REDESIGN OF I-76 AND I-77 IN AKRON by RLGwsP

VIEWS: 24 PAGES: 12

									                                                                                                 DRAFT

                           REDESIGN OF I-76 AND I-77 IN AKRON
                       INCLUDING THE CENTRAL INTERCHANGE
                                  Purpose and Need Document
1.0        INTRODUCTION
           1.1   History
                 The Purpose and Need for the Redesign of I-76 and I-77 in Akron Including the
                 Central Interchange (Akron Central Interchange Project) evolved from the I-76/80
                 Corridor Study completed in 2004. That study, covering 78 miles of ODOT
                 maintained I-76 and I-80 in five northeast Ohio counties, identified 10.6 miles of I-
                 76 in Summit County as needing capacity, safety and maintenance improvements
                 between the study year and 2025. Based on those findings, a more detailed study
                 of the 10.6-mile corridor was conducted to identify an improvement concept to be
                 carried forward into Steps 5 through 8 of ODOT’s Major Project Development
                 Process. The findings of the more detailed study were documented in the I-
                 76/AMATS Major Investment Study approved by the Akron Metropolitan Area
                 Transportation Study (AMATS) Policy Committee in February 2004. Those MIS
                 findings were incorporated into an ODOT strategic plan for the corridor, the
                 Summit I-76 Strategic Plan, which identified a program for carrying out the
                 improvement concept plus reconstructing 0.6 miles of I-76 from the Medina
                 County line to SR 21.

                 The most critical section of the 11.2 mile I-76 MIS/Strategic Plan corridor was the
                 Central Interchange and a segment of I-76/I-77 extending approximately two miles
                 to the west through the SR 59 interchange. ODOT confirmed those findings with
                 the initiation of the Akron Central Interchange Project in late 2004. Critical
                 transportation needs from the I-76 AMATS MIS/Summit I-76 Strategic Plan for
                 that project area are discussed in the following sections and identified on
                 associated graphics.

           1.2   Study Area
                 Figure 1 shows the study area for the Akron Central Interchange Project. The
                 study area is within the City of Akron approximately a mile south of the Central
                 Business District. The immediate study area includes older residential and
                 commercial zones. These commercial areas focus on the Broadway Street-Main
                 Street and Grant Street/Wolf Ledges Parkway corridors and include the CSXT
                 railroad mainline through the City of Akron. Several government facilities,
                 including the main Post Office for Akron, the Summit County Jail and the County
                 Engineers office, and the City of Akron Water Department, are within the study
                 area or immediately adjacent to it. This development is in the approximate center
                 of the study area and is served by the Broadway-Main and Grant/Wolf Ledges
                 Interchanges.


                                                  1 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                           URS
                                                                                                DRAFT

                 To the east and west, the project area becomes more residential. The
                 neighborhoods consist of older working class homes. The population includes
                 relatively large numbers of minorities and low-income households. On the west
                 end of the project area is Summit Lake Park and the Ohio and Erie Canal
                 recreational and open space.

                 The Akron Central Interchange Project corridor presently provides access to a
                 commercial corridor extending along Broadway-Main and Grant St./Wolf Ledges.
                 The development includes a variety of government and private sector activities
                 including manufacturing, wholesale and some retail oriented business. The quality of
                 development ranges from relatively modern commercial buildings to vacant and
                 underutilized brownfield properties. Meetings with the public, stakeholder groups
                 and government officials indicate there is interest in the area for new business and
                 redevelopment. Maintaining good access is very important in maintaining the
                 economic viability of existing business and encouraging the redevelopment of
                 brownfield properties.

                 The Grant St./Wolf Ledges interchange provides access to:

                  The main US Post Office for the Akron area.
                  A commercial district north of the freeway along Voris, Wolf Ledges and Grant
                   Streets which the University of Akron is promoting for additional development—
                   University Place.
                  Major University of Akron parking facilities along Exchange Street via Grant and
                   Wolf Ledges.
                  The Summit County Jail between Wolf Ledges and Grant Street south of I-76
                  A commercial district south of I-76 and east of the CSX railroad which includes
                   brownfield properties for redevelopment.
                  Indirectly, the Summit County Engineer’s office and maintenance yard in the
                   southwest quadrant of the Central Interchange.
                  Indirectly, the City of Akron Water Department service center in the northwest
                   quadrant of the Central interchange.

