On the road, there's one traffic light (or set of lights) controlling all lanes.
On the railway, there is one signal per track. On curves, gradients etc, the psychology of reading through/across is very real.
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Report of collision Bedford (Elstow) - 19/06/26
- Thread starter E16 Cyclist
- Start date
On the road, there's one traffic light (or set of lights) controlling all lanes.
On the railway, there is one signal per track. On curves, gradients etc, the psychology of reading through/across is very real.
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Hairy Bear
Member
Yes, he cleared the junction and just kept on accelerating. Don't believe he read thru, or across, he was experienced, but why,
Don't think we'll ever know.
Signal Head
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I must have been mistaken in my recollection of where (in the video) 76MPH was reached then, but it was reached before the area where the collision occurred, so it still looks like the acceleration of 1H46 was in line with that when driving on Greens.
Haywain
Veteran Member
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A slight aside to all this; on the BBC local radio* news yesterday they had a solicitor ("acting for the victims") demanding that Network Rail should accept responsibility and apologise for the crash as a result of their failure to install TPWS at the signal (WH154).
* BBC Three Counties
* BBC Three Counties
To me it seems a classic "looked but failed to see" cognitive error or similar. He did acknowledge the AWS but did not see the red aspect and forgot about it. It likely will be as simple as he was expecting the green to clear and had done it 200 times before, except this time the signal didn't clear and he did not notice it despite looking out of the front of the train.
This phenomenon is common when looking at expected, daily encounter scenes like junctions, runways, and railway lines, with the brain prioritising familiar patterns over actual data. See also the perception biases at the Stratford LUL incident with the guy falling off the platform.
It's also been cited by RAIB in regard to crossing incidents.
bramling
Veteran Member
I would be inclined to go with the above, but for one thing - there was no last minute reaction. I'd have still expected the driver to have suddenly noticed the red at the last minute, especially if it ends up being the case that there was no issue with its sighting (unless I've missed anything I don't think RAIB have commented on this). Except in the case of misreads, it is still very unusual for drivers to completely disregard a red aspect, there is normally some kind of reaction even if too late.
Red lights tend to promote an instinctive response in drivers, it is more likely to be yellows that lull into a false sense of security.
I wouldn't be ruling out some kind of distraction, though if there was we may never know.
Going back through recent memorable accidents caused by SPADs, Newton was a "start up against" so not completely relevant, Cowden had the complications of thick fog, not perfectly illuminated signal and a distraction in the cab, Southall was almost certainly distraction plus no AWS, Ladbroke Grove generally regarded as a misread. Two that could be relevant are Purley for sure, and possibly Watford South Junction, in both cases there was a last-moment reaction at the red.
The acceleration rate decreases with increasing speed as the train resistance increases (quadratic realtionship) and TE decreases (inverse relation) so there is no simple answers to your question.
(I have to do these calaculations professionally)
Signal Head
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I think the intention of the delay to 'better than Yellow' was to force an AWS caution indication for a diverging movement, which at first thought seems a sensible idea - the train needs to be running at a reduced speed for the junction, so ensure the driver doesn't get an AWS 'bell'; the caution indication reinforces the junction indicator, not the aspect.
However - and here's where the law of unintended consequences steps in - doing that weakens the traditional meaning of the AWS.
Consider an arrangement where the signal releases straight up to Green (if aspects ahead allow) well before the train reaches the AWS magnet, which in most cases it probably will because there won't be anything immediately ahead, drivers are now used to getting a bell, so when on the odd occasion the signal cannot go all the way up to G, there's a audible difference as well as visual. Now the AWS caution reinforces the aspect, not the junction indicator.
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That's about 27 fps in 31 secs or roughly 3% g which sounds plausible. Assuming it's linear which it won't quite be, but 76 is a long way below the top speed of 110mph.
Also by my calcs the rated 1550 kWh (at the rails) would at 58 mph (26 m/s) produce ~55 kN tractive force so capable of accelerating 169 tonnes at a maximium of 3% g (not allowing for drag) which is pretty consistent.
However the wikipedia article https://en.wikipedia.org/wiki/British_Rail_Class_360 says max acceleration is 3.2 fps^2 which is 10% g so I am not sure how to reconcile these figures, perhaps that is from a standstill?
== Doublepost prevention - post automatically merged: ==
Agreed. But the rough calcs above show we are in the right ballpark in thinking the train was still accelerating, rather than cruising at a speed appropriate for double yellows.
