Most people traveling along Broad Street between Callowhill and Noble Streets probably don’t realize that they’re actually on a bridge over the City Branch. Originally constructed in 1889 when the City Branch was in the final stages of being submerged below street level, the original bridge superstructure was replaced in 1956, the bridge deck repaired in 1983, and now the bridge is again nearing the end of the road, so to speak. In the coming years, the structural integrity of the bridge will have to be addressed to ensure the safety of the 21,000 motorists and continuous stream of pedestrians who pass over the bridge every day.

Because Broad Street is a state road, PennDOT oversees its maintenance. At the beginning of 2012, PennDOT began the process of evaluating a number of alternatives for the City Branch Broad Street bridge replacement and reaching out to stakeholders, including Friends of the Rail Park and Callowhill Neighborhood Association, to determine whether there were any preferences among those alternatives.

The steel bridge is comprised of five spans, or horizontal segments divided by vertical supports. The City Branch runs beneath the northern two spans and is confined by the north masonry abutment wall and an internal masonry pier to the south, both of which are part of the original 1898 construction.

PennDOT’s consultant team considered three scenarios in replacing or repairing the bridge structure. One scenario involved simply rehabilitating, reinforcing, and replacing structural elements as needed, but keeping the structure essentially the same as it is today. Another option was to fill in underneath the bridge’s three southern spans, which currently exist as an open void between the subgrade level of the Inquirer Building on the west side of Broad to that of the Terminal Commerce building on the east side of Broad. The third and low-cost alternative would have been to simply fill in all five spans including the City Branch right of way, effectively making the bridge a road, and, in the process, creating a significant “road block” to the vision for a continuous three-mile linear park and recreation path along the former rail lines.

Looking east underneath the Broad Street Bridge over the City Branch, here being used as a surface parking lot. Inset shows the view of the stunning art deco Lasher Building, which reveals itself as you emerge from under the east side of the bridge.

This potential threat to the Rail Park was a major contributing factor in our decision to pursue a conceptual design for a half-mile stretch of the City Branch including its intersection with Broad Street. Friends of the Rail Park’s conceptual design process through the Community Design Collaborative ran parallel to PennDOT’s exploration of bridge rehabilitation alternatives, with both processes coming to a close in early 2013. We were very fortunate to have Joe Sullivan, Senior Associate at the engineering firm Ammann and Whitney and Project Manager/Engineer for the PennDOT Broad Street bridge project, participate in the conceptual design process as a member of the Community Task Force and provide two-way communication between the two projects as they evolved.

A number of factors went into PennDOT’s decision, and having a plan in place that depended on preserving circulation underneath Broad Street was one of them. Friends of the Rail Park was very relieved to receive official word from the Broad Street bridge project consultant team on July 1st that the City Branch would not be filled in under Braod Street—all five spans would remain open. Along with replacing or rehabilitating other elements of the structure, a line of steel columns and cross-bracing bisecting the City Branch under Broad will be replaced with concrete piers—the only change anticipated that will impact the character of the City Branch under the bridge.

Funds have not yet been allocated to final design for the bridge replacement project, though PennDOT is hopeful that the final design process will be underway this year. PennDOT estimates that the earliest construction could commence would be in 2015.

Read more at Plan Philly.