                 The Broadway-Main Street interchange serves the arterial streets which are the
                 historical southern approach to Downtown Akron. The City of Akron recently
                 completed a major renovation of a 0.5 mile section of this six lane one-way pair
                 between I-76 and Downtown Akron. The interchange provides access to:

                  The south side of the Downtown Akron Business District.
                  The western edge of the University of Akron including parking facilities.
                  Canal Park, the Akron Arrows minor league baseball park.
                  An economic development business district focused on the former B. F. Goodrich
                   tire complex (Canal Place) but including a 2 mile section of the Broadway Main
                   corridor between Downtown Akron and I-76.
                  An old industrial/commercial district along Broadway/Main south of I-76 to the
                   CSX RR which includes older buildings and vacant brownfield properties.
                                                 2 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                            URS
                                                                                                      DRAFT

                      The remaining Akron area operations of Bridgestone Tire successor to Firestone
                       Tire located in the old Firestone Tire Complex.
                      The north end of a very large brownfield area, including portions of the old
                       Firestone complex, south of Firestone and along the CSX Railroad corridor.

                     Figure 9 highlights the locations of the economic and cultural destinations described
                     above and the existing local access interchanges from the freeway system.
           1.3       Functional Classification
                     I-76 and I-77 are principal arterials, Interstates, and on the National Highway
                     System. SR 8 and SR 59 are principal arterials, other freeways and expressways.
                     SR 8 is also on the National Highway System. The Broadway Main one-way pair
                     is a principal arterial. All other roadways are minor arterials, collectors or local
                     streets. No other roadways in the project area are included in the National
                     Highway System. The entire Akron Central Interchange Project is within the
                     urbanized area and all functional classifications include the urban caveat for design
                     considerations.

2.0        PURPOSE AND NEED
The following summarizes the purpose and need based on the identified conditions in the corridor:

                    Increase capacity and improve the level of service to at least LOS “D” in the design
                     year
                    Improve safety and reduce crash rates throughout the corridor to the State Mean Rate
                     or less..
                    Provide a facility that meets Ohio Department of Transportation standards for
                     horizontal and vertical geometry for the functional classification of project roadways.
                    Provide a facility that does not negatively impact the City of Akron’s plans for
                     maintaining and expanding employment opportunities in the Broadway-Main and
                     adjacent Grant/Wolf Ledges corridors.
           2.1       Capacity/Level of Service
           The capacity of a roadway section can be affected by the geometry of the roadway,
           the number of access points and the basic number of lanes. Capacity is reflected in the
           level of service (LOS). Level of service is a commonly used indicator of highway
           performance. Levels of service range from A, which indicates unrestricted free flow,
           to F, which indicates high congestion and generally restricted operating speeds. In the
           Central Interchange, there are segments that do not have the basic capacity to carry
           the volume of traffic that currently desires or is anticipated to use the segment in the
           future. Figures 2 and 3 show 2001 peak hour traffic and Figures 4 and 5, projected
           2030 peak hour traffic.

           The following sections do not have the basic number of lanes to carry the existing or
           anticipated volumes at an acceptable level of service.


                                                      3 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                               URS
                                                                                                      DRAFT

            The I-77 SB ramp in the Central Interchange is striped for a single lane. (This was a safety
             measure instituted several years ago.) The lane in 2001 carried 1790 vehicles including 80
             trucks in the PM peak hour or 89 % of capacity for the traffic mix and a 45 MPH design speed
             ramp roadway. This ramps is at the LOS D/E divide today.

            The I-77 SB ramp in the Central Interchange is anticipated to carry 1950 vehicles including 100
             trucks or need 110 % of capacity of its current capacity in the PM peak hour in 2030. This ramp
             will be at LOS F.

            The I-77 NB ramp in the Central Interchange is striped as a single lane ramp. The lane
             carried approximately1800 vehicles including 150 trucks or 93 % of capacity in the AM
             peak hour in 2001 for a 45 MPH design speed ramp roadway. The ramp is at LOS E.

            The I-77 NB ramp in the Central Interchange is anticipated to carry 2010 vehicles
             including 200 trucks or need 103 % of capacity in the 2030 AM peak hour. The ramp
             will be at LOS F.

            SR 8 NB in the 2030 AM peak period is anticipated to carry 4640 vehicles including 330
             trucks or need 111 percent of capacity. The ramp will be at LOS F.