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The
The max rate is only applicable at very low speeds (low = less than Usain Bolt pace) and taper off rapidly above low speeds.
Annetts key
Established Member
I'm a union man, and I know that the RMT would not stand in the way of improvements to systems that improve the reliability of systems that help with safety. Yes, the unions would want the relevant company to use the existing (agreed) consultation process. But that can be done (when the companies want to) in less than six weeks.
The hold up with changes like this, is more often a lack of money or resources. Or the company having to get a standard changed. Or having to go back to the original equipment manufacturer / supplier and obtain their permission.
On a non-safety system, but a system that was part of the operational signalling system, when some hard disk drives failed, it took months to persuade my manager to buy new drives. And that was partly because the available new drives were higher capacity compared to the failed drives (the old and the new were from the same manufacturer). The railway likes like for like replacements as that is the easiest way to be safe.
The fundamental principles of lights on sticks is that the drivers see and respond to them. If that fundamental principle cannot be relied upon, then the whole system must be considered broken.
The whole reason that automatic signal sections exist is because these are far cheaper than controlled signal sections. That's because far less equipment is needed, making them simpler. They still provide the required safety of protecting the line ahead if a train is in the signal section ahead.
Yes, you can put in place mitigation measures for a particular location for particular circumstances, but what about everywhere else? The railway is not going to spend millions of pounds putting in mitigation measures across the whole country. And besides which, if there was millions of pounds available, there are far better and more effective ways to spend that money.
If the fast train had stopped just short of the signal, do you think that would have made any difference here? The automatic signal would have still been showing a green aspect. Therefore going on the available information, the crash would have still occurred.
Indeed, even if the automatic signal above the fast train had been showing a red aspect, I strongly feel that the crash would still have happened. By the time the driver of the slow train would have reacted (if it was the signal that was seen before the rear or the tail lights of the train ahead), the slow train was too close, at the speed it was travelling there was insufficient distance for the brakes to bring it to a half before hitting the fast train.
Yes, that will go nowhere. Network Rail simply has to demonstrate that it followed the standards and the law. If they really want to blame or point fingers, they should be be aiming at past governments.
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The fact that TPWS was not legally required at this signal (due to an exemption from the Railway Safety Regulations) is not a defence for Network Rail in a civil claim. It simply means they were not committing a criminal offence under those Regulations.
The question will be whether the failure to fit TPWS at plainline signals such as WH154 amounted to negligence and/or a breach of the duty of care under the Health and Safety at Work Act.
68000
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On the subject of GSM-R and no independent source of power, this was identified during the development of GSM-R and the operational trial. A 'UPS' was fitted to some of the ScotRail EMU fleet so that GSM-R can source power in the situation where the train power is lost. I know the batteries had to be replaced every five years (or possibly longer). I have no idea if they are still installed and why other EMU fleets does not have them.
Nobody will ever really know why the driver passed the red signal without reacting to it.
Using my driver's head my thoughts tend to lean towards after passing the one yellow and starting across the crossover their risk priority switched to their speed across the crossover and ensuring their train did not exceed the 50mph PSR for that move. Then thinking how long before the whole train was clear before accelerating the train away.
Driving upon previous experience at the same location time and time again is a huge factor. The driver had probably never seen the next signal showing anything other than green so were conditioned to doing the same thing again and again at that location.
The fact that the previous signal had been a one yellow may have slid down their short term memory list and therefore the wrong risk was prioritised with devastating consequences. And for reasons we'll never know the driver didn't react to the AWS for the red signal, or the signal itself. We are only human, and therefore fallible.
A tragic sequence of events sadly.
Using my driver's head my thoughts tend to lean towards after passing the one yellow and starting across the crossover their risk priority switched to their speed across the crossover and ensuring their train did not exceed the 50mph PSR for that move. Then thinking how long before the whole train was clear before accelerating the train away.
Driving upon previous experience at the same location time and time again is a huge factor. The driver had probably never seen the next signal showing anything other than green so were conditioned to doing the same thing again and again at that location.
The fact that the previous signal had been a one yellow may have slid down their short term memory list and therefore the wrong risk was prioritised with devastating consequences. And for reasons we'll never know the driver didn't react to the AWS for the red signal, or the signal itself. We are only human, and therefore fallible.
A tragic sequence of events sadly.
