Signal Sighting for 140mph a Myth?

[RichW1]

Ok, so I've been looking at some youtube footage of East Coast Main Line and it seems to me the drivers have plenty of viewing time to see the signal aspect; doesn't exactly 'flash past'! This leads me to wonder if the whole reason given for no 140mph running (in sections) is based on some oddity that has no truth in it. I know the difference between 125 and 140 as I've done it many times on car race circuits and I have no doubt those signals as placed would still be viewable even by the eyes of the most conservative drivers!

Before the flashing green is mentioned, I get about the flash aspect of it relating to being seen (not that I agree) but no-one said it had to be a flashing green as opposed to anything else in colour or aspect but that wasn't the reason given. On the West Coast too this is the case with plenty of time to see the signals. Reason stated is the signal sighting issues with 140mph running. Fact is, I see no 'sighting issues'. Is there something relating to business and politics with this for reasons I don't know because it seems perfectly viable to me and there are plenty of long enough sections where nothing conflicts on the ECML and WCML fasts where it could be achieved easily.

 

[rail-britain]

Mentioned previously, but the issue was bascially during poor visibilty (fog and snow) and drivers eye blinking time
As a result it was found to be possible the driver could miss a signal, therefore at 140mph the next one they may see would be double yellow instead of solid green

 

[Wyvern]

Even if the driver could react in time, could the train stop reliably under adverse railhead conditions?

 

[The Planner]

The southern end of the WCML is fairly twisty aswell so Id expect bends play a large part in the signal sighting, you would have some sort of flashing banner repeater all over the place. I know very little about the process but the RGS stuff is fairly in-depth with plenty of considerations. RGS Signal sighting

 

[notadriver]

Don't forget Britain is the only country that allows trains to run at more than 100 mph without any form of in cab signalling or speed supervision ..

 

[PinzaC55]

There may have been issues with the effect of the heavy rolling stock at +125 MPH on the track. I used to work the test trains from the Cross with the 91's and the 89 and apparently the reason why the 89 was discontinued was the effect of the Co-Co bogies on the track at 125 MPH.

 

[gordonthemoron]

haven't HSTs done about 150mph on both ECML & GWML on some speed trials?

 

[sprinterguy]

haven't HSTs done about 150mph on both ECML & GWML on some speed trials?

A press run for the launch of the new Tyne-Tees Pullman in 1985 using a shortened 2+5 HST set reached 144mph on the York-Darlington racing stretch, which was later bettered by a set which topped out at 148mph on Stoke Bank in 1987. I’m sure the prototype HST managed 143mph somewhere as well. Both the APT-P and an IC225 (91010 I think) have reached 162mph: The former with a form of in-cab signalling and the latter using the flashing green aspects around Stoke Bank. The speed record for an IC225 carrying passengers was set by 91031 in 1994, which reached 154mph on the descent of Stoke bank, once again making use of the flashing green aspects, during a press run on a shortened five carriage mark 4 rake.

However it must be noted that these runs were under exceptional circumstances, usually with shortened train formations and with special operating arrangements ensuring that these trains had a clear run of several miles. Such feats could never be repeated in regular, day to day service.

 

[RichW1]

Mentioned previously, but the issue was bascially during poor visibilty (fog and snow) and drivers eye blinking time
As a result it was found to be possible the driver could miss a signal, therefore at 140mph the next one they may see would be double yellow instead of solid green

Wouldn't a solid aspect which is a new colour solve this problem quite cheaply anyone?! Just seems to me that if the repeater is the problem, then just replace the flashing green with a new colour that's solid when the following signal is green.

By the way, nice reminder there Srinterguy!

 

[gordonthemoron]

rather than fiddle around with signals in a heath-robinson style, i.e. like most things in the UK, it'd be better to get in-cab signalling

 

[WestCoast]

rather than fiddle around with signals in a heath-robinson style, i.e. like most things in the UK, it'd be better to get in-cab signalling

I definitely agree with that!

 

[notadriver]

We are getting ERTMS (in cab signalling). It's a definite.

 

[RichW1]

Is it? I though Network Rail is struggling with an implementation plan is it not?

Which brings me to GWML - If it is to actually happen at level 2, will the GWML get it following electrification/during the works? I'm not sure what the ETCS policy is anymore on the major main lines.

 

[ainsworth74]

Is it? I though Network Rail is struggling with an implementation plan is it not?

No it is definitely happening, the exact timings are still subject to some flex but the GWML, ECML, WCML and CTRL are all due to receive ERTMS over the next 10-20 years. Other lines are supposed to get it as well including the BML, SWML, MML and GEML. Most of the infrastructure work is due to be carried out in the 2020s with work on all lines being completed in the mid 2030s.

 

[Jordeh]

So when the GWML gets ERMTS along with the IEP, will 140mph running be permitted?

 

[swt_passenger]

So when the GWML gets ERMTS along with the IEP, will 140mph running be permitted?

Not necessarily - unless all traffic is capable of the higher speed, a 140 mph train just catches the one in front sooner. So it might be OK on the four track sections only - that's assuming the IEP stock is actually capable of 140 mph.

 

[ainsworth74]

that's assuming the IEP stock is actually capable of 140 mph.

I was wondering that, does the IEP specification even include provision for 140mph running?

 

[Anonywave]

No it is definitely happening, the exact timings are still subject to some flex but the GWML, ECML, WCML and CTRL are all due to receive ERTMS ...

Huh? You mean HS1? I thought that already had it. :-?

I was wondering that, does the IEP specification even include provision for 140mph running?

I was under the impression that Hitachi had said that they could achieve that speed with 'minor modifications'.

 

[ainsworth74]

Huh? You mean HS1? I thought that already had it.