            SR 8 SB in the 2030 PM peak period is anticipated to carry 4550 vehicles including 220
             trucks or need 106 percent of capacity. The ramp will be at LOS F.

           The WB I-76 exit to Grant-Wolf Ledges backs onto the freeway in the AM peak
           period. This in part reflects intersection capacity at the local street terminal.

           The amount of access affects operations and the level of service. Merging, diverging and
           weave actions require more space and the capacity of a lane or combination of lanes is
           reduced. Furthermore, turbulence created by merging or diverging traffic may extend up to a
           quarter mile either side of the access point. The design guidelines on interchange spacing
           helps smooth traffic flow and eliminate overlapping of turbulent conditions.

           The current design guideline for interchange spacing on urban freeways is one mile.
           However, on I-76 EB within the 2.2 project corridor there are six separately identified
           interchanges and ten entrance and exit ramps; on I-76 WB within the 2.2 mile project
           corridor there are six identified interchanges and eleven entrance and exit ramps.

           The number of interchanges and the general design, which treats the ramps and their freeway
           terminal for each interchange sequentially (exit, followed by entrance followed by exit vis-à-
           vis a braided or scissors design), results in poor levels of service. Figures 6 and 7 show the
           current and design year level of service through the corridor. Many of the major weaving
           areas operate at LOS D in peak periods in the peak direction today. By the design year, these
           weaving sections operate at LOS E.




                                                     4 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                                URS
                                                                                                       DRAFT

           2.2    Safety/Crash Analysis
           Crashes can be linked to a number of causes including driver related issues (such as
           excessive speed for conditions or physical impairment); weather; lighting; roadway capacity;
           roadway geometry; or, weaving and merging actions relating to access. A roadway project
           can have only minor impacts on many driver related causes. There is little control over
           weather and some weather conditions are best addressed by maintenance actions. However
           highway improvements can reduce crashes typically related to capacity and geometric
           deficiencies.

           The majority of the crashes within the corridor, rear end, sideswipe, and fixed object, are
           typical for congested and/or poor geometric conditions. Rear end accidents are usually
           highest on ramps to local streets because of the stop and go conditions. However congested
           mainline sections also have many rear end crashes. Sideswipe crashes are typical of lane
           changing actions and would be anticipated on segments near ramp terminals However, on
           congested sections beyond ramps, aggressive drivers may change lanes abruptly without
           confirming whether or not there is a vehicle in their ‘blind spot.”

           Fixed object crashes are universally off-the-road crashes. Hitting a vehicle stopped in the
           roadway is a vehicle crash. Crashes where something that fell off a preceding vehicle is hit
           are eliminated, like crashes with animals, because they are often beyond the control of the “at
           fault” driver. Off the road crashes reflect poor basic roadway geometry such as low speed
           ramps in a high speed environment. However, in a congested corridor with narrow shoulders
           such as the project area, actions to avoid crashes with other vehicles may result in hitting the
           median or guardrail.

           In the 22.4 directional miles of I-76 within the corridor covered by the I-76 Reconstruction
           and Upgrade Strategic Plan, 14 of the 23 high crash locations** or 61 percent occurred in the
           4.4 directional miles of the Akron Central Interchange Project area. Of the 12 highest crash
           locations in the I-76 Reconstruction Corridor, 8 or 67 percent occurred within the I-76
           Central Interchange project area. The following are the highest crash locations (shown on
           Figure 8) within the Akron Central Interchange Project corridor:

            The Grant/Wolf Ledges Interchange area EB had crashes at a rate of 3.61 per MVM or
             230 per mile. Rear end crashes accounted for 55.1 percent of the total, sideswipe 21.7
             percent and fixed object 13.0 percent.



*Based on ODOT guidance, high crash locations are those locations with a crash rate greater than 1 crash per
million vehicle miles traveled or 50 crashes per directional mile. Crashes were identified to 0.1-mile (520
foot) segments by direction, eliminating animal related and falling object crashes per ODOT practice.
Crashes coded to a cross street at a ramp terminal were eliminated; i.e. only crashes on the ramp are included.
Rates were compiled on 0.3 mile or greater segments. Highest crash locations have a rate of 1.5 crashes per
MVM and more than 75 per mile.



                                                    5 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                                 URS
                                                                                                       DRAFT



            The Grant/Wolf Ledges Interchange area WB had crashes at a rate of 3.09 per MVM or 197 per
             mile. Rear end crashes accounted for 50.8 percent of the total, sideswipe 22.0 percent and fixed
             object 16.9 percent.

