SEPTA
Market-Frankford Subway-Elevated (MFSE) Resignaling

RAILSIM had a leading role in SEPTA's work to implement the new automatic train control (ATC) signal system that went into service on its busiest rail line, the Market Frankford Subway-Elevated in September 2004.

Back in 1992, RAILSIM was used to determine the optimal performance characteristics of the new Adtranz M-4 vehicles that were purchased to improve overall service and reliability, including audio frequency cab signals and bi-directional operation.  That study led to the planning stages of the resignaling effort.

At that time, this 14-mile double track line ran at peak load with an obsolete signal system consisting of wayside signals in one direction only with mechanical trip stops.

RAILSIM was also instrumental to the subsequent design phases for the ATC resignaling effort, performing extensive simulations of various headways, running speeds and consists to determine the optimum minimum run time and headways. The RAILSIM Network Simulator analyses included both six- and eight-car trains.

Finally, RAILSIM developed the signal block layout and signal control lines, optimizing the capacity and trip times of the train control design while minimizing the number of ATC bond locations and the capital cost of the new system.  RAILSIM determined that SEPTA could realize an improvement in throughput from the former system's 26 trains per hour, to 37 trains per hour under the new control system, with improved minimum headways on both tracks.  The new ATC system is capable of sustaining 97-second headways (based on a 30 mph speed command), while the former system could sustain only 130-second headways (based on a 25mph operating speed).

The new state-of-the-art ATC system, completed and put into service in 2004, enables central control of all interlockings, track switches, and train movements.  It consists of coded track circuits, with wayside signals only at interlockings.  It provides train overspeed protection with automatic braking, and bi-directional train movements with full signaling.  Conventional trip stops at key points protect switches and increase throughput and headway. Interlocking track circuits are power frequency dual element vane type with audio frequency cab signals overlaid. All interlockings use vital microprocessor-based control systems. Wayside signals are used at interlockings only.