Hello all, Currently playing ECML and wondering with 4 aspect signalling if it's expected that after a green the expectation is the next signal aspect will be a double yellow. As per the image I found below? Just want some clarity on how it all works. And likewise for a double yellow do you expect next signal to show a yellow etc.
That diagram is correct. Worth noting on a portion of the ECML you will also have flashing green around stoke bank, but it's meaningless as the limit is 125 anyway. That was set up when they were looking at 140mph running.
The sequence is green, double yellow, yellow, red. Whenever you approach a signal, always assume the next signal is not the same, will prevent you accidentally passing a red signal. At a double yellow, start slowing down. At a single yellow, prepare to stop as the next one may be red. Ignore flashing green signals, they are irrelevant. Treat them as regular green signals.
Ah that clears things up. So should I drive as though the next signal could be such aspect. As in reduced speed so I can prepare in time or drive at full line speed.
I drive at line speed when a green signal is shown. The Azuma's brakes allow braking to commence upon sight of a double yellow for a reasonably comfortable stop before a red in most situations on the East Coast Mainline. If you have reason to believe that the next signals may be restrictive (for example, the signals you approach change from double yellow to green repeatedly), then you may wish to slow down a bit, but there is nothing wrong with line speed past green signals.
samuelpower2001 If you have the track monitor up in the top right too, you can see the next few signals as well to help.
Not always the case when you pass a grean signal or ANY signal for that matter never assume this is what we are taught as real life drivers. You do not ignore flashing greens they are there for a reason and just confirm to the driver that in a 4aspect signaled area that the next 3 signal sections are clear a driver would never ignore any signal. You drive the train at the line speed and adhere to the signals you are next approaching. If you are doing line speed and do come across double yellows then start braking. A single yellow will also not mean the next signal is red it could be approach controlled and the single yellow is displayed to slow you down for a diverging route. It should also be noted that signals are placed in accordance with being visible to a driver that they will be able to stop a train safely at a red they are placed in parts and have the speed of the fasted train and the weight of the haviest train in mind so that they will be able to stop.
Seems weird that drivers are taught the next signal may show the same aspect. I'd have thought they'd be taught that they are not guaranteed a free path at the next signal. Weren't flashing green signals put in place to indicate line speed increasing to 140mph? As this is currently not in place, wouldn't that mean you can just treat them as a regular green signal? Or is teaching drivers to watch for these signals to prepare them for when the line speed does increase? Or do they serve another purpose? Isn't it best to assume when approaching a single yellow that the next one is red unless you specifically know you're taking a diverging route? And don't diverging signals flash? If you know the next signal is a single yellow and that you are not to diverge, would you still prepare to stop? Also, just to note I was talking in the context of TSW. So obviously some things real drivers are taught are irrelevant.
I never said drivers are taught the next signal may show the same aspect please read what I said before making stuff up. I correct you when you said “whenever you approach the signal ALWAYS assume the next signal is not the same”. A driver will never ALWAYS assume anything they will drive to what they can see at the line speed determined. It’s what we are trained to do we never assume anything IRL. you are correct in that you will never assume a single yellow will change the red ahead of it approach controlled I should have worded that better but when approaching an approach controlled area proving the next section is clear and the route selected the red will clear when the timing section has detected a train in that section for the time. This is why approach control will slow trains down.
I just didn't interpret what you said right, nor did I appear to have used the right words. It does happen, so please don't assume I'm making stuff up. There's always a chance of something going wrong, so you'd presume it may so you are prepared for it. I always do, then again I tend to have a pessimistic approach to things so that's probably why.
yes there is always a chance things go wrong and when they do the signalling system is designed to be fail safe so when it does and it is very rare the signals will automatically go to danger but that is a different topic and not what is being discussed here. it is nice you try and answer questions to help others. However when someone who does the job daily and has done for a number of years corrects the parts you get wrong, accept you are wrong and move on. There is nothing wrong with being wrong.
I know how railways work, I just struggle to put the words down to paper, the end result isn't what I actually want to say most of the time. It is nice to have someone with more knowledge (given an actual driver would know more than me) to be able to give proper insight though.
It's great DTG decided to implement these in ECML but unfortunately I think these are bugged ..... during a run recently I had a flashing green followed by a double yellow, which I think is not right.
Thank you. I could have gone into it a bit more specific as there is more to the signalling but didn’t want to over complicate it as the basics are enough for a simulation game lol.
That’s correct that the trial use of flashing green aspects was to enable 140mph running. However, it was only ever done with test trains - never with trains in normal passenger service - and there is now no intention that it ever will be. The decision was taken that any train which was to exceed 125mph in the UK must have in-cab signalling (such as ETCS, currently being rolled out on the East Coast Mainline). As to why flashing greens still exist, I don’t actually know - maybe someone else can advise. I suspect that when a train is travelling at 125mph and a signal which the Driver knows to be capable of displaying a flashing green aspect instead displays a green aspect, the Driver probably shuts off power. This allows speed to drop away a little and decreases the likelihood that the next signal is still double yellow when the train reaches it (i.e. “don’t chase the yellows”). As well as having safety benefits, such an action reduces energy usage and brake wear. Whether that’s the reason for retaining the flashing greens, though, I don’t know.