            The EB approach to the SR 59 Interchange had crashes at a rate of 2.00 per MVM or 120
             per mile. Rear end crashes accounted for 44.4 percent of the total, fixed object 25.0
             percent and sideswipe 16.7 percent.

            WB I-76 at the SR 59 Interchange had crashes at a rate of 1.95 per MVM or 117 per mile.
             Rear end crashes accounted for 42.9 percent of the total, fixed object 31.4 percent and
             sideswipe 20.0 percent.

            In the Central Interchange I-76 WB had crashes at a rate of 1.88 per MVM or 120 crashes
             per mile. Fixed object crashes accounted for 48.3 percent of the total, rear end 30.0
             percent and sideswipe 13.3 percent.

            In the Central Interchange I-76 EB had crashes at a rate of 1.69 per MVM or 108 crashes
             per mile. Rear end crashes accounted for 40.7 percent of the total, fixed object 31.5
             percent and sideswipe 18.5 percent.

            The Broadway-Main Interchange EB had crashes at a rate of 1.61 per MVM or 90
             crashes per mile. Rear end crashes accounted for 65.5 percent of the total, fixed object
             27.6 percent, and sideswipe less than 5 percent.

            The Broadway-Main Interchange WB had crashes at a rate of 1.56 per MVM or 93
             crashes per mile.

           Five other segments had directional crash rates greater than 1.0 per MVM or 50 per
           equivalent mile.


           2.3     Roadway Deficiencies

           Current ramp terminal separation by the AASHTO Greenbook and ODOT’s Location and
           Design Manual ranges from 500 feet for an exit followed by an entrance ramp to 2000 feet
           for an entrance followed by an exit ramp. ODOT also has design criteria for the length of
           acceleration and deceleration lanes, acceptable horizontal and vertical geometry, and bridge
           clearances. Figure 10 shows the areas of obsolete geometry in the project corridor.



Horizontal design deficiencies include the following:


                                                     6 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                                 URS
                                                                                               DRAFT

            The gore-to-gore distance on EB I-76 from the Dart St. entrance ramp to the Broadway-
             Main entrance ramp is 1450 feet or 150 less than the AASHTO/ODOT recommendation.

            The gore-to-gore weaving distance on EB I-76 from the second Broadway-Main entrance
             ramp to the Wolf Ledges exit ramp is only 800 feet or 800 feet less than the
             AASHTO/ODOT recommended minimum.

            In the Central Interchange, I-76 EB to SR 8 NB, a freeway-to-freeway ramp, is designed
             for 25 mph, a low speed ramp, not a high speed diverge. The deceleration lane at 600
             feet is 200 feet short of the 800 foot minimum deceleration length for a high speed exit.
             In addition, the exit deceleration lane begins only 250 feet from a right hand exit
             (congestion on which backs onto the mainline), is on left hand curve which has been
             preceded by right hand curve with minimal intermediate tangent and is on a slight uphill
             grade partially obscured by an upstream bridge structure. This further contributes to
             driver uncertainty. Thus with the poor ramp geometry and these other factors, traffic
             making the EB to NB move is decelerating in the inside or high speed lane of the freeway
             contributing to observable congestion in the area. Once on the deceleration lane, most
             of the tightest curve is on structure with high parapets. The downstream end of the ramp
             is also on a downhill grade which shortens sight distances.

            In the Central Interchange, the I-76 WB to I-77 SB freeway-to-freeway (Interstate to
             Interstate) ramp is designed for 30 mph, not a high speed diverge. The deceleration lane
             is 600 feet long or 200 feet short of the 800 foot minimum deceleration length for high
             speed exit terminals from the lower speed right lane. The deceleration lane begins
             immediately after an overhead bridge. A portion of the low speed curve is also on a
             bridge structure with high parapets that limit sight distances and contributes to driver
             uncertainty. Thus traffic making the WB to SB move is decelerating in the inside or high
             speed lane of the freeway contributing to observable congestion in the area, often
             extending 0.5 miles upstream to Arlington Ave.

