Coordinated Efforts to Sustain Stray Current Mitigation on an Aging Heavy-Rail DC Transit System

Modern heavy-rail DC transit systems are designed to control stray DC current interference at the source.  The primary design feature that achieves this goal is the utilization of an ungrounded traction power distribution system.  The traction power distribution system consists of a contact rail component that delivers DC current to the train motors and the running rails that act as a return path for the DC current to the traction power substation.   Both the contact rail system and running rail systems are constructed utilizing methods and materials to achieve a level of electrical isolation from earth/ground that mitigates DC current leakage from the traction power system.

Sustaining the effectiveness of stray current mitigation as a transit system ages requires a coordinated effort that involves the transit agency and operators of neighboring structures.  This paper discusses some of the elements of the coordinated effort that may aid the transit agency and neighboring operators in monitoring and sustaining stray current mitigation.