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Public-Private Partnership Success
Ship Road and Swedesford Road Intersection Improvement Project
By Robert G. Prophet, P.E.
Project Manager, Highway Design
Traffic Planning and Design, Inc. (TPD)

In October 1998, Traffic Planning and Design, Inc. (TPD) began design work on the Ship Road and Swedesford Road Intersection Improvement Project in West Whiteland Township, Chester County, PA. After construction was completed in April 2001, TPD and West Whiteland Township won "2nd Runner Up" in the Pennsylvania State Association of Township Supervisors (PSATS) 20th Annual Road and Bridge Safety Improvement Award program, judged by a panel comprised of representatives from PHIA, PennDOT, and PSATS. The "job well done" included structural design, traffic signal design, intersection improvements, and highway widening and realignments which "resulted in well-documented safety improvements." This project also received Honorable Mention from the Delaware Valley Section of the American Society of Highway Engineers (ASHE) for 2001 Project of the Year Award.

As described below, this project involved close coordination with multiple stakeholders and regulatory agencies, and required quick turnaround due to other construction projects scheduled in the surrounding area. Other firms contributing to this project's success included Pennoni Associates, Inc. who completed the original traffic study which included alignment alternatives and Eastern States Engineering who completed the survey and site work for the adjacent Swedesford Chase development being constructed by Toll Brothers, Inc.

Project Description
The intersection of Ship Road (State Road 1001) and Swedesford Road (Township Road 413) is located in West Whiteland Township, Chester County, PA approximately ½ mile northeast of the Exton Square Mall. Both Ship Road and Swedesford Road are used as bypass routes for motorists trying to avoid traffic delays and traffic signals on PA Route 100 (1/2 mile west of the intersection) and Business Route 30 (1/2 mile south of the intersection) both of which are classified as Principal Arterial roadways. This junction was originally designed as two "T" intersections, offset by approximately 275 feet, with a tributary to Valley Creek located between the two intersections. This type of design was commonly used in the early part of the 20th century to avoid multiple stream crossings by both of the intersecting roadways. This offset required vehicles traveling along Ship Road to make two turning movements, therefore, increasing commuter delay and the possibility of crashes. Concerns with the existing intersection were magnified due to the large volume of vehicles performing this movement and the consistent flow of traffic on Swedesford Road, which did not allow for proper gaps in traffic.

A traffic study, which analyzed various design alternatives for the intersection, was developed in late 1997 by Pennoni. The focus of the study was to increase the safety and mobility at the intersection of Ship Road and Swedesford Road. Based on the study, the selected intersection improvement alternative included signalizing the intersection, realigning the western and southern legs of the intersection to create a single skewed four-way intersection, and the addition of left turn lanes on each approach. In October 1998, Toll Brothers, Inc. and West Whiteland Township employed Traffic Planning and Design, the Township Traffic Engineer, to develop plans for the intersection redesign. The plans were required to be prepared and submitted to PennDOT as a Highway Occupancy Permit (HOP) application with West Whiteland Township as the permit applicant.

Design of the intersection was complicated by several factors within the project limits including the Tributary to the Valley Creek, the proximity of a Township and County Park on the northeast and southeast corners of the intersection, historic structures on the northeast and northwest corners, and the presence of wetlands on the northeast corner. An existing 3'x 6½' reinforced box culvert carried the Valley Creek tributary beneath the offset leg between the two T-intersections. Originally, it was expected that this existing box culvert would be able to be extended as required or replaced with an elliptical pipe. However, preliminary coordination with DEP eliminated this possibility. Following this coordination, further research of the flood history within the area indicated that the existing culvert had potential flooding concerns. These concerns, along with the anticipated extensive intersection improvements, dictated that the existing box culvert be replaced. During the design process and the flood history research, concerns also arose about flooding, which was occurring in a residential area located downstream of the intersection. This flooding occurred along the tributary to the Valley Creek during higher intensity storm events. Therefore, any design of a replacement box culvert carrying the creek through the redesigned intersection needed to be developed in such a manner as to minimize impact on downstream property owners.

Based on TPD's in-depth hydraulic analyses, the replacement structure required for this project was 5½' x 14' reinforced box culvert with a total required length of 206 feet. The extensive culvert length was required because the Valley Creek tributary flowed directly through the center of the proposed intersection. Any attempts to relocate the intersection were prohibited by the adjacent park and the adjacent historic structures, while any attempt to minimize the culvert length required significant stream relocation. Therefore, the location of the creek was not altered as part of this project and the culvert was designed and constructed at the 206' length. Since the total length of the box culvert exceeded 100 feet, it was sized to handle a 100-year design storm. TPD coordinated with the Army Corp of Engineers, Department of Environmental Protection, Chester County Conservation District, and Trout Unlimited throughout the development of the design of the box culvert.

