Market Street Elevated Reconstruction Project

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:

• Prepared and obtained approval of a complete test program plan for the signal system work.
• Prepared and obtained approval of detailed installation drawings for the signal system.
• Prepared and obtained approval of work plans for staging and cutover sequencing.
• Design changes associated with interlocking changes from a single to double crossover.
• Oversaw installation of the signal system.
• Performed operational and safety testing of the signal system throughout the term of the contract.
• Final documentation including as-installed drawings and software.