Curb cuts may be used at low points in the roadway vertical profile to facilitate
       drainage to roadside ditches. Refer to ADOT/PF Standard Drawings for proper
       design of curb cuts.

   3. Driveways

       The frequency and location of driveways are functions of street or road
       classification, type of local use, and the location of existing structures on adjacent


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       property. Driveway width is a function of anticipated use. Driveways must be
       designed in accordance with the latest version of MSB’s policy for Driveway
       Standards in Appendix 1A.

   4. Medians

       The primary function of a roadway median is to separate opposing traffic
       movements and control left-turn movements. Medians may also serve to provide
       drainage areas and/or enhance aesthetics. The use of medians requires approval
       by the MSB Public Works Department.

       The following criteria apply to median design:

       The minimum width of a raised median is 4 feet from face of curb to face of curb.
       The width of a depressed median shall be designed to accommodate roadway
       drainage as per AASHTO.

       Vertical curbs should not be used along high-speed roadways (design speeds
       greater than 45 mph). Raised medians on high-speed roadways shall be
       constructed of mountable curb and gutter.

       The median nose shall be depressed to reduce safety hazards for oncoming traffic
       and to safely accommodate maintenance vehicle movements.

       A raised median that separates a left-turn lane from the opposing traffic shall
       extend the full length of the left-turn pocket.

   5. Guardrails

       When warranted, guardrails shall be located in accordance with the AASHTO
       design guide. Guardrails shall not be used where they present a hazard equal to or
       greater than the obstacle that prompted consideration of the guardrail. The
       AASHTO standards shall be used as a further guide for guardrail placement (refer
       to ADOT&PF Standard Details).




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   6. Retaining Structures

       In some cases, roadway design cannot avoid use of retaining structures to support
       the road base or a cut/fill bank. All available design alternatives to reduce the
       necessity for installing retaining structures shall be considered. Where no
       alternative solutions exist, materials that are resistant to deterioration and provide
       for cost-effective construction shall be incorporated into the design.

       Retaining structures less than 4 feet in height used to avoid slope encroachment or
       to protect adjacent structures must use applicable ADOT&PF Standard Drawings
       or a site-specific design shall be developed. Adequate drainage must be provided
       behind the structure. A registered engineer must prepare and seal the design of all
       retaining structures.

   7. Cul-de-sacs, Turnarounds and Eyebrows

       When topography and traffic circulation permit, a cul-de-sac street may be
       designed to provide vehicular turnaround for a dead-end street. A street
       terminating as a cul-de-sac is only allowed when the length of the street from the
       centerline of the intersecting through street to the radius point of the cul-de-sac
       bulb does not exceed 800 feet.

       A cul-de-sac street shall be terminated with a turnaround that has a minimum
       radius of 40 feet (measured to edge of pavement) and a minimum return radius of
       50 feet.

       Cul-de-sacs, turnarounds and eyebrows shall be designed in accordance with
       Figures 1-15 and 1-16.

   8. Pedestrian Facilities

       While a roadway shoulder does provide pedestrian separation from vehicles, it is
       preferred that additional separation is provided behind the curb or edge of
       shoulder. Pedestrian facilities should be installed where heavy pedestrian traffic
       (20 pedestrians per hour or greater) is anticipated. The minimum width of

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       pedestrian facilities should provide for a comfortable width for side-by-side
       walkers and pedestrian-wheelchair. The location of pedestrian crossings at
       intersections is dictated by the presence of pathways or sidewalks and by federal
       requirements under the ADA. Where pedestrian and vehicular needs conflict, the
       Borough Engineer shall be contacted to resolve the conflict and determine the
       design preference.

