Hi Steve, you've dug up another interesting one.
Quote:
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Originally Posted by the NTSB report
Chessie instructions specify that for trains operating with active PTC, crews performing pickups, set offs, or other switching activities including shoving movements must use restricted mode for the PTC system. In restricted mode, the PTC system allows train movement at restricted speed and no longer automatically stops the train before it can violate a red (stop) signal.
AND
Preliminary event recorder data indicated the train speed never exceeded 20 mph (upper limit threshold of CSX restricted speed rule).
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So there's a significant chink in the PTC armour.
Mind you, most safety systems have to be overriden at some point. Our own TPWS has to be isolated when performing Temporary Block Working (ie, passing 2 or more signals at Danger). The Rulebook states that when you stop after completing the movement you MUST reinstate it. But if you forget, you can
run around all day without it until you shut the desk down (take your key off). TPWS will then become active the next time the desk is started up.
I've heard of at least one SPAD over here where a guy failed to put the TPWS back in.
I suppose they could put in a device that automatically reinstates it above 50mph (the maximum speed allowed for wrong direction working during Single Line Working), but then some trains never get above 50 all day.
Or cheaper still, a little voice announcement every so often saying that TPWS is isolated - although that might drive you up the wall after a few hours!
As I tell my boss on a regular basis, whenever humans are involved somebody will screw it up sooner or later.
"There, but for the grace of God, go all of us"........
Cheers, BW