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Project Highlight:
Southeastern Pennsylvania Transportation Authority (SEPTA) Crum Creek Viaduct Bridge Replacement
The project involved the investigation of the existing foundation conditions of the SEPTA Crum Creek Viaduct for the potential rehabilitation or replacement of the 900-foot railroad bridge over Crum Creek and the 220-acre Crum Woods that carries trains on the SEPTA Media/Elwyn regional rail line between Swarthmore and points west. The viaduct was built in the 1890s and acquired by SEPTA in the early 1980s. In 1983, SEPTA completed a renovation project to extend the working life of the viaduct by 25 years. Service to the Media/Elwyn Line was to be suspended if SEPTA did not receive the necessary funds to replace the viaduct. A.G.E.S., Inc. provided preliminary geotechnical design for the bridge replacement which was procured as the first large design-build project for SEPTA. The allowable foundation types included micropiles and drilled shaft foundations socketed into bedrock.
During construction, A.G.E.S., Inc. provided review services as the owner’s representative. The review included updated design procedures for drilled shaft foundations utilizing the recently revised AASHTO LRFD design manual to account for a combination of both side friction and end bearing in bedrock. Careful consideration was made to minimize impacts to the existing bridge foundations, which were to stay in-service during most of the substructure construction to reduce service outages on the rail line. Slope instrumentation was installed by the contractor based on requirements in the project specifications to ensure that the overall stability of the existing slopes and foundations were not compromised during construction activities.