Due to a scheduled structure replacement on PA Route 100, approximately ½ mile west of the intersection, West Whiteland Township imposed extensive construction deadlines, since this intersection would provide alternative traffic routes for commuters affected by the elimination of one lane in each direction on PA Route 100. Due to this intense schedule, TPD, West Whiteland Township, and PennDOT coordinated closely to achieve the required deadlines. As a result of the tight schedule and late addition of structural design tasks, a final structural plan package included a combination of geometry, plans; and details developed by TPD, along with specific precast culvert and precast wingwall shop drawings provided by Rotondo Precast. This modified submission format, which required extensive coordination between TPD, the Township, PennDOT, Rotondo, and the contractor, resulted in the successful fabrication and installation of the replacement culvert within the required time constraints. A typical PennDOT submission procedure would have extended the fabrication and construction schedule by a minimum of three months.

Another element, which increased the complexity of the design and coordination of the intersection realignment, was the presence of eight (8) utility companies. There were five (5) existing above-ground and underground utility lines, which were going to be affected and, therefore, required relocation as part of this project. An additional three (3) utility companies requested that their lines be relocated/extended through the intersection while it was under construction. Of particular concern was a high-pressure Sun Oil pipeline running parallel to Swedesford Road immediately south of the intersection. As part of this project, the proposed box culvert was to be extended to the south of the existing intersection immediately above the pipeline. Therefore, a decision was made to relocate the high-pressure line approximately 50 feet to the south to avoid any conflict with the box culvert. Closure of the gas line required extensive coordination with Sun Oil, West Whiteland Township and an adjacent construction site located 1 mile east of the intersection of Ship Road and Swedesford Road.

One final design element, which required special attention of the utility companies and contractors, was the proximity of two 100-year old trees on the northeast corner of the intersection. West Whiteland Township officials requested that the trees remain undisturbed during construction. Therefore, special measures were taken when designing the curb line and utility relocations as to not disturb the trees. To ensure that the trees would survive construction, an arborist was hired by the Township to trim certain portions of the trees where root damage could have occurred.

Contract and Scheduling
Construction of the intersection improvements was performed by Allan Myers, Inc. and managed by Toll Brothers, Inc., who funded the improvements as part of their adjacent Swedesford Chase land development. Construction was performed under a full detour condition to accelerate completion and to allow for improved safety during installation of the box culvert. Both the Township and PennDOT deemed completion of the intersection improvements critical due to the upcoming reconstruction of PA Route 100 through the Exton Mall area. PA Route 100 was scheduled to be reduced from four lanes to two lanes in order to complete the widening of a major structure. Traffic from PA Route 100 was to be partially diverted onto Ship Road during that period. Due to the efforts of West Whiteland Township, PennDOT, Toll Brothers, Allan Myers, Rotondo, and TPD, the intersection improvements were completed and the road was opened in time for the PA Route 100 lane closures. The following is a summary of the key events:

Commence Intersection Design November 1999
Commence Structural Design March 2000
Intersection Design Approved April 2000
TS&L Submission April 2000
TS&L Approval May 2000
Construction Started May 2000
Final Structure Plan Submission July 2000
Fabrication of Box Culvert Started July 2000
Final Structure Plan Approval August 2000
Utility Poles Relocated August 2000
Construction Substantially Completed September 2000
Roadway Open to Traffic September 2000
Final Paving and Pavement Marking April 2001
(Construction completed)

Significant Techniques or Innovations

The design and construction of the improvements at Ship Road and Swedesford Road involved extensive public-private partnership. Through this partnership, the design and construction of the intersection improvements were completed within a seventeen (17) month time period. This time period is significantly less than the typical four-year time period for design and construction of a similar size publicly funded project.

Coordination was critical to the successful completion of design and construction of the intersection improvements. This involved multiple meetings with utility companies, Township officials, PennDOT, Toll Brothers, Inc. and TPD. In addition, engineers from TPD met with Rotondo Precast, the box culvert fabricator, to discuss and coordinate design issues, shop drawings, and final structure approval. This intensive coordination culminated in a final structure submission to PennDOT, which included drawings and details provided by TPD and shop drawings prepared by Rotondo Precast. This process expedited the approval and construction schedule by approximately three months.

An additional method used by the designers and contractors to accelerate the project was employing a full detour in which all four approaches to the intersection were closed to traffic. This method allowed for the reconstruction of Ship Road and Swedesford Road and the continuous installation of the 26 segments of the box culvert. The detour allowed for extended work hours and provided staging areas for vehicles and equipment necessary for the installation of the box culvert.

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