Post A Reply
my profile
|
directory
login
|
register
|
search
|
faq
|
forum home
»
RAILforum
»
Passenger Trains
»
Amtrak
»
Metrolink head-on crash in Chatsworth
» Post A Reply
Post A Reply
Login Name:
Password:
Message Icon:
Message:
HTML is not enabled.
UBB Code™ is enabled.
[QUOTE]Originally posted by Geoff M: [QB] [QUOTE]Originally posted by delvyrails: [qb]Putting a freight train travelling on a single track and operating in the opposite direction in the space scheduled to be occupied simultaneously or nearly so by a passenger train should be outlawed.[/qb][/QUOTE]Sorry but that is simply impractical. Firstly, it could equally have been another passenger train coming instead of a freight, so your solution doesn't improve the situation there at all. Secondly, doing this would imply absolute priority to passenger trains with full protection up to [b]and into[/b] the next siding - which then leads you to ask the question about what happens at the end of the next siding - in other words, you're just shifting the problem to the next siding instead. No freight would ever be able to move within the vicinity of a passenger train. Thirdly, you could have a case of a passenger train with minor casualties but the freight which it collided with was carrying toxic chemicals which leaked and caused an environmental disaster instead, so again no improvement on the situation. American - in fact virtually all the world's - signalling works mainly on the principle that trains will stop at an absolute stop signal. Assuming in this case that this is what happened, and it wasn't some other failure, then for whatever reason one of those trains didn't - and there was no protection in place to allow for that. There are various ways of enforcing that, as has already been discussed by others. After the UK's Clapham Junction accident, it was recommended that Automatic Train Protection be fitted throughout the network. Too expensive. So 20 years later we now have TPWS installed at all controlled (aka absolute stop) signals and selected other high risk signals. Rollout across the entire network took about 3 years IIRC. This consists of an arming loop and a trigger loop set a certain distance apart in the track, and a certain distance before the stop signal. If the train passes the trigger loop after the arming loop within a fixed interval of time then the brakes are applied and the train should come to a stand safely. At the signal itself is another arming and trigger loop right next to each other so anything correctly stopping at the signal and then restarting while still red will get tripped at the signal. Now, I wasn't particularly impressed at this as it was only fitted at certain signals and seemed a cheap and dirty solution, but it does appear to have worked - it has stopped a number of trains that were at risk of colliding. IF, for example, this was a case of running a red light then TPWS would have prevented this particular accident - but I'm not saying that this was the case, which is up to the investigators to determine. I'm also not saying that TPWS is the solution to this - but the point is that a solution can be provided cheaply (for TPWS the relay circuitry is actually pretty simple and can be cut into existing circuitry using spare contacts. Microprocessor logic is equally simple). Rules and laws are all good and well but it's the enforcing that is the problem. Geoff M. [/QB][/QUOTE]
Instant Graemlins
Instant UBB Code™
What is UBB Code™?
Options
Disable Graemlins in this post.
*** Click here to review this topic. ***
Contact Us
|
Home Page
Powered by
Infopop Corporation
UBB.classic™ 6.7.2
Copyright © 2007-2016
TrainWeb, Inc.
Top of Page
|
TrainWeb
|
About Us
|
Advertise With Us
|
Contact Us