 |
Re: LA Times story on Metrolink vs BNSF incident at Rialto [link]
Author: OldPoleBurner
Date: 11-22-2008 - 19:53
Indeed I wondered about the systems apparent sensitivity too. However, the system is brand new. The engineer was new - as most of them were - having recently transferred from Trax light rail or UTA bus divisions. They will get used to the system's requirements. That the engineer was in final license training is also possible, thus accounting for the presence of FRA personnel in the cab of several trains I saw.
The apparent tightness could have also been peculiar to the particular cab car I happened to ride. Also, my engineer may have been slightly slow in responding. I couldn't tell for sure, as I could not easily see the cab signal indicator from my seated position - and probably could not hear the softer alerter either. If its timing was a bit tight, it is no big deal to adjust it - just a quite ordinary part of routine maintenance, actually.
But any more than a few seconds delay after passing a restrictive boundary, whether it be plain old ABS, ATC or a so-called PTS / PTC system, or a even a fully automated BART train, would suggest non-compliance with the aspect. The rules require an immediate brake application for darn good reason, having to do with allowing enough room for the worst case braking scenario (apparently needed in this case). Aspects must therefore be promptly enforced and then followed up with continuous braking supervision until the over-speed condition has been fully remedied.
That many existing ATS or ATC systems (especially on freight trains) currently allow the engineer to merely acknowledge the restrictive aspect without actually enforcing the it, and then supervising the braking, is why none of these systems can currently provide positive train separation, as now required by law. This new system provides all the features necessary for complete "Positive train Separation" and is already in compliance with the new PTS law. Now that is progress! But it manages this progress mostly with already commonly existing and in-service infrastructure. That makes the PTS concept much easier to accomplish.
But no matter what (failsafe) technology is used; if you want your "Positive Train Separation" system or whatever, to actually and positively keep the trains apart, that system must react similarly to this one. If you don't think so, you need to go argue the point with Sir Isaac Newton.
But after 38 years in the automatic train control field, I have learned, as we all have, to NOT argue with Newton's laws. Nature always wins.
OPB
The apparent tightness could have also been peculiar to the particular cab car I happened to ride. Also, my engineer may have been slightly slow in responding. I couldn't tell for sure, as I could not easily see the cab signal indicator from my seated position - and probably could not hear the softer alerter either. If its timing was a bit tight, it is no big deal to adjust it - just a quite ordinary part of routine maintenance, actually.
But any more than a few seconds delay after passing a restrictive boundary, whether it be plain old ABS, ATC or a so-called PTS / PTC system, or a even a fully automated BART train, would suggest non-compliance with the aspect. The rules require an immediate brake application for darn good reason, having to do with allowing enough room for the worst case braking scenario (apparently needed in this case). Aspects must therefore be promptly enforced and then followed up with continuous braking supervision until the over-speed condition has been fully remedied.
That many existing ATS or ATC systems (especially on freight trains) currently allow the engineer to merely acknowledge the restrictive aspect without actually enforcing the it, and then supervising the braking, is why none of these systems can currently provide positive train separation, as now required by law. This new system provides all the features necessary for complete "Positive train Separation" and is already in compliance with the new PTS law. Now that is progress! But it manages this progress mostly with already commonly existing and in-service infrastructure. That makes the PTS concept much easier to accomplish.
But no matter what (failsafe) technology is used; if you want your "Positive Train Separation" system or whatever, to actually and positively keep the trains apart, that system must react similarly to this one. If you don't think so, you need to go argue the point with Sir Isaac Newton.
But after 38 years in the automatic train control field, I have learned, as we all have, to NOT argue with Newton's laws. Nature always wins.
OPB
