Abstract: A system for detecting objects in the path of a power operated, movable door operating in a mass transit vehicle, which would obstruct door closing. The system also includes an integral method for detection of a "free wheeling" door occasioned by failure of the door mechanical drive. Method and apparatus disclosed utilize door handle locating devices such as electrical switches located at predetermined points along the door closure track. A combination of door locations along the closure track centrally define positions signaling either door linkage failure with attendant "free wheeling" door, and/or door obstruction, in each case, the system disclosed prevents train motion until the improper door condition is remedied. The combination provides a reduction in passenger hazards occasioned by train movement with defective operator linkage and/or door obstruction due to trapped passengers or other impediments to door closure.