It has signalling systems based on the French systems (TVM-430 and KVB), so whilst it has in-cab signalling it does not have an implementation of ERTMS.

 

[swt_passenger]

I was under the impression that Hitachi had said that they could achieve that speed with 'minor modifications'.

Almost certainly be a simple download from the internet by then...

 

[moggie]

Not a signal sighting expert as such but have lots to do with their output. As I recall (correct me if I'm wrong) the minimum requirement for uninterrupted sighting of signals is 8.5 secs at maximum linespeed.

Interrupted sighting requires additional time to be added depending on the degree of interruption. Typically this will be due to curvature where lineside structures (e.g. OLE stanchions on a LH curve) form a solid barrier to the line of sight or where adjacent trains /structures (RH curve) could block direct sighting. More physical structures will obviously present obstruction. Gradient can also be a factor where signals can be obstructed by overhead catenery or overbridges over the sort of distances required. Additionally time for assimilation is required if the signal profile is classified as complex - e;g. carries route indicators and If I recall flashing aspects.

In summary therefore at 125 mph sighting distance can often require circa 600m which as has been pointed out on sections with significant curvature can be very difficult to achieve while maintaining acceptable spacing to signals forward and aft.

Therefore cab signalling aka ERTMS is clearly the way forward if higher linespeeds are the future goal but imho ERTMS in the UK has someway to go in the development / application before it becomes widespread on UK mainline. That ignores the commercial implications to operators who do not NEED cab signalling per se'. We shall see in time.

 

[notadriver]

Ok, so I've been looking at some youtube footage of East Coast Main Line and it seems to me the drivers have plenty of viewing time to see the signal aspect; doesn't exactly 'flash past'! This leads me to wonder if the whole reason given for no 140mph running (in sections) is based on some oddity that has no truth in it. I know the difference between 125 and 140 as I've done it many times on car race circuits and I have no doubt those signals as placed would still be viewable even by the eyes of the most conservative drivers!

Just out of curiosity how much driving time do you have at those sorts of speeds? Most (UK) motorists will be lucky to exceed 100 mph and even if they do I hazard a guess it won't be for long.

 

[Captain Chaos]

What are the implications for the Guard with regards to in-cab signalling? With no signals to sight on the platform how does the guard know when the train is ready to proceed? Is it a case of driver contacting guard giving permission to commence station duties? If this is the case would it not be possible to put in place a small screen displaying the 'in-cab signal' on the guards screen? Doesn't this make the guard more or less a spare part? Being a guard myself I hope that this will not be seen as a way of making more trains DOO (although on the routes work the max speed at any point is 75 mph so probably not too much to fear about).

 

[ainsworth74]

Surely there would just be an equivalent of an 'Off' indicator on stations for the use of dispatch staff and guards?

 

[Crossover]

Wouldn't a solid aspect which is a new colour solve this problem quite cheaply anyone?! Just seems to me that if the repeater is the problem, then just replace the flashing green with a new colour that's solid when the following signal is green.

I think this has been mentioned elsewhere but the problem is likeness to other colours. e.g. blue has hints of green in it and so could be mistaken.

I believe this also has application on the roads where red/amber/green are of a particular contrast where none contain hues of any of the other colours.

Of course, you could use something like brown which is different, but it would probably be too dark

 

[ainsworth74]

One thing that occurs to me, if it was as easy to fix as installing a solid fifth aspect to the signals rather than using a flashing green surely BR would have given it a go? They must have had a good reason to not bother seeing as they spent all this money on IC225s that then couldn't operate at their designed speed. The people that BR employed to do testing and trails like this weren't idiots so you have to think that they probably thought of this themselves and ruled it out for a good reason.

 

[mumrar]

A total side issue from the signalling aspect (pun intended). I wonder what the EC Class 91 performance figures would be like if they were doing 140mph where permitted in daily service? They'd sure take a drop. Also, would the performance dent of the 9th mk3 on EC HSTs be no longer viable as they'd be in the way a lot more? Just food for thought.

 

[ainsworth74]

Actually that's quite a good point mumrar, one of the main problems on the southern (KGX-PBO) and middle portions (GRA-NCL) is the interaction of 125mph expresses with local or inter-regional services (top speed probaly 100mph or less) and with frieght services as well. One of the reasons that the ECML struggles for capacity is trying to fit all this together in some sort of coherent structure. Imagine throwing in another group of trains all running at 140mph, the impact on available paths would surely be pretty severe.

 

[The Barlow Boy]

I think this has been mentioned elsewhere but the problem is likeness to other colours. e.g. blue has hints of green in it and so could be mistaken.

I believe this also has application on the roads where red/amber/green are of a particular contrast where none contain hues of any of the other colours.

Of course, you could use something like brown which is different, but it would probably be too dark

The Norwegians seem to manage with purple.
--- old post above --- --- new post below ---

What are the implications for the Guard with regards to in-cab signalling? With no signals to sight on the platform how does the guard know when the train is ready to proceed? Is it a case of driver contacting guard giving permission to commence station duties? If this is the case would it not be possible to put in place a small screen displaying the 'in-cab signal' on the guards screen? Doesn't this make the guard more or less a spare part? Being a guard myself I hope that this will not be seen as a way of making more trains DOO (although on the routes work the max speed at any point is 75 mph so probably not too much to fear about).

There's a fixed signal at each station for starting the train. If you ever travel on the Victoria line tube which is automatic you'll see that there is a colour light signal at each platform so the operator can give the train the start signal and know that the train will start away.

 

[The Planner]

There's a fixed signal at each station for starting the train.

I don't think thats the case on the Cambrian at all, Im not aware of any lineside signals along there anymore.