            Grant St./Wolf Ledges entrance to I-76 WB
                      The Grant St./Wolf Ledges entrance to Broadway-Main exit gore to gore
                       distance is 500 feet or less than 1/3 the recommended terminal spacing
                       between an entrance ramp and subsequent exit ramp on a mainline
                       freeway.
                      The Broadway-Main exit was originally two lanes, 24 feet, wide with the
                       outside ramp lane beginning at an auxiliary lane from Wolf Ledges and the
                       outside ramp lane beginning at a drop mainline lane. Although it is
                       currently striped out for one lane, the geometry requires a two lane weave
                       for Grant St./Wolf Ledges traffic to WB I-76.

            The I-76 WB to Broadway-Main exit ramp is currently designed for 25 mph. There is
             only a 400 foot tangent deceleration lane after the gore before the 25 mph loop. Since
             this is a drop lane from a high speed freeway posted at 55 the minimum distance should
             be 410 feet. Given that actual speeds are higher than posted speeds the minimum
             distance should be in the range of 450-500 feet.
                                                 7 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                        URS
                                                                                                   DRAFT


            The drop lane design for WB I-76 to Broadway-Main is inconsistent with AASHTO
             guidance on drop lanes.

            The I-76 WB to Broadway-Main ramp is treated as a free flow condition onto NB
             Broadway but is crossed by a stop sign controlled, minor street. The short sight distance,
             approximately 250 feet, from the curve on structure off I-76 and the intersection creates
             an unsafe condition because such a design is relatively rare and contrary to driver
             expectations.

            The two WB I-76 entrance ramps from Broadway/Main are separated by 400 feet, this is
             less than half the 1000 foot recommended spacing from AASHTO/ODOT.

            The current median shoulder on I-76 in the project area is 9 feet, on a facility with a
             minimum 6 lanes and is predominantly 8 lanes. The lowest truck DDHV in 2001 was 220
             on two segments EB direction in the AM peak; another EB segment had 240 trucks. All
             other segments, in both directions and both AM and PM peak periods, have 250 or more
             trucks. The truck volumes exceed 300 vehicles per peak hour on several segments.
             Current ODOT design criteria is a minimum of 10 feet for a facility with six or more
             lanes and 12 feet if the truck DDHV exceeds 250 vehicles.

           Some overhead freeway bridges in the project area do not meet the current 16.5 foot (17 foot
           preferred) vertical clearance standard. Horizontal clearances are in part reflected in the less
           than standard width shoulders. However, existing pier-to-pier or abutment-to-abutment
           widths on bridges over the freeway may preclude new lanes without replacing the bridge
           structure. Bridges in the project corridor with vertical or horizontal limitations (in feet)
           include:

                                                 Vertical Limitation   Horizontal Limitation
              Hillcrest Ped. Bridge             15.79 & 15.00
              SR 59                             15.97 & 16.21                 EB 59
              Princeton St.                        WB 14.79
              Wolf Ledges                       15.00 & 15.00          EB & WB 70.00
              Grant St.                         15.00 & 15.00          EB & WB 73.25
              Sumner St. Ped. Bridge                 16.25                  86.65
              I-76 WB over SR 8 & I-77               15.25
              I-76 EB over SR 8 & I-77               15.96
              I-76 EB to SR 8 over I-76              15.09
              I-76 WB to I-77 over I-76              15.00
              SR 8 to I-76 EB over SR 8              15.16
              I-77 WB over SR 8                      15.25
              LaFollette St. over I-77               15.41             EB & WB 51.15
              Lovers Lane over I-77                  16.50             EB & WB 71.00
              Wilbeth Rd. over I-77                  16.60             EB & WB 59.00

                                                   8 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                            URS
                                                                                                    DRAFT

           Based on the above information, there is no equivalent alternate route for I-76 to allow for a
           lower bridge clearance in the project corridor. In addition the most reasonable alternate route
           for I-77, across the I-76 Kenmore Leg, has a vertical clearance limitation in the southbound
           direction

           An additional, consideration is the general concept of a left hand exit (as opposed to a
           diverge) in a freeway system. The ODOT’s location and design manual indicates that left
           hand exits are undesirable because they are “contrary to driver expectations.” In northeast
           Ohio, there are a few left hand exits where there is a distinct deceleration lane followed by a
           ramp. One example is the I-77/I-277/US 224 interchange just south of the project area. In
           that interchange, however, the left hand ramps from I-77 NB and SB have a high speed
           design with relatively long deceleration lanes and relatively high speed curves. The left
           hand, low speed ramps in the Central Interchange are the only such design in the ten county
           region.

           Current guidelines for access at Interstate interchanges is “full access” between all directions
           on the local streets to all directions on the Interstate.

           On I-76 there are two partial access (1 / 4 access) interchanges
                         Inman Street: WB I-76 exit only.
                         South Street: EB I-76 exit only. This is a slip ramp to a one-way frontage
                          road. Therefore meeting the local access from/to the reverse direction is
                          indirect. The original design of I-76 had this ramp as part of a split
                          interchange including the Dart Ave. Ramps. The WB entrance ramp was
                          eliminated with the construction of the SR 59 ramps. The Dart Ave. ramps
                          currently function as a the “other half” of the SR 59 interchange and the
                          South St. ramp with relatively low volumes is essentially a independent
                          local interchange.

           On the I-77 SB ramp there is also a partial access (1 / 4 access) to Lovers Lane. Also, all the
           access to Lovers Lane is off the I-77 ramp, the exit is not accessible to SR 8 traffic.

           The SR 59 interchange is a freeway-to-freeway access only for I-76 to/from the west. (The
           SR 59 freeway is to/from the north only). The Dart Ave slip ramps to the South St./Russell
           St. frontage roads do provide, through connections to the SR 59 frontage roads, a measure of
           “complete access” for the SR 59 system. However based on the guidelines the access should
           be direct to SR-59 not the frontage road.

           A global design deficiency affecting the Akron Central Interchange Project Corridor is route
           continuity. Generally the concept applies to the longer distance through traveler and means:

                         Through traffic doesn’t need to change lanes between major interchanges,
                         Movements to lesser classified routes are from/to the outside lanes,
                         Where equal routes overlap and then diverge, left or straight (through)
                          directional movements should be from the inside lanes, right directional
                          movements should be from the outside lanes.
                                                    9 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                             URS
                                                                                                   DRAFT


           Within the Central Interchange (I-76/I-77/SR 8), I-76 enters and exits on both sides on the
           inside lanes; I-77 enters and exits the interchange on the outside lanes. Three miles west, at
           the I-76/I-77 or North Kenmore interchange, I-76 enters and exits on both sides of the
           interchange on the outside lanes while I-77 enters and exits on the inside lanes. Therefore,
           through traffic for both I-76 and I-77 must change lanes on the three-mile segment between
           the North Kenmore and Central Interchanges to accommodate a through move along their
           preferred route. On the south side of the Central Interchange, I-77 the major route is on the
           outside lanes, while the minor route through the interchange, SR 8, uses the inside lanes. (SR
           8 begins [ends] at the south end of the Central Interchange.) Three miles south of the Central
           Interchange, at the I-77/I-277/US 224 Interchange, I-77 SB through traffic can be in all lanes.
           The two lesser/minor routes diverge from both the inside, to US 224, and outside, to I-277,
           off the mainline. (NB the exiting movements are reversed US 224 from the outside, I-277
           from the inside lanes.)

           Route continuity should be viewed from two perspectives, operations and driver perceptions.
           On the West Leg, the estimated 2030 peak hour through traffic on I-76 is approximately
           1,100 vehicles in each direction, I-77 through traffic is estimated at 1,300 vehicles. At the
           Central interchange approximately 400 vehicles on SR 8 could be associated with long
           distance travel from the North Kenmore interchange. Based on traffic splits at North
           Kenmore, the larger proportion of SR 8 vehicles come from I-77. However, the location of
           major destinations relative to the regional alignments of I-76 and I-77 suggests the difference
           is small.

           Approximately half of the traffic entering the West Leg in the peak hour is local, primarily
           from interchanges outside the corridor to interchanges within. This confounds route
           continuity on the West Leg. Based on the relative entering/exiting volumes at the North
           Kenmore, the largest proportion of locally oriented traffic will be from I-77. Thus I-77
           should be on the outside entering the West Leg and on the outside leaving. This minimizes
           the amount of weaving to exit locally. At the Central Interchange, however, traffic splits
           entering the West Leg suggest I-76 should be on the outside relative to I-77. The location of
           major destinations and the regional alignment of SR 8 suggests the local component on the
           east half of the West Leg is minimal.

