The Washington D.C. Metro utilizes an Automatic Train Control (ATC) system designed in the mid 1970’s. This ATC system employs passive track bed markers and antennas inductively coupled to the track to send and receive audio frequency control signals over the rails. The ATC system is only installed in revenue passenger cars and has never been installed on any other vehicle. Recently, a new inspection vehicle was delivered that includes an inspection module that interfaces with this train control system to inspect the control and track occupancy signals.
This paper will discuss the challenges of designing a track circuit inspection system and retrofitting a refurbished ATC system designed for a revenue vehicle to a custom self propelled inspection car to ensure uniform inductive coupling over curved track, maintaining dynamic clearance envelop of the inspection car and design of custom broadband signal antennas to prevent interference. Additionally this paper will discuss the technical approach for conducting the inspection and results achieved during testing.