15th Street Bridge Improvement Project

Modjeski and Masters (M&M) provided engineering services for the 15th Street Bridge Improvement Project as part of a City of Philadelphia On-Call Transportation Engineering Design Services (TED) contract. This included performing a bridge survey, supplemental inspection, coordinating with local stakeholders and adjacent property owners, developing contract documents for bridge and roadway repairs, and performing construction support services.

The 15th Street Bridge Improvement Project was nestled inside several other larger improvement projects, which included the Callowhill Street safety improvements and the Philadelphia Police Department’s full renovation on the former Philadelphia Inquirer building. The Philadelphia Police Department building is bound by, and abuts to, the east fascia line of the 15th Street Bridge.

The existing bridge was in poor condition due to the state of the deck, superstructure, and substructure, and was load posted for 3-tons. The load posting prevented trucks from crossing span 6 (the northern-most span) which exhibited beam failures at the north abutment and were being supplemented by temporary support columns. 

M&M expedited an in-depth inspection of the substructure, superstructure, and concrete bridge deck. Inspectors found extensive deterioration due to leaking deck joints at the abutment backwalls, bridge seats, pier caps, beam ends, and bearings. The project team quantified and located deficiencies so they could clearly develop structure plan details. In addition, the team measured section loss and developed as-inspected live load ratings.

The rehabilitation was designed to minimize maintenance by eliminating all deck joints, using link slabs over bridge piers, utilizing sealed deck joints at the abutments, replacing steel sliding plate bearings with elastomeric bearings, and cleaning and painting the superstructure. The design also included reconstructing the abutments and replacing a steel and reinforced concrete pier caps.

Because the project was only one part of a larger improvement project, effective scheduling coordination was
imperative. The successful and timely completion of this  bridge rehabilitation project was essential to completing the larger Philadelphia Police Department renovation.

M&M was a good steward of the city’s funding by providing right sized solutions the first time. This was a schedule-driven project and many project details were decided late into final design. M&M carefully balanced the timing of design work until decisions were final, while still advancing the design with no rework and meeting the demanding schedule.