If a runaway train gets on a track signaled for operation in the opposite direction to its direction of motion, will the mechanical trips which are presumably facing the other way work at all?
NTSB report, page 6:
The train passed five train stop mechanisms (or automatic trip stops) between Forest Park interlocking and Harlem-Congress Station. Physical strike marks, signal data logs, and video recorders verified the train stop mechanisms were in the raised position as the unoccupied cars passed. As the five train-stop mechanisms were engaged by the cars, a penalty brake application was initiated. The cars came to a stop, which was the first requirement to recover after a penalty brake application. The cars were initially left unattended in the Forest Park yard with the master lever in the B3 braking position. This was the second condition that needed to be met before a train could recover from a penalty brake application.
Following every penalty brake application, the unoccupied cars came to a stop, but they recovered and continued to move until they struck the stopped train at the Harlem-Congress station.