Positive Train Control Interface Design Issue With Locomotive and Cab Car Braking Systems

Issuing agencies

Abstract

FRA is issuing Safety Advisory 2021-01 to make the rail industry, including railroads and railroad employees, aware of a recently identified interface design issue relating to how positive train control (PTC) systems in use throughout the United States interface with locomotive and cab car braking systems. This recently identified interface design issue allows a train crewmember to circumvent a PTC enforcement by manually cutting out the pilot valve/ brake stand, commonly known as the cut-out valve, prior to the PTC system initiating the brakes. This interface design issue poses a significant safety risk by allowing a PTC system to be disabled and unable to initiate the brakes to prevent a train-to-train collision, over-speed derailment, incursion into an established work zones, or the movement of a train through a switch left in the wrong position. This Safety Advisory recommends that all railroads operating with PTC systems immediately remind crewmembers that circumventing a PTC enforcement is subject to civil penalty or disqualification for the locomotive engineer or conductor responsible; audit the designs of PTC systems as implemented on all types of locomotives and cab cars; assess the extent to which the design of the system could allow a locomotive or cab car's PTC system to be circumvented by a crewmember; develop and implement a plan to mitigate and/or correct this design issue; and provide FRA with a schedule for completion of the identified actions.