   9. Pedestrian/Vehicle Separations

       Where possible, the sidewalk should be separated from the traveled way to
       provide additional separation between the pedestrian and the roadway. The
       separation provides a more comfortable and safer pedestrian environment along
       streets. Separations provide buffer from immediate vehicle noise, exhaust, dust,
       and backsplash, and allow pedestrian facilities to be clear of roadway snow
       storage and glaciation during winter. For these reasons, separations are an
       important factor in the level of use and the functionality of the public facility.
       This is especially important if a collector or higher classification road is also a
       school-walking route, and special efforts are made to keep the path clear of snow.
       The ability to provide adequate separation is sometimes hampered by lack of
       adequate ROW. Separations shall be designed according to AASHTO
       requirements.




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       The MSB Engineering Division may permit a cul-de-sac street to terminate with
       an alternative turnaround that meets fire code when such a design is required by
       extreme environmental or topographical conditions, or unusual or irregularly
       shaped tract boundaries, or when a street is intended to be extended at a future
       date.

       Permanent no-outlet streets shall terminate in the form of a cul-de-sac. Permanent
       cul-de-sacs are allowed on local streets only.

   10. Driving Surfaces

       Asphalt: The material and thickness requirements for a street surface are
       dependent on the volume and type of traffic. A minimum asphalt pavement
       thickness of 2 inches shall be used on local streets. Primary streets, such as
       collectors and arterials, may require a pavement thickness of 3 and 4 inches,
       respectively. Structural pavement design calculations shall be submitted to the
       Borough Engineer to substantiate any reduced pavement thickness. In no instance
       shall the thickness be less than 2 inches.

       Gravel: The material and thickness requirements for a street surface are
       dependent on the volume and type of traffic. The gravel-surface course which
       measures at least 6 inches of 2-inch minus shall be used on all gravel roads. Bill
       will write material types.

   11. Private Improvements in Public Rights Of Way (ROW) or Easements for Public
       Access

       Public rights of way and easements for public access may include both improved
       and unimproved areas. All private improvements in these public areas are at risk
       unless otherwise permitted by the Borough.

   12. Pedestrian Facilities

       Pedestrian facilities shall be provided in accordance with Chapter 4 of the DCM.
       Need to work on this.



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Driveways

   1. State Highways

       Access to state highways is regulated by ADOT&PF. Encroachment permits for
       access to state highways are available from ADOT&PF, and it is the
       responsibility of the developer to obtain permits whenever construction within
       ADOT&PF ROW is anticipated.

   Borough Streets

       All connections to MSB streets must first be authorized by the MSB Engineering
       Division. It is desirable to keep the number of access points per lot to a
       minimum. Snow removal operations need to be a consideration when planning
       access points.

       Traffic volume will determine conditions of the driveway permit. When the use
       of any property or its access operation increases driveway traffic volume
       significantly, or a significant change in a particular directional characteristic (such
       as left turns), the MSB may re-evaluate the design, number, and location of access
       points to verify public health, welfare and safety to determine if a driveway
       upgrade and/or relocation is required.

   Access Points

       No points of access shall be approved for non-local parking or loading areas that
       require backing maneuvers into a public street ROW.




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           (i) Provision of Access

               If a property has frontage on more than one street, access is permitted only
               on those street frontages where standards contained in this manual and
               other MSB regulations can be met (referenced in 1.9.8-2.b)(iii).

               If a property cannot be served by any access point meeting these
               standards, the Borough Engineer will designate one or more access points
               based on traffic safety, operational needs, and conformance to as many of
               the requirements of these guidelines as possible.

           (ii) Restriction of Turning Movements

               Where necessary for the safe and efficient movement of traffic, the MSB
               may require that access points be geometrically designed to provide for
               only limited turning movements.

           (iii)Number of Access Points

               One access point per property is permitted, unless a project site plan or
               circulation plan is provided to and approved by the Borough Engineer.
               The circulation plan must indicate that more than one access is required to
               adequately handle driveway volumes and that additional driveways are not
               detrimental to traffic flow on adjacent public roads.

               Where a property has access to more than one road, access is generally
               limited to the lowest volume road where the impacts of a new access
               would be minimized. Access on other higher volume roads may be
               denied.

