140mph

[Railsigns]

Does a flashing green still officially mean the next section is also green or better or is it treated as a standard green aspect?

Drivers of all trains, other than Class 91s authorised to exceed 125 mph, were instructed to treat a flashing green the same as a steady green. This still applies.

Pretty sure the rule book now says that it has no special meaning.

Flashing green aspects were never mentioned in the Rule Book. There's an item in the relevant Sectional Appendix.

 

[najaB]

Flashing green aspects were never mentioned in the Rule Book. There's an item in the relevant Sectional Appendix.

Sorry, it was the SA I was thinking of rather than the Rule Book - should have been clearer.

 

[QueensCurve]

In the late 80s when I assume 140mph running was first mooted on the ECML was in cab signalling even dreamt of?

Already in use then on the Paris Sud-Est Ligne à Grand Vitesse.

 

[Failed Unit]

In the late 80s when I assume 140mph running was first mooted on the ECML was in cab signalling even dreamt of? Surely if the capable rolling stock was built, then was this high speed running more than a pipe dream and was in fact a serious ambition, with the boffins at BR believing the fifth aspect would have been sufficient to provide the necessary sighting.
I suppose I'm just wondering how serious an ambition it was and if they believed it could happen with conventional signalling. Seems crazy to build 140 mph stock without sorting the infrastructure first. A failing of BR I suppose.

I wouldn't be that harsh, between Grantham and Peterborough they even had 135mph and 140mph boards on the lineside. One of them is in the national rail museum.

BR took the view that physically 140mph could easily be achieved on sections between Grantham and Peterborough, Doncaster and York and York and Northallerton were orignally planned. I am not sure why they couldn't convince the regulator about the flashing green, but I can see arguements in fog / bad weather.

May need to have a look at any accidents in the late 1980's that may have had influence on it. Clapham or Purley may have raised concerns. It was about that time automatic train protection was developed, just can't remember which accident that was as a result of.

 

[Railsigns]

As I keep pointing out whenever they are mentioned, the flashing green aspects were never going to be a satisfactory way to run trains in normal service at 140 mph, even if it had been determined that drivers could be relied on to read, interpret and respond to a lineside signal aspect at that speed. The problem is the AWS. It gives the driver a 'clear' indication at a steady green aspect, at the point where a warning indication is needed most, since that's where a train running at 140 mph has to begin braking to stop at a red signal ahead.

 

[91103eastcoast]

Was the Selby Diversion ever envisaged as a 140mph section, being a newly built railway only a few years before the 91s?

 

[Trog]

Buggered up the quotey box thingy please imagine nice smart box around the line below.
"But within 10 years the route had degraded to the point where even 125mph was not possible without almost complete renewal and upgrade."

If you mean West Coast upgrade the track relaying they prioritised was the newest track because that was the easiest to do, and all they cared about was making the stats look good by doing the most yardage. When they had finished and 125MPH tilt running came in a lot of the oldest track was still there, and there are still lengths of F27 sleepered track dating from the late 1970's out there today.

BR was working on 140MPH running both APT with super wizzo brakes, and the flashing greens of the ECML. So far as I am aware the 125MPH maximum for running without cab signalling is an arbitrary figure, chosen as that was the fastest speed being used when the limit came in. If the APT had been an operational success no doubt the limit would have been set at 140MPH, or whatever speed it was running at the time.

 

[najaB]

Was the Selby Diversion ever envisaged as a 140mph section, being a newly built railway only a few years before the 91s?

According to Wikipedia, it was designed for 125mph but allows speeds of up to 160mph.

 

[The Planner]

Is there a standard or similar that actually states that 125mph is the max? Never seen it if there is.

 

[thenorthern]

Is there a standard or similar that actually states that 125mph is the max? Never seen it if there is.

I think its a case of HM Government won't authorise a line speed increase unless in cab signaling is installed.

 

[The Planner]

But surely somewhere it is written down or is it really a case of people have said it enough times it becomes true?

 

[LNW-GW Joint]

I think its a case of HM Government won't authorise a line speed increase unless in cab signaling is installed.

Part of it is that ATP is essential for speeds over 125mph, and the delivery vehicle for that is ETCS.
Currently, the ECML hasn't got ATP, but is due to get ETCS south of Doncaster.
The WCML has TASS for anything over 110mph.
The GWML has the pilot ATP system, which will be replaced by ETCS.
ATP for high-speed lines was a public commitment after the Hidden report on the Clapham disaster (1988).

