Chestnut Street & Market Street Bridges

Pennsylvania Department of Transportation | Philadelphia, PA
downtown bridges

Benesch was retained to inspect, assess and rehabilitate or replace the structures on Market and Chestnut Streets. This challenging assignment required balancing the needs and desires of PennDOT, the City of Philadelphia, local businesses, three railroads (Amtrak, SEPTA, & CSX), multiple public & private agencies, universities, vehicular/bicycle/pedestrian commuters, and the local residents with respect to traffic, schedule and budget, all while extending the remaining useful life of the structures by at least 30 years.

The existing bridges on Market Street were originally constructed to connect the 30th Street Station Complex to Center City Philadelphia in the early 1930s. The historic multi-span open spandrel arch with masonry facade is listed on the National Register and was built integral with the SEPTA Subway Tunnel below the Schuylkill River. The river crossing along with the four-span steel structure over the Schuylkill River Trail, CSX railroad and abandoned railroad spans provide a vital multi-modal transportation link for the area. The existing Chestnut Street structures encompassed the elevated platforms around the historic 30th Street Post Office Building and the bridge network extending east on Chestnut Street over the Schuylkill River to 24th Street.

Because the project area has undergone a significant urban renaissance—including a 2.7M-square-foot tower poised as the city’s first “vertical neighborhood” and other nearby commercial structure renovations—extensive stakeholder coordination and construction staging were key to the project’s successful design.

The presence of three nearby railroads (SEPTA, CSX, and Amtrak—the latter including its third busiest rail hub in the nation, Philadelphia’s 30th Street Station) and several 100+-year-old structures presented additional challenges. Many of these structures are considered contributing elements to a National Register-listed historic district.

Practice Areas


  • 2023, Grand Jury Award, Preservation Alliance for Greater Philadelphia
  • 2023, Special Focus Award - Ralph Modjeski Award for Excellence in Transportation Design, Preservation and Archaeology, Preservation Pennsylvania
  • 2022, Project of the Year (over $20 Million), American Society of Highway Engineers - Delaware Valley, PA


view of the Market Street bridge from an adjoining roadway
View of the Market Street Bridge project showing traffic on the bridge crossing the river

Structural improvements included plate repairs and replacement of steel members, painting steel superstructures, new railroad protective fence and restoration of ornate metal railings, masonry cleaning and repointing and internal strengthening of an arch structure over the CSX tracks. Accelerated Bridge Techniques were implemented for staged construction of bridge decks, roadway and sidewalks.

The overall design also included several streetscaping elements at the request of the City of Philadelphia: narrower roadway with widened sidewalks and improved trail access; buffered left side bike lane; refurbished ornate lighting; replaced navigation lighting; new pedestrian level lighting; and replacement bridge barriers and replica historic railings.


Market Street Bridge in Pittsburgh, PA

Maximizing Project Value

While the project’s budget seemed to only allow for rehabilitation improvements which would increase the remaining service life of the Market Street structure another 30 years, Benesch developed a best value solution for the same estimated construction cost, thanks to the results of a value engineering study.

Our team developed a plan to replace the multi-span bridge with a single-span bridge, rather than rehabilitate it, using innovative span elimination techniques for two abandoned railroad spans, a reinforced concrete transfer beam on concrete caissons to span over existing subway tunnels below, and by retrofit of a portion of the existing adjacent river bridge common substructure to accommodate the bridge replacement superstructure.

Not only did this design solution align with the cost of the original rehabilitation plans, but it added long-term sustainability and aesthetic appeal to a structure that holds significant historic and functional value within the community. The replacement extended the life of the bridge from 30 years to 100.