The aerial structure on the west side of SEPTA’s Blue Line was rebuilt starting near the portals at 40th Street and extending to Milburn Station where the at-grade track begins. The project spans approximately two miles and was accomplished while SEPTA continued to operate service on the line. All structures were pre-fabricated and then constructed during a series of planned nine-day shutdowns and weekend shutdowns. Two existing single crossover interlockings were converted to new scissors type double crossover interlockings. All existing cable currently located on a wooden pole line alongside the structure, was newly installed in the guideway trough system.
During the course of construction, the signal system was temporarily disabled many times to allow construction to progress and then returned to service for revenue operations. Furthermore, two interlockings were significantly modified as described above. HMM provided engineering services to support to the contractor in these efforts as follows: