Designing Access Improvements on I-95 in Philadelphia

Running parallel to the Delaware River along Philadel­phia’s eastern border, Interstate 95 (I-95) is an important thor­ough­fare for commuters, freight traffic and visitors to the city. It provides north-south access for 158,000 daily vehicles traveling to and from the city’s north­east­ern neigh­bor­hoods and suburbs, Center City, the South Philadel­phia Sports Complex and Philadel­phia Inter­na­tional Airport, and it connects Philadel­phia to New Jersey via multiple bridge crossings. For more than a decade, the Penn­syl­va­nia Department of Trans­porta­tion’s (PennDOT) District 6 has been leading a long-term, multi-phase initiative called I-95 Revive to improve and rebuild the interstate, its ramps, inter­changes and bridges.

The Section BSR project entails widening that 2-mile stretch from three to four lanes in each direction to add capacity, alleviate traffic and improve mobility and safety. It also involves rebuilding all the bridges on this segment. In addition, one of the directives from the Federal Highway Admin­is­tra­tion was to consolidate partial inter­changes and ramps into full inter­changes and to prevent interstate traffic from out-letting onto local streets and communities. CDM Smith, therefore, performed a compre­hen­sive study of the area along with PennDOT and city officials, resulting in a recent addition that extends a city street 1.5 miles to the new interchange to improve access to I-95 and to help divert truck traffic around the local communities rather than through them.

CDM Smith has been involved on Section BSR since its most early phases, when we completed a point of access study of the combined Bridge Street interchange and the Betsy Ross Bridge segments. CDM Smith’s team has since completed preliminary engineering and is currently working on the section’s final design. The existing highway has been in place for 50 years, and it is likely that the recon­struc­tion will be in place for at least that long, so it is critical that we get the design right. A carefully composed design will not only have a positive effect on regional mobility but also local safety and quality of life.

Unlike a typical highway or bridge project, Section BSR incorporates a number of additional design components, including multi-use trails, pedestrian lighting, parking areas, “green streets” facilities and stormwater management. Additionally, the section’s new design will re-align or relocate many local streets to ensure efficient connectivity to the improved interstate interchanges. To get the design right, the CDM Smith team has been actively involved in the community, gathering feedback and support from local stakeholders. The firm’s outreach activities have ranged from small meetings with residential and business organizations in each affected neighborhood to large town-hall style public meetings. The input gathered from these interactions is incorporated into the project continuously throughout our design process.

The final design of the section includes reconstruction of seven mainline dual structures, including a 1,000-foot fracture-critical curved steel viaduct and a 345-foot curved ramp structure. These structures will include a combination of post-tensioned concrete pier caps and redundant steel cross-girder systems that will straddle city roadways and major utilities. Another important aspect of the section’s final design is eliminating existing lane drops at the Bridge Street interchange to solve a major traffic problem that has plagued the area for years. The reconfiguration of interchange ramps, as well as the upgrading of drainage structures, lighting, signage and retaining walls, is another important piece of the section’s revival, which is forecasted for completion in 2022.