Not sure how the signaling system detects a train's or a car's exact location, but I can see the last car on the siding not being pulled far enough onto the siding so that it allows clearance on the main.
Publius Plunkett wrote:It's a "controlled" interlocking, with signals. From what it appears, the "foul mark" in the Siding what would allow an eastbound signal be displayed on the Main, was too far east...the wheels passed the mark and "shunted the signal"... but the body of the Engine didn't. The "shunting" indicated that the train was in the clear, but it fact it wasn't. That's not the fault of the crews of either train. The Railroad will correct the issue and it most likely will never happen again.It’s not the “foul mark” that was too far east, it’s the location of the eastbound interlocking signal on the north track and its associated insulated joint that demarcates the signal circuit limits that are too far east. If the signal were located correctly then no part of the train could have been fouling the main track and still allowing a clear signal on the main track. If the signal and the associated track circuit are indeed too far east and they permit a train to foul the main while still permitting a clear signal for a conflicting move, then that is a signal design failure. I’m not an expert in signal system design but that’s one piece of the design that is a no-brainer, and the no-brain designer...and all of the people who signed off on the no-brain design...should be held accountable for what could have been a fatal error. Multiple failures of process at multiple stages of the signalization project had to have occured for this to have been built and commissioned, if indeed it is determined that this was the cause of the collision. Were I in a position of responsibility in either the Signal Department or the Transportation Department, I would be immediately ordering a review of the entire Montauk Branch East End signal system design to ensure that no other design flaws exist.