 

[QueensCurve]

Was the Selby Diversion ever envisaged as a 140mph section, being a newly built railway only a few years before the 91s?

BR material published at the time the Selby diversion was built said that the route had been designed for 140mph running.

According to Wikipedia, it was designed for 125mph but allows speeds of up to 160mph.

No idea where they got that from.
--- old post above --- --- new post below ---

May need to have a look at any accidents in the late 1980's that may have had influence on it. Clapham or Purley may have raised concerns. It was about that time automatic train protection was developed, just can't remember which accident that was as a result of.

The Hidden Inquiry into the 1988 Clapham Junction disaster was used byt the HSE as a vehicle to stamp their vision of safety on the railway and recommended that BR trial the use of ATP. The Clapham disaster itself was caused by a wrong-side signal failure and ATP had no direct relevance.

ATP was not favoured by BR because of the potential effects on performance and also the cost of installation. It was installed as a trial system on the GWML. BR also developed TPWS as their preferred alternative.

ATP failed to prevent the Southall (1997) and Labroke Grove (1999) collisions since it was isolated as allowed by the rules given that it was a trial system.

After Ladbroke Grove the political pressure for a nationwide system to prevent fatal SPADs was inescapable and then TPWS was rolled out nationwide.

 

[edwin_m]

ATP was not favoured by BR because of the potential effects on performance and also the cost of installation. It was installed as a trial system on the GWML. BR also developed TPWS as their preferred alternative.

ATP failed to prevent the Southall (1997) and Labroke Grove (1999) collisions since it was isolated as allowed by the rules given that it was a trial system.

After Ladbroke Grove the political pressure for a nationwide system to prevent fatal SPADs was inescapable and then TPWS was rolled out nationwide.

The reason ATP didn't prevent Ladbroke Grove was that the train that passed the signal at danger (the 165) wasn't ATP fitted. The HST it collided with was fitted, I'm not sure if the SPAD replaced its signal in time to trigger an ATP brake application but it was going far too fast to stop. Southall would have been prevented by ATP and probably also by AWS but both systems were isolated in the cab in use, and this was allowed by the rules at the time.

TPWS had already been developed at the time of Ladbroke Grove in 1999 and was awaiting government funding for roll-out. I was involved in the early development, jointly sponsored by BR and Railtrack, some five years before that. TPWS was predicted to avoid some 70% of the accident casualties that ATP would have prevented, and in doing so has made it virtually impossible to justify ATP on pure safety grounds. The reasons for ERTMS are primarily to do with capacity benefits and cost savings compared with conventional signalling, but it also provides ATP effectively for free, and also reduces risk to staff because of less working trackside.

 

[cjmillsnun]

BR material published at the time the Selby diversion was built said that the route had been designed for 140mph running.



No idea where they got that from.
--- old post above --- --- new post below ---


The Hidden Inquiry into the 1988 Clapham Junction disaster was used byt the HSE as a vehicle to stamp their vision of safety on the railway and recommended that BR trial the use of ATP. The Clapham disaster itself was caused by a wrong-side signal failure and ATP had no direct relevance.

ATP was not favoured by BR because of the potential effects on performance and also the cost of installation. It was installed as a trial system on the GWML. BR also developed TPWS as their preferred alternative.

Did they? Why did it take so long for it to be implemented then after Ladbroke Grove? IIRC there was a concept design but it had never been built or trialled

ATP failed to prevent the Southall (1997) and Labroke Grove (1999) collisions since it was isolated as allowed by the rules given that it was a trial system.

It was isolated at Southall, but was not fitted to the Thames Train as the trial was with INTERCITY not NSE and was passed onto the RoSCo and GWT on privatisation.

After Ladbroke Grove the political pressure for a nationwide system to prevent fatal SPADs was inescapable and then TPWS was rolled out nationwide.

TPWS was a solution on the cheap with serious shortcomings (now mainly alleviated) and it was widely blasted in the news at the time.

 

[najaB]

According to Wikipedia, it was designed for 125mph but allows speeds of up to 160mph.

No idea where they got that from.

The reference is "Intercity Express Programme, ITT Appendix C: Added Value Monetary Values, DfT, May 2008."

Edit: Googled it and it lists a possible speed of 155mph from Shaftholme Jn to Colton Jn but notes that:

In fact, much of the route shown in Annex A as being cleared for 155 mile/h was earlier cleared for 160 mile/h, but the requirement here is limited to 155 mile/h on the basis that trains are classified under EU Directives on higher speed operation as being of ‘Type 1’ if they are capable of speeds 190 - 250 km/h, and this should be taken as the categorization that applies to IEP rolling stock.

