PTC passes first test

On Thursday August 27th, 2015 Positive Train Control passed its first real test. At Bovina, TX on the BNSF Hereford Subdivision(part of the Transcon), a cut of cars rolled away from a Grain Elevator, jumped the derail and forced the siding switch leaving the cars derailed on Main 1. A BNSF was approaching on Main 1 and received a PTC command for an immediate stop which was initiated by the PTC controller onboard the lead locomotive which brought the train to a safe stop 2400ft. short of the first derailed car.

What was detected? Was this all within the same signalling block? So basically what I'm asking is, something forced open the switch, which was detected by the system, and the train already within the block was notified to stop? This in the past would not be possible if the train was already in the block, right?

Right, except in cab-signal territory, in which case the cab signal would have dropped. If there was an intervening wayside signal between the train and the obstruction, regular automatic block would have thrown the signal to stop. The remaining problem, yet to be solved (and I don't know how), would be if the cars ran away just as the train approached--there would have been no time to stop.

So in traditional cab signalling, if the train was already in the block, and a switch got rammed open within that block, that would be signalled to the cab?

MCL1981 wrote:So in traditional cab signalling, if the train was already in the block, and a switch got rammed open within that block, that would be signalled to the cab?

If the territory and the locomotive were equipped with Cab Signals the indication within the Cab would drop to Restricting and after a few seconds a horn or whistle would blow. Basic Cab Signals have no ability to enforce speed limits. If the Engineer ignored the Restricting indication then the equipment would initiate a Penalty Brake application and bring the train to a stop. If the Engineer acknowledged the Restricting Indication by moving a lever, then he could proceed at any speed he chose.

That was my understanding of traditional cab signalling as well. So this incident really isn't a PTC victory then, is it? The old cab signalling system would have signaled the engineer to stop. And if the engineer was asleep, it would have stopped itself. The train would have come to a safe stop in either case. The only way this would be a PTC save is if the engineer was intentionally ignoring and overriding the restricting signal, which doesn't seem to be the case. I'm not sure I would call this a PTC victory. It's really just a different system that did the same thing the old system did.

I'm not saying PTC is useless or a bad thing. Just that this is probably not a shining example of it doing it's thing. Cab signalling has been doing what PTC did in this scenario for a very long time.

MCL1981 wrote:That was my understanding of traditional cab signalling as well. So this incident really isn't a PTC victory then, is it? The old cab signalling system would have signaled the engineer to stop. And if the engineer was asleep, it would have stopped itself. The train would have come to a safe stop in either case. The only way this would be a PTC save is if the engineer was intentionally ignoring and overriding the restricting signal, which doesn't seem to be the case. I'm not sure I would call this a PTC victory. It's really just a different system that did the same thing the old system did.

I'm not saying PTC is useless or a bad thing. Just that this is probably not a shining example of it doing it's thing. Cab signalling has been doing what PTC did in this scenario for a very long time.

Yep, the Cab Signals worked real well in 1987 at Gunpow Interlocking in Maryland where Amtrak's Colonial hit those Conrail locomotives. There are lots of Cab Signal systems out there, only a few of which meet the standards to qualify as PTC systems. The UP will have to replace all the Cab Signals on their lines as they cannot guarantee that they can prevent a train from passing a stop signal. Of course in this case there were no Cab Signals installed on this BNSF line.

Your citing an example that is the exact opposite of the incident you posted about. PTC would not have stopped the Amtrak train any faster than the engineer did. They were practically on top of them when the Conrail locomotives ran through the switch. There was no time to stop the Amtrak train between switch being fouled and the collision whether it was eye balls, cab signals, light signals, or PTC. The Conrail train would have been stopped by either cab signals or PTC. Neither existed on their locomotive.

Did I say anywhere that PTC isn't needed or that cab signalling is the end all solution? No. All I said was that the incident you posted about would have had the same outcome with or without PTC. Relax.

MCL1981 wrote:Your citing an example that is the exact opposite of the incident you posted about. PTC would not have stopped the Amtrak train any faster than the engineer did. They were practically on top of them when the Conrail locomotives ran through the switch. There was no time to stop the Amtrak train between switch being fouled and the collision whether it was eye balls, cab signals, light signals, or PTC. The Conrail train would have been stopped by either cab signals or PTC. Neither existed on their locomotive.

Did I say anywhere that PTC isn't needed or that cab signalling is the end all solution? No. All I said was that the incident you posted about would have had the same outcome with or without PTC. Relax.

PTC would have stopped the Conrail locomotives, the Cab Signals w/o ATC did not stop them.

I know. I said that.