The accelerated bridge design-build project involved replacing a 121-year-old railroad viaduct bridge over Crum Creek in the Philadelphia suburbs. The $55.5-million new bridge was designed and delivered on time and under budget despite an accelerated 19-month schedule.

The 735-ft-long, steel girder bridge has five spans, with a maximum span length of 157 ft. The bridge also has a monitoring system that was installed on the existing structure to detect movements and the stability of the steep slopes during construction.

The team was only permitted an 11-week rail shutdown of the existing bridge. During that shutdown period, crews worked around the clock to demolish the bridge, erect the new superstructure and deck, and perform rail and catenary electric transmission work and install the signal system. The new bridge was placed using the lateral slide accelerated bridge construction technique.

Girders for the new bridge were assembled on one side of the existing bridge, including the precast deck. The new girders were supported by new straddle bents built under the existing bridge, which remained fully operational during that period of construction.

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