Deepgreen
Established Member
Often not the case at complex road junctions.
InvernessTMD
Member
A consumer grade UPS capable of running a desktop computer for a couple of minutes (so you can save your work and turn off your computer safely) is only a few hundred pounds. A GSM-R unit would presumably use a tiny fraction of the power a computer uses - so a much smaller unit would suffice. Accounting for the ballooning of costs associated with hardware built to the standards of the railways, I'd wager it would still be under £1k per UPS system - chump change compared to the rest of a multiple unit, no? If the only reason for this not being fitted network wide is cost saving, that's unbelievable.
No, indeed, but as a driver I have no expectation that different sets of lights are linked in any way, and each needs to be treated on its own. Unlike railway signals in which they're clearly linked. I've never found road traffic signals confusing on this basis, but I note that some people may do, so the designers may need to take this into account in some way.
In particular, "read through" is a major mistake with road signals whereas on railways it's perhaps more understandable. I can think of potentially confusing road junctions near me with multiple sets of signals which - to me - are perfectly clear but which might be wrongly interpreted by inattentive drivers perhaps.
I might be misunderstanding you, but there was a last minute reaction from the driver. The RAIB interim report states:
We do indeed see it step up to green if WH154 and beyond are off .
Purple Train
Established Member
I think @bramling means a reaction to sighting the red signal at the last moment.
Steve Harris
Established Member
That is exactly how I read @bramling 's post.
It seems obvious that the driver did not *see* it even if they were looking at it. @FR510 shares the same instincts as I do as to the most likely sequence of events.
norbitonflyer
Established Member
Not always, by any means. I've been caught out when an amber came on, only for the subsequent green to be an arrow for a direction I wasn't planning on going.
At least on the railways there are rules setting out correct practice and it does not vary within a few hundred yards.
On the approach to Cambridge along the old A10 there is a right turn (arrowed) to the housing estate that was the chemical works. @Magdalia and other locals will know where I mean.
As you approach from the S, at first you can only see a red light in the centre of the road so you have to prepare to stop.
Then further on round the lh bend you can see the green forward arrow on the lhs and can accelerate again.
The junction with the B road at the bottom of the extract is broadly similar in layout and visibility, but there there is a green filter on both sides which is obviously better practice.
== Doublepost prevention - post automatically merged: ==
Another bit of poor psychology. It used to be the case that filter arrows did not have an amber phase at all, maybe that was why.
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norbitonflyer
Established Member
They usually don't, but in some places (the A308 near Ashford for example) where the straight ahead and right turns have separate phases, they each have their own red, amber, and green-arrow lights.
The short answer is yes. Pretty much to the dot. Regardless of units driven.
They usually don't, but in some places (the A308 near Ashford for example) where the straight ahead and right turns have separate phases, they each have their own red, amber, and green-arrow lights.
... except that one of the straight-ahead red lights (on the rhs) is completely out.
bramling
Veteran Member
Apologies I don’t think I was fully clear. I meant a last-minute reaction to the red aspect, not the train ahead. IMV this seems the unusual element to it, unless there’s something about the signal sighting that we don’t yet know.
My first reaction to this accident was thinking that the 810 might have stopped close to the limit of the overlap, and the 360 didn’t have enough railway to stop. I was somewhat surprised when it emerged the 360 had travelled some way further south than that. That would be a far more logical, if unlucky, scenario.
== Doublepost prevention - post automatically merged: ==
If it’s the case that the driver was looking at it, for this to be the case I’d have thought it would then have to require there to be some deficiency with the signal, either in terms of its sighting, position or performance.
It’s an interesting discussion, and there is no doubt a lot still to emerge. Suspect we may never fully know the answer, unless RAIB manage to find something that gives a strong clue.
I wouldn’t be surprised this could end up being one of those incidents where even RAIB are only able to go as far as offering possibilities.
What we probably can say is that acknowledging the AWS doesn’t really tell us much apart from that the driver was conscious, as there’s a history of incidents where AWS warnings have been acknowledged in this way.
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By looking at it, I mean that it was simply in his field of view, rather than focused on it.
Either way I expect RAIB will only be able to offer a range of possibilities but I hope some valuable human factors learnings come out of this. Are drivers taught about human factors in training?
Either way I expect RAIB will only be able to offer a range of possibilities but I hope some valuable human factors learnings come out of this. Are drivers taught about human factors in training?