The Planner
Veteran Member
- Joined
- 15 Apr 2008
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Most of it south of Crewe could do that now, but wouldnt give you 20% you could utilise.
True, but I believe it was designed for 140mph. Signals spaced closer for 125mph might allow 2 1/2 minute headways, nearly a 20% increase in capacity.
Correct. When the HSTs started, 125mph had two drivers and AWS, and subsequently ATP was installed as well as a pioneer installation on the eastern end of the line.When the HSTs were introduced in the GWML, wern't two drivers required at all times up until the early 1990s?
Required over 110mph if I'm correct?
...so are these things red railway signals that can actually be passed at danger without a calling on aspect? Just a note that it is a repeater - which must be unique to LU! I believe BR introduced banner repeaters precisely so that there would never be a situation where a conventional signal was passed at danger without a special authorisation.
Correct. When the HSTs started, 125mph had two drivers and AWS, and subsequently ATP was installed as well as a pioneer installation on the eastern end of the line.
Eventually the two drivers requirement was indeed removed in the early 1990s, as you describe. But there were still the other measures, which had been used in justification of going down to single driver.
Then the ATP installation fell into disuse, as the first privatisation TOC contract had not stipulated it, so the training etc was not continued, although train and track were still fitted. But there was still AWS.
Then the compulsory AWS 125mph requirements were relaxed. I'm not sure, but I think it was justified on the basis that there were two drivers . If failed, the "signalman was to be advised", to take extra precautions. And, if possible, the set was to be turned on a triangle so the failed unit was trailing.
Railtrack saw turning on a triangle, eg at Landore if leaving Swansea with a failed AWS, as an "extra movement". For which they made an extra charge. So it was thus seen as not possible.
The procedure for "advising the signalman" was very casual, the driver just informed control, who had no formal procedure for passing this on, or what the signalman should then do.
So. 19 September 1997. Train leaves South Wales with known failed AWS, not turned at Landore to run good cab forward, one driver, not trained in ATP operation, so switched off. Message sent to control about the AWS was just scribbled on a Post-It and nothing more was done with it. Running at full 125mph approaching Southall in 4-aspect territory. No second driver looking out. No working ATP. No working AWS. No message to signalman to take extra precautions if making a crossing movement in front. You know the rest.
Some may not be aware of the Signal Repeating AWS (SRAWS) experiment of the 1970s, on the Bournemouth-Southampton Up line, which the east end cabs of the 4-REP units (which always led REP/TC combinations eastbound) were fitted with, as well as trackside. An extra panel for the driver showed the last of the four aspects, and there were three acknowledgement buttons alongside the restrictive aspect lights which had to be acknowledged appropriately, instead of the normal AWS single button. I think there were different warning tones for the different aspects as well. It was an excellent advance on traditional AWS, which is nothing more than the original GWR 1910 concept, and unfortunately fell to one side just because of personalities; it was a Southern Region instead of BR Headquarters idea.Drivers reset the AWS so regularly that they are often ignored and often simply forgotten about. Even having the sunflower doesn't mean the Driver notices or acts upon the warning.
Except if they had sneezed past a yellow aspect they would have acknowledged an AWS warning. If they had a green the signal previously then they know they have just passed a yellow and brake accordingly. If they are still somehow unsure (unlikely) then i'd expect them to act as though they had a cautionary aspect.
Regardless of this it's extremely unlikely anyway given the vast majority of signals are sighted for a few seconds beforehand, it would need to be a lengthy sneeze.
It's just a yellow with little sighting time before a potential red.driving a train at 125mph with no working AWS.
If the horn is missed and the button not pressed the brakes would go on. I'm sure if the horn was inaudible then drivers would complain and something would be done....but perhaps not so aware of the AWS horn (or its modern equivalent) and the visual indicator/reminder that you have just passed a signal with a restrictive aspect. The horns used to be deafening, especially if you were an extra person stood up in the cab with your back to the engine-room bulkhead!
Only if "reactivation" had included fitting ATP to the Thames Train that SPADded, which was never intended to be so fitted. The GW train was under clear signals and going too fast to stop whatever the ATP might have done in the short time available. In fact TPWS would have prevented Ladbroke Grove, but the request for funding was still sitting on Prescott's desk.If the ATP reactivation had been done fully Ladbroke Grove would not have happened.
Such an interesting question that it deserves its own thread.Question (which I have asked elsewhere and not got an answer): when was the last UK rail accident resulting in at least one fatality that could only have been prevented by ATP i.e. TPWS and/or AWS would not have prevented it?
I believe 3-aspect signalling is in place on everything west of Tilehurst, including such complex layouts as Didcot and Swindon.
It is very common for a nominally 3-aspect signalled line to have some closer spaced 4-aspects approaching stations. This is to provide some 'closing up' functionality so if there is a train in a platform the next one following behind can get closer to the platform to wait clearance.Worth noting that it isn't entirely 3 aspect signalling West of Tilehurst. There are pockets of 4 aspect signalling approaching various locations, such as Didcot, Swindon and Chippenham.
No... I am fully aware of the AWS horn as well!
It’s off the end of the 125 stretch, but a single yellow on the 100mph at Bathford approaching Bathampton Jcn usually produces a brake application sufficient to knock a cup of coffee over. The poor sighting of the signals and very short (approx 1.5 mile) section has long been hated by drivers.
Here's a possible headscratcher for you with a fairly tenuous connection to the OP's question. North Wales only has one 4 aspect signal in its entirety. Is this true or false? Bonus point if you can place it/them!
The Met has three and four aspect signalling between Harrow and Amersham on a 60mph railway.London underground signalling is two aspect with repeaters (distants) only provided for badly sighted signals. I know line speeds are far lower but at certain locations the driver has very little reaction time indeed. They also have no AWS, TPWS or DRA and the train stop system only intervenes when it's too late. A very different world from the one upstairs.
The Met has three and four aspect signalling between Harrow and Amersham on a 60mph railway.
Here's a possible headscratcher for you with a fairly tenuous connection to the OP's question. North Wales only has one 4 aspect signal in its entirety. Is this true or false? Bonus point if you can place it/them!
Ooh, interesting! Being from Llandudno / Deganwy / Junction my "it's the centre of the universe" ridiculous bias wants it to be there, but I'm not that daft!
I've been wondering about where you might want it if there's a difference between line speed and what the trains used can do, but thought these days every planned train can do 90.
Then I thought about stopping patterns, and the only stretch that came to mind was Rhyl to Colwyn Bay, which until recently had the down platform on a loop. But it feels more likely that would be handled by timetabling?
Then I thought about the Conwy bridge, but seemed unlikely.
My random guess is going to be there is one, on one side of the bridge between Bangor and Anglesey. I guess the Anglesey side.
I know my guesses will completely wrong!
The reply wasn't just to you, it also quoted someone who was being quite, I think deliberately, offensive about the Southall crash, who latched onto your post about potentially missing a signal by sneezing and AWS. I half wish I'd not replied here, because he's presumably just a disrespectful arse looking for attention.
This was installed in 1960, when the line here, although owned/signalled by LT, was still shared with BR express steam-hauled, vacuum braked trains from Marylebone to Nottingham etc via Aylesbury, and even heavy unbraked freights. It's the only part of joint BR/LT running that was signalled by LT. All the rest were BR signalled.The Met has three and four aspect signalling between Harrow and Amersham on a 60mph railway.