               Temporary access may be granted to undeveloped property before a final
               development plan is prepared if access is needed for construction or
               preliminary site access. A General Construction permit is required prior to
               construction of the temporary access. Permit applications can be obtained
               by contacting the MSB Public Works Department or on-line at


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               http://www.matsugov.us/PublicWorks/. Temporary accesses are subject
               to removal, relocation, or redesign after final development plan approval.

   2. Criteria for Requiring Speed Change Lanes

       Speed change lanes are required according to the National Cooperative Highway
       Research Program Report 279.



Road Structural Fill Design

Objectives

In sub-arctic environments such as the MSB, the primary consideration in the structural
design of a road is the potential impact of freezing and thawing on the road surface. The
material in the subgrade (existing ground beneath the road’s structural section) is
considered frost susceptible when it is likely to develop detrimental ice segregation. The
adverse impacts associated with ice lens formation can be significant. The degree of
impact is also influenced by the amount of moisture in the subgrade. The primary goal in
the structural design of a road is to reduce freezing and thawing impacts to a level that
allows for the desired roadway life. Reduction of these impacts is best accomplished by
providing an adequate classified structural fill above the subgrade as well as adequate
drainage facilities in order to minimize frost heave.

In general, finer-grained soils potentially may contain amounts of unfrozen water at
subfreezing temperatures that are larger than the amounts in coarser soils. Because of
this, the higher the content of fine-grained soils the greater the likelihood of adverse ice
lens development and the higher the frost susceptibility. Materials containing, by weight,
more than 3 percent finer than 0.02 millimeters in diameter are generally considered frost
susceptible. The degree of ice lens development is also related to the size range of the
soil voids. For example, some uniform sandy soils may contain as much as 10 percent
finer than 0.02 millimeters without being frost susceptible.

The borrow material types described in the ADOT&PF Standard Specifications and the
borrow material identified in Section 1.7.3 have been developed to address these

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concerns. The following criteria are mandatory design objectives when frost-susceptible
material is encountered in the subgrade:

   1. Thermally induced capillary action is the upward migration or drawing of
       moisture that is created by the generation of negative pore pressures within the
       freezing zone of frost-susceptible soil. This excess moisture is detrimental to the
       structural embankment and manifests itself in the form of ice lenses in a frost-
       susceptible subgrade beneath the structural fill (subbase) when subjected to
       freezing temperatures. The adverse impacts of these ice lenses is a non-uniform
       heaving of pavement surface during the winter months and a loss of strength of
       effected soils during the spring thaw-weakened period. Ice segregation has
       demonstrated the ability to contaminate borrow material over the long term. The
       formation of ice lenses must be mitigated by limiting the frost penetration into
       frost-susceptible subgrade. This is best accomplished by providing an adequate
       depth of borrow material or the combination of borrow material and insulation.

   2. The upward migration of fine-grained materials from a highly frost-susceptible
       subgrade into the borrow material, or pumping, must be prevented. This can be
       accomplished through the installation of geotextile fabric or other engineered
       system. The structural fill section(s) (subbase) must be of sufficient depth to
       distribute and minimize tire pressure over thaw-weakened soils.

       Differential frost heaving must be minimized by providing extended transitions
       between structural fill sections of varying depths and/or structural fill and
       insulated sections. Underground utility trench excavation sidewall angles may be
       no steeper than 1-1/2 horizontal to 1 vertical (1-1/2:1).

Material Specifications

Refer to the latest version of the ADOT&PF Standard Specifications for Highway
Construction for the various types of approved aggregate base and subbase materials for
the roadway structural section within the MSB.