           On the south side of the Central Interchange, I-77 should be on the inside lanes as the higher
           order route. However, from a volume and operations perspective, the current relative
           locations of I-77 and SR 8 are appropriate. Since SR 8 is a major regional freeway link, the
           SR 8 proportion of “long distance’ travelers on I-77 south of the Central Interchange is larger
           than those from I-77 suggesting it is the ‘major route.” In the future, five lanes will be
           required entering (leaving) the South Leg, three from SR 8 and two from I-77, although
           capacity needs are four lanes and, with local traffic, can be reduced to the existing three
           lanes. Since the design practice is to drop lanes from the outside, merging the smaller
           volume I-77 into the larger (SR 8) favors the current configuration

           Based on anticipated I-76 and I-77 traffic 2030 volumes and operational considerations,
           neither the Central Interchange nor the North Kenmore Interchanges provide good route
                                                   10 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                            URS
                                                                                                    DRAFT

           continuity. Driver perceptions/expectations with respect to sense of direction and
           positioning for longer distance movements are also complex. For the long distance I-77 SB
           traveler approaching the North Kenmore the mainline location is clear, the move toward the
           Kenmore Leg is to another Interstate and therefore an exit. Leaving the North Kenmore, the
           next major change of direction is “to the right.” Therefore, being on the inside lane and
           needing to move to the outside lanes requires a decision to move to the outside. At the
           Central Interchange, the right hand movement of SB I-77 exiting interchange is logical.
           However, the left hand “entrance” of SR 8 on the South Leg of the Central Interchange is
           inconsistent with the concept of a lesser route joining a major route.

           For the long distance EB I-76 traveler approaching the North Kenmore interchange, the ramp
           for I-76 is logical it places the move on the lanes closest to direction of travel. However, the
           exit to a different route is from the “through” inside lane. The entrance to the West Leg on
           the outside, however, requires a decision to move to the left or inside lanes. Approaching the
           Central Interchange the logical move is straight ahead and therefore the through movement
           on the inside is appropriate. However, the left hand exit to SR 8, a lesser route (although a
           freeway), is contrary to driver expectations.

           Northbound and westbound travel is similarly complex. For the I-77 NB traveler, the right
           hand exit of the major route is not logical from the concept of the major route and through
           lane on the inside and making a right hand move to go left. Entering the West Leg outside
           again requires a decision by the I-77 NB traveler to move to the inside lanes. However, from
           the perspective of the longer distance movement being on the outside (as I-77 does bear right
           to the north after the North Kenmore interchange) is relatively logical. For the I-76 WB
           traveler entering the Central Interchange on the inside lanes and exiting on the inside is
           logical based on a straight through movement. Downstream, the existing right movement to
           go left onto the Kenmore Leg is not logical. In the Central Interchange the left movement
           between to different Interstate routes, I-76 WB to I-77 SB, is also contrary to expectations.

           As discussed above, the not all the ramp locations within the Central Interchange meet the
           operational needs to minimize weaving or cater to driver expectations. However, the major
           freeway-to-freeway interchanges relatively short distances to the west and south also have
           route continuity considerations with respect to operations and driver expectations.
           Correcting route continuity is needed to improved operations by minimizing weaving and
           conforming to driver expectations.

           An additional consideration is the physical condition of the roadway including bridges.
           Most of the roadway components are 45-50 years old. The newest facility is the SR 59
           connection completed in 1986. Some structures have had major repairs such as the Grant
           Street and Wolf Ledges bridges in 2005 and 2006. Within the last five years major signs
           have been replaced and the mainline milled and a new wearing layer of asphalt applied.
           Most bridges in the Central Interchange or over/under adjacent local streets were given a
           general assessment of 5 on the most recent bridge inspection and have sufficiency ratings in
           the low to mid 70s. Those bridges with sufficiency ratings over 80 included Brown Street,
           Inman Street (2), LaFollette Street, and the WB I-76 over I-77 WB and SR 8. Most West
           Leg, I-77 and SR 8 bridges were given a general assessment rating of 6 or 7 on the most
                                                   11 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                             URS
                                                                                                 DRAFT

           recent inspection and have a sufficiency rating above 80. Those with low sufficiency ratings
           include the Boulevard (72.0), Princeton Street(74.7), Broadway Street On Ramp to EB I-76
           (67.1), Firestone Boulevard (on I-77, 76.5), Lovers Lane (on I-77, 71.6) and Beacon Street
           (on SR 8, 72.9)




                                                  12 of 12
6/9/2012
698f8c21-9aa0-46a5-8143-7f8398ec1ce5.doc                                                          URS

								
To top