That would be due to the numerous level crossings on the route. Until the barriers go down the signal protecting the crossing will stay yellow. That's what I've read at least.
That may be the reason for the double yellow, but the point is that the signal before it should be green. You shouldn't be able to get a flashing green, then a double yellow. The sequence is flashing green, green, double yellow, single yellow, red.
Basically. Too expensive to remove, so just gets left in place. Get it alot with equipment taken out of use, it's too expensive, especially in SSI areas, to rewrite the coding, so it gets left in until the next overhaul.
I will be honest my brain is rather tired tonight so will only scrape over the surface to clear a couple of things I have seen here which stick out to me. The flashing greens on this section are to be treated like any regular green aspect, though it can be useful for when you do get a green rather than a flashing green so you shut off to avoid having to deal with double yellows, often it just means they've been a bit slow with one of the crossings (it does not happen as often in real life as TSW, but does happen). As to why they lasted so long, very much a case of if it ain't broke don't fix it and as per above they don't pose a safety risk in any way so the cost to remove them isn't worth it. Once we go fully digital in a few years they'll be gone for good though.
Thanks, always good to hear from those in the know. Just one thing to check which I always thought of as a bit of a flaw in the ‘flashing greens’ concept, but perhaps I’m missing something. With yellow being ‘caution’ and double yellow being ‘preliminary caution’ then, for a 140mph train, green effectively becomes ‘preliminary preliminary caution’. i.e. it requires the Driver to take action to slow the train. However, I assume I’m right in saying that, even in areas with flashing greens, a green aspect is accompanied by an AWS bell, not a horn. Isn’t that a bit of a mixed message for the Driver? The signal aspect says ‘slow down’ but the AWS audible indication says ‘clear’?
As far as I know, Green is treated as proceed at line speed, rather than a 'preliminary caution'. So I'm not sure where you're getting that trail of thought from? Obviously route knowledge comes in to say you should expect x signal to be at yellow on the approach to..... But the AWS serves only as an indication that a drivers input is required, and as a green signal is an indication that the line is clear and safe to proceed at the marked line speed
Yes, but the original intention of the flashing greens trial was that it be used for 140mph running (even though in the end it was never actually done in passenger service).
But the intention of the flashing green concept was that for a train travelling at 140mph, green would mean reduce speed to no more than 125mph - making green (effectively) a cautionary aspect for trains travelling at that speed. The AWS bell therefore doesn’t seem appropriate.
That would have required an all new type of AWS magnet and interface, which I guess is probably another reason why it wasn't rolled out further
I think it was just meant to be the standard TPWS, but because obviously you’re going to fast to read the signal properly in time the project was abandoned, which is also why trains can’t go 125mph+ with out in cab signalling.
Effectively, yes, the idea is (was) that if the signals are flashing you are able to exceed 125mph (obviously assuming you are a test train with the permission to) and the change from a flashing green to a steady green would be to allow a train to be down to 125mph before reaching the double yellow so that there is the time and distance to brake. Currently though the instructions are quite clear that they are to be treated as steady greens would by all drivers, except those of test trains with authority to exceed 125mph. On the AWS there is a line in the Sectional Appendix which says (not quoting directly of course!) that the AWS will give a bell for flashing and steady green aspects, but there is no further expansion so if something else may have been put together if this had gone through, how it would have worked, I could not honestly comment.
Hopefully in real life train drivers will always be paying attention to the colour of the signal, including whether it is flashing or not, rather than just relying on AWS to beep or boop. Signals allow plenty of time to gently brake before the red, if a driver did miss a steady green and found themselves doing 140mph at a double yellow they would just need to brake harder, bad for customer comfort but that extra 15mph isn't going to prevent the train from being able to stop at the potentially upcoming red.
There would be 140mph running on the ECML and probably other places already if all there was to it was paying extra attention to signals. From our perspective it seems quite simple but unfortunately that’s not how the real railway works which is why 95% of our railway is still limited to 125mph
Thanks for the responses, all. Incidentally, at certain locations on the routes where I work the signal sequence is actually: double yellow, double yellow, single yellow, red. That’s because the distance between signals doesn’t meet the standard for the line speed if you only get one double yellow (you don’t have enough braking distance to stop at the red), so you always get two. That fact isn’t publicised to Drivers, because it would be too confusing. The message is consistent - if you see a double yellow, assume the next one is single yellow - but in certain locations that can’t actually happen! I wonder whether they considered a similar arrangement for 140mph running on the ECML. It may have been simpler than introducing flashing greens.
There are locations where there are short signal sections (which is part of the driver’s route learning) so if you are doing 125mph as you’re approaching the double yellow, you need to be in or near full service especially these days where there are TPWS+++ some starting as far back as what would be the single yellow. If possible, I’d be interested to know the location (PM if you prefer). This is not something I’m familiar with nor understand why this would be needed as in these situations where is a high risk of overrunning the red, you would be doubled blocked. Double Yellow -> Yellow -> Red, steps up to single yellow on approach -> Red
TPWS is ineffective above 100mph regardless. TPWS works upto about 75mph, and a TPWS+ installation increases upto about 100. But after that, it won't do much to stop a train.