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Design in Organic Soils

All unsuitable material must be removed from the road subgrade. As a rule, when
removing organic materials from beneath a road surface the lateral extent of the
excavation beyond the back of curb (or edge of shoulder for gravel roads) shall be
roughly equivalent to the depth of unsuitable materials removed (i.e., if 10 feet of
organics are removed from below a road way, the horizontal extent of the excavation
beyond back of curb shall be 10 feet). Failure to excavate outside of the pavement
footprint may result in a spreading road base fill that will eventually lead to pavement
distress. Prior to placement of borrow material, the Contractor must provide an as-built
survey showing the excavation of unsuitable material has been extended sufficiently
beyond the edge of the road improvements.

Road Structural Section Design Methods

The depth of structural fill is primarily a function of the frost classification of the
underlying soil. Descriptions of these classifications are provided in Table 1-3.
Structural fill depths (subbase) are exclusive of the pavement and base course.
Additional depth of subbase may also be required if there is a high water table or a near-
saturated soil condition, unless methods are proposed to alleviate the water problem.




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                            Table 0-_: Frost Design Soil Classification


                                                     Percentage Finer Than        Typical Soil Types
Frost                                                   0.02 Millimeter           Under Unified Soil
Group                    Soil Type                         by Weight             Classification System

        a. Gravels                                          0 to 3             GW, GP
NFS
        b. Sands                                            0 to 3             SW, SP

 F-1    Gravelly soils                                      3 to 10            GW,GP,GW-GM,GP-GM

        a. Gravelly soils                                  10 to 20            GM, GW-GM, GP-GM
 F-2
        b. Sands                                            3 to 15            SW, SP, SM, SW-SM, SP

        a. Gravelly soils                                  Over 20             GM, GC

 F-3    b. Sands, except very fine silty sands             Over 15             SM, SC

        c. Clays, PI>12                                       --               CL, CH

        a. All silts                                          --               ML, MH

        b. Very fine silty sands                           Over 15             SM
 F-4    c. Clays, PI<12                                       --               CL, CL-ML

        d. Varved clays and                                   --               CL, CL-ML
           other fine-grained, banded sediments               --               CL, CH, ML, SM


   Regardless of the frost classification, the Complete Protection Method may always be
   used to determine the depth of borrow material and backfill required for the structural
   section. This method involves the removal of all frost-susceptible materials within the
   subbase down to the calculated frost penetration depth and replacement of the frost-
   susceptible material with the appropriate borrow material and backfill.

   There are two circumstances in which the calculated depth of the borrow material and
   backfill subbase depth may be modified: (1) significant quantities of usable non-frost
   susceptible material exist within the excavation that may be supplemented for borrow
   material and backfill; and (2) the embedment of insulation board in the subbase of the
   structural section is determined to reduce the required depth of borrow material and
   backfill sufficiently to make it a more cost-effective design.

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In both cases, these materials may be factored in to the calculation of borrow material and
backfill depth.

When the underlying soil type is frost group F-1, the minimum depth of structural fill
shall be 1.75 feet. When the underlying soil is F-2, F-3, or F-4, the Limited Subgrade
Frost Penetration Method may be used in lieu of the Complete Protection Method. The
Limited Subgrade Frost Penetration Method attempts to restrict surface movements to
levels that will not adversely affect road surface life or quality.

For the Limited Subgrade Frost Penetration method, the depth of structural fill shall be
calculated based on a maximum frost penetration into the subgrade of 10 percent of the
overall pavement structural section (pavement, base course, and subbase borrow
material). The calculated maximum freeze/thaw depths used to develop the structural
section must be provided along with all supporting documentation. Care should be taken
to use the most accurate soil properties and realistic moisture contents possible.

The BERG 2 computer model, the Microcomputer Estimation of Freeze and Thaw
Depths and Thaw Consolidation, or Multilayer User-Friendly Thermal Model in 1
Dimension (MUT1D), or another program approved by the MSB shall be used to
calculate the total frost depth. The BERG 2 and MUT1D computer programs provide for
the use of insulation in the backfill to reduce the depth of fill required. Insulation
approved for roadway use is discussed in Section 1.10.6.

