In the Heart of the City
January 10, 2023
For over 40 years, a pedestrian bridge in Philadelphia’s health care epicenter connected the Perelman Center for Advanced Medicine (PCAM) to the Hospital of the University of Pennsylvania (HUP). Extending over 33rd Street and 34th Street, the bridge was built in the 1970s, followed by a temporary addition that extended over Convention Boulevard in 2015. But just like the health care industry, the construction industry is ever evolving, and when new buildings and walkways were added to the campus, the pedestrian bridge that once allowed thousands to get from one building to the other became obsolete.
Soon after Penn Medicine opened its Penn First Hospital, which included the addition of three new pedestrian bridges and an underground tunnel that connected the Penn Medicine properties together, NDA member Geppert Bros. Inc. began work on removing the old bridge.
Bringing a local level of proficiency and comfortability to demolition work performed in the Philadelphia region, the L.F. Driscoll/Balfour Beatty Construction joint venture (JV) contracted with Geppert Bros. Inc. to determine the best demolition plan of action.
“Thackray Crane provided the team with possible crane locations and capacities,” says Pasquale Marconi, Geppert Bros. vice president. “From there, we worked with structural engineer Wing Au and E&K Scaffolding to determine locations where the bridge would be separated and how.”
Additionally, Geppert Bros. superintendents and the project management team worked with their subcontractors to determine the best way to remove the bridge under the restrictions set forth by the medical campus’s property managers.
“Throughout the entire process, it was made known that we were guests in the area,” Marconi says. “Other than nightly lane closures and weekend street/sidewalk closures, one of the goals of the project was to minimize the impact to the surrounding health care community, which included cleaning up and readying surrounding areas for both pedestrian and vehicular traffic.”
After several months of extensive planning and meetings, it was determined that the bridge would be removed in seven separate sections over the course of two long weekends. In December 2021, demolition work began. To reduce the weight of the bridge sections, Geppert Bros. removed all the architectural components. Anything that didn’t contribute to their stability was removed. Interior fit-out, exterior curtain wall, roof structure and floor structure were all removed, leaving only the structural steel skeleton.
“The first weekend consisted of picking and removing the three bridge sections that crossed over Convention Boulevard,” says Adam Budin, Geppert Bros. project manager. “The featured pick of the first weekend was the longest (90 feet in length) and heaviest (63,000 pounds) section that was partially tucked under the PCAM building with about 1 foot of clearance between the top of the bridge steel and the PCAM building structure. This section was being picked past its original design splice, and our engineer designed and Geppert fabricated stiffeners to be attached to the splice to keep the section from buckling when picked. The center of gravity was determined, and the pick points were all verified by our engineer. Once freed up, the section remained 100% level and did not touch the PCAM overhang.”
On the second weekend, the remaining four bridge sections were picked and removed. These sections were lighter, as they were from the original HUP bridge, they were only 10 feet away from the new connector bridge that had been constructed to take its place. After the removal of the bridge was complete, the crew had to remove the five concrete support piers that held up the bridge’s two structures.
“Because of the construction and location of the piers, it was determined that the piers would need to be saw-cut to be removed in lieu of using large hydraulic hammers that would cause both extensive noise and vibration,” Budin says. “The piers were large concrete structures, and due to the sheer size of them, they needed to be cut into sections and rigged with a crane into a truck for removal. Each cut and pick needed to be planned with both the crane capacity and truck capacity in mind.”
Working exclusively at night during February and March, Geppert’s subcontractor, Chesco Coring & Cutting Inc., provided over 45 wire cuts, and Thackray Crane performed 50 crane picks so that the piers could be safely removed. Overall, 500 tons of concrete piers were saw-cut, picked and taken off-site.
After four months, Geppert Bros. wrapped up demolition in March 2022. The job was considered a great success, with the work completed on schedule, within budget, with zero loss time accidents and minimal disruptions to the surrounding health care institutional neighborhood.