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pvmw
17th Jun 2016, 09:27
Spotted in the news this morning. OK, a derailement isn't common but it happens. What raised an eyebrow in this case was the following statement:-



A spokesman for Network Rail said: "An empty train travelled past a red signal outside Paddington station which activated an automatic derailment.

"No passengers were aboard and there are no injuries but some lines in to and out of Paddington are currently blocked.
That did make me wonder. Is there really a mechanism by which a train can be automatically derailed if it passes a red signal? If there had been passengers on board could an automatic derailment happen at a speed sufficient to cause injuries - bear in mind it was either departing or approaching a station so many passengers may have been standing, getting luggage from racks etc.

It all sounds a bit unlikely to me. There are better ways to stop a train if it passes a red. It might be a bit career limiting for the driver.

Allan Lupton
17th Jun 2016, 09:36
It could be that the red was guarding against a head-on collision on converging tracks - in the past that was often backed up by catch points which derailed the over-running train - as seen in this photo:
https://upload.wikimedia.org/wikipedia/commons/thumb/8/86/Catch_trap_drag.jpg/200px-Catch_trap_drag.jpg

rans6andrew
17th Jun 2016, 10:02
Ah, Goathland, Nice!

Tankertrashnav
17th Jun 2016, 10:26
So - another one of these then. ;)

https://upload.wikimedia.org/wikipedia/commons/8/85/SPAD_XIII_040510-F-1234P-019.jpg

nippy1975
17th Jun 2016, 12:21
The train passed a Ground Position Signal coming out of sidings at Danger. The points ahead of the signal are trap points designed to derail an unauthorised (by the signalman) movement away from any conflict point. The fact that the the whole of the train has passed the signal and become derailed is concerning as it meant the train came into contact with Overhead Line Equipment. This is the reason for the amount of disruption caused last night and this morning. If it hadn't hit the OHLE then the disruption would have been minimal, probably just one platform closed, enabling a full service to run.

nippy1975
17th Jun 2016, 12:34
It should be added, that trap points are fitted to non passenger lines. There are also systems such as the Automatic Warning System which applies the brakes if the driver fails to acknowledge a warning. This doesn't prevent a driver from acknowledging a warning and then accelerating passed a red signal, that is covered by the the newer Train Protection & Warning System, which will automatically apply the brakes if a train approaches a red signal too fast or passes it at danger. TPWS also provides safeguards if a train approaches some speed restrictions or buffer stops too fast. TPWS will not always prevent a train passing the signal at danger, but is designed to stop the train within a safety overlap at speeds of up to 100mph. Over this speed, the train isn't guaranteed to stop in the overlap but any effects will be greatly reduced. There is a further system fitted to the Great Western Line (and a slightly different version on the Chiltern lines out of Marylebone) known as Automatic Train Protection. ATP basically monitors what the driver is doing, prevents over speeding and also will brake the train of the driver doesn't react to cautionary signals. This was never fitted around the whole country due to cost, TPWS being cheaper. In the long term, this will all be replaced by Cab based signalling. TPWS isn't always provided at Ground Position Signals, it may have helped here as although the train still probably would have derailed, it wouldn't have got as far as it did. There has been one other SPAD/derailment here since I joined 23 years ago and that was approx 12 years ago. The train only derailed one bogie as opposed to the whole train being derailed here.

Super VC-10
17th Jun 2016, 19:20
http://www.railforums.co.uk/showthread.php?t=131754 (http://www.railforums.co.uk/showthread.php?p=2600262)

RedhillPhil
17th Jun 2016, 19:41
So - another one of these then. ;)

https://upload.wikimedia.org/wikipedia/commons/8/85/SPAD_XIII_040510-F-1234P-019.jpg



In the face of it almost certainly but let's wait for the RAIB report first eh?

Super VC-10
17th Jun 2016, 22:09
So - another one of these then

No, more a Mk I SPAD than a Mk XIII SPAD.

Tankertrashnav
18th Jun 2016, 00:06
Maybe, but I thought it was a really nice piccy!

westernhero
18th Jun 2016, 09:07
Later on there might be a review of the positioning of gantries in relation to the position of trap points, coming off at the latter you really don't want to hit the former do you ?

Blues&twos
18th Jun 2016, 11:13
Something a little unusual about this though to my (layman) mind, with the whole train being derailed. I don't know if this is likely at normal "sidings speed", but I'd be interested to find out from the rail professionals who post here.

Sultan Ismail
18th Jun 2016, 13:29
Something more than unusual here, how does a whole train nominally 8 coaches derail over trap points?
The trap points are intended to catch the first bogie and put it in the weeds. There is just not room to accommodate a train.
Can anyone provide a signalling plan for the area?

G-CPTN
20th Jun 2016, 13:35
Derailed London Paddington train lifted back on tracks (http://www.bbc.co.uk/news/uk-england-london-36569006).

Blues&twos
20th Jun 2016, 19:11
Ah, from that article it seems the train consisted of only two carriages. Even so, getting the whole thing off the road having passed a red in sidings still surprises me.

RedhillPhil
20th Jun 2016, 19:14
The speed restriction for where the train is(was) running is 25MPH.

Blues&twos
20th Jun 2016, 19:19
Thanks RedHillPhil. I guess at that speed it could be possible.

nippy1975
20th Jun 2016, 22:42
I'm very surprised at how far the train has come off. I have been a signalman for 23 years and had two previous derailments on trap point (1 at the set involved the other day) Both came off one bogie only. I'm looking forward to the report as I think it will be interesting.