Geotextile Fabrics

An engineer faced with the task of designing a street in an area with frost-susceptible
soils and high moisture content can reap many benefits from use of geotextile fabric in
the design. Where high soil moisture content occurs in F-3 and F-4 soils, geotextile
fabric should be incorporated into the structural design section to separate borrow
material from frost-susceptible soils.

The first step in selecting an appropriate fabric from the many available is definition of
application requirements. Geotextile fabrics can be used for the following reasons in
street designs:

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    1. Separation - acts as a separator to prevent the pumping of frost-susceptible
        subgrade material into the gravel backfill, minimizing the contamination of gravel
        backfill and maintaining its support strength.

    2. Load Distribution - provides structural strength to a soft, weak, and frequently wet
        subgrade. The fabric helps mitigate pavement and subgrade deformation caused
        by wheel loading and works to extend the service life of the pavement.

    3. Confinement - maintains the original shear strength of the compacted gravel by
        confining the gravel backfill, which allows the subgrade to support the wheel
        loads placed on it.

ADOT&PF Standard Specifications shall be followed for geotextile fabrics.

Insulation

Insulation may be used in the construction of streets where the subgrade is determined to
be frost-susceptible and reduction in the depth of the gravel backfill, as required by the
Limited Frost Penetration Method, is desired for economic reasons. The use of insulation
is not intended to prevent the freezing front from reaching the subgrade; it is intended to
minimize the depth of subgrade freezing below the borrow material by providing partial
thermal protection and a more uniform freezing depth. Other factors, such as the
interception and removal of water by a drainage system, are also important and are
covered in Chapter 2 of this manual.

The ADOT&PF Standard Specifications establishes standard construction specifications
for improvements that use insulation within the street ROW.

Research conducted by ADOT&PF has shown the following to be acceptable guidelines
for the use of rigid insulation:

    1. Use of only high-density polystyrene board with a minimum compressive strength
        of 60 pounds per square inch and a maximum water absorption of 0.10 by
        volume;


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   2. Placement of a minimum cover of 18 inches of gravel fill over the insulation to
       protect the insulation from heavy wheel loads during construction and to
       minimize frost formation on the pavement surface;

   3. Extending the limits of the insulated section adequately beyond the heave zone to
       avoid causing bumps where the frost-susceptible material is not insulated. In
       addition, if more than one layer of boards is used, insulation thickness shall be
       gradually stepped down.

Accessibility Requirements

All new construction and alterations within the MSB ROW must be designed to be
accessible for all pedestrians in accordance with the ADA when applicable. The
complete Americans with Disabilities Act Accessibility Guidelines (ADAAG), which is
part of the regulations enforcing ADA, is available online from the U.S. Architectural and
Transportation Barriers Compliance Board (Access Board) at www.access-board.gov.
Designs that include pedestrian facilities within MSB ROW shall conform to the version
of ADA Guidelines for Accessible Public Rights-of-Way in effect at the time of submittal.

The following are examples of some design elements covered under current ADAAG or
that have been determined in federal court to apply:

   1. New or widened road (all pedestrian elements, including curb ramps, sidewalk
       cross slope, driveway cross slope, clearance around utilities, pedestrian access to
       adjacent commercial properties, and accessible pedestrian construction detours).

   2. Bus stop (pad size, curb ramp at nearest cross street, bench style, protruding
       object restrictions, and connection to sidewalk).

       Surface rehabilitation only (new and complying curb ramp for every street and
       alley crossing that has both sidewalk and curb, unless there is an existing curb
       ramp that meets all ADA standards).




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For information purposes, a design checklist for accessible sidewalks and street crossings
is included in Appendix 1B. This checklist does not cover all requirements, and the
designer should become familiar with the ADA and the latest available ADAAG.

Bill: multiply the current ADT below by 1.5 to show the correct current standard.
Subcollector starts at 601. See Gary’s notes.




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