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Re: What is the purpose of the pre-assembled SMART switch at Petaluma station chalkmarked "gauntlet?
Author: OldPoleBurner
Date: 04-20-2013 - 23:35
A few station platforms on the Northeast Corridor use a similar gauntlet.
Even with Amtrak's full size trains (slightly wider than a freight car) and high level platforms; they still prove useful, and not just to shift freight trains further away from the platform. In fact, they don't even bother to shift the freights at most platforms. But where they do, you only need a couple of feet, so frogs (indeed a major maintenance expense) are not required in order to do the job and are of no practical use; and neither is the extra r.o.w. required in order to use them.
The faster a train goes, the more dynamic sway there is to contend with. So the farther away it needs to be from obstructions such as platform edges. Above a certain speed, there is the risk of swaying into and scraping a closely spaced high level platform. But even if there was no sway factor, the wind blast from a 120mph train blowing through a station only a couple of feet away on the platform, can be very dangerous to passengers that may be waiting for a following train.
So shifting the high speed traffic away two or three feet from the platform edge is a very good idea. But it should always be the traffic stopping at the platform that veers off tangent, not the through traffic. But being a California agency where top decision makers never seem have any real expertise in such matters, SMART is dumb!
As the the mentioned South Shore head-on crash at the end of a gauntlet, the use of a gauntlet over a bridge was by itself not even slightly relevant to the accident; despite some very premature and politically motivated remarks by certain officials (including the NTSB). The pure fact is that the bridge was two narrow to accommodate the two main tracks of that line. This is not an uncommon problem at tunnels and bridges.
Other than to expand the bridge or tunnel (often cost prohibitive), the only two options available are a short gauntlet or single track section. To suggest that a gauntlet track is unsafe and caused the accident, and should be done away with; is exactly as nonsensical as to suggest that a single track section is unsafe and should never be used.
Of course, if humans were perfect, and even if machines like PTS were perfect (they are not!); then no train would ever disregard an approach aspect and therefore fail to stop at the red. Yep! -- that was the sole cause. And would have remained the sole cause, even if the violated absolute signal had been protecting a single track section instead of a gauntlet. The accident would have happened regardless. Only stopping behind the red signal would have prevented it - period!
Even with Amtrak's full size trains (slightly wider than a freight car) and high level platforms; they still prove useful, and not just to shift freight trains further away from the platform. In fact, they don't even bother to shift the freights at most platforms. But where they do, you only need a couple of feet, so frogs (indeed a major maintenance expense) are not required in order to do the job and are of no practical use; and neither is the extra r.o.w. required in order to use them.
The faster a train goes, the more dynamic sway there is to contend with. So the farther away it needs to be from obstructions such as platform edges. Above a certain speed, there is the risk of swaying into and scraping a closely spaced high level platform. But even if there was no sway factor, the wind blast from a 120mph train blowing through a station only a couple of feet away on the platform, can be very dangerous to passengers that may be waiting for a following train.
So shifting the high speed traffic away two or three feet from the platform edge is a very good idea. But it should always be the traffic stopping at the platform that veers off tangent, not the through traffic. But being a California agency where top decision makers never seem have any real expertise in such matters, SMART is dumb!
As the the mentioned South Shore head-on crash at the end of a gauntlet, the use of a gauntlet over a bridge was by itself not even slightly relevant to the accident; despite some very premature and politically motivated remarks by certain officials (including the NTSB). The pure fact is that the bridge was two narrow to accommodate the two main tracks of that line. This is not an uncommon problem at tunnels and bridges.
Other than to expand the bridge or tunnel (often cost prohibitive), the only two options available are a short gauntlet or single track section. To suggest that a gauntlet track is unsafe and caused the accident, and should be done away with; is exactly as nonsensical as to suggest that a single track section is unsafe and should never be used.
Of course, if humans were perfect, and even if machines like PTS were perfect (they are not!); then no train would ever disregard an approach aspect and therefore fail to stop at the red. Yep! -- that was the sole cause. And would have remained the sole cause, even if the violated absolute signal had been protecting a single track section instead of a gauntlet. The accident would have happened regardless. Only stopping behind the red signal would have prevented it - period!