*Seems that transmanche and I were typing at the same time*

 

[transmanche]

According to Wikipedia, it was designed for 125mph but allows speeds of up to 160mph.

No idea where they got that from.

Well, 'where they got that from' (as the citation clearly states) is Appendix C of the IEP ITT. In Annex B it shows the 'Enhanced Line Speed Profile' for Kings Cross to Darlington, which lists 155mph for the section between Shaftholme Jn and Colton Jn (which I assume includes the Selby diversion).

It further notes that:

This shows an enhanced line speed, based on earlier experience of over-125 mile/h operation from tests on the ECML in the 1990s with Class 91 traction. It will be seen that substantial sections of route are capable of supporting operation at over 125 mile/h with five sections (totalling 135 miles) supporting speeds in the 140 - 155 mile/h range.

In fact, much of the route shown in Annex A as being cleared for 155 mile/h was earlier cleared for 160 mile/h, but the requirement here is limited to 155 mile/h on the basis that trains are classified under EU Directives on higher speed operation as being of ‘Type 1’ if they are capable of speeds 190 - 250 km/h, and this should be taken as the categorization that applies to IEP rolling stock.

So the Wikipedia article's assertion that:

... however research by British Rail in the 1990s indicated that the route geometry would permit up to 160 mph operation subject to the necessary overhead line equipment and signalling upgrades.

seems to me to be a fair one.

 

[QueensCurve]

The reference is "Intercity Express Programme, ITT Appendix C: Added Value Monetary Values, DfT, May 2008."

Edit: Googled it and it lists a possible speed of 155mph from Shaftholme Jn to Colton Jn but notes that:

I had no idea that a speed as high as 155mph was ever envisaged for IEP.

I have also just been rereading APT A Promise Unfulfilled by Hugh Williams.

Williams notes that APT had failed to achieve its design speed of 155mph because the braking system couldn't achieve the necessary stopping distance under conditions of poor adhesion and was therefore cleared by BR only for 125mph.

There were also problems with 2 pantograph current collection although a solution existed that was capable of 140mph running.

Moreover Williams asserts:-

By the end of the 1970s...BR had belatedly realised that 140mph APT made more technical and economic sense than one operating at 155mph.

That seems to tie in with a 140mph design speed for the Selby diversionary route.

 

[gsnedders]

Part of it is that ATP is essential for speeds over 125mph, and the delivery vehicle for that is ETCS.
Currently, the ECML hasn't got ATP, but is due to get ETCS south of Doncaster.
The WCML has TASS for anything over 110mph.
The GWML has the pilot ATP system, which will be replaced by ETCS.
ATP for high-speed lines was a public commitment after the Hidden report on the Clapham disaster (1988).

Notably, I believe we're the only country in Europe that allows speeds as high as 125mph without in-cab signalling. Most of Europe requires in-cab signalling for anything over 160km/h (99.42mph).

 

[edwin_m]

TPWS was a solution on the cheap with serious shortcomings (now mainly alleviated) and it was widely blasted in the news at the time.

Notably by Uff and Cullen, who were rather snooty about the projection of it being 70% as effective as ATP. This projection has since been borne out by actual events, and since the introduction of TPWS there hasn't been a single fatality on the national network that ATP would have prevented.

 

[notadriver]

Part of it is that ATP is essential for speeds over 125mph, and the delivery vehicle for that is ETCS.
Currently, the ECML hasn't got ATP, but is due to get ETCS south of Doncaster.
The WCML has TASS for anything over 110mph.
The GWML has the pilot ATP system, which will be replaced by ETCS.
ATP for high-speed lines was a public commitment after the Hidden report on the Clapham disaster (1988).

TASS is not an ATP system. It isn't linked to the signalling system.

 

[SpacePhoenix]

Could TASS become part of ETCS to add the ability for signallers to remotely disallow tilting as well as lowering the speed limit if needed?

 

[gsnedders]

Could TASS become part of ETCS to add the ability for signallers to remotely disallow tilting as well as lowering the speed limit if needed?

Without having spent too much time reading into the technical detail here, I believe one could use the reserved national datagram for tilt-authorisation, along with variable speed authorisation.

 

[edwin_m]

Could TASS become part of ETCS to add the ability for signallers to remotely disallow tilting as well as lowering the speed limit if needed?

TASS uses ERTMS balises so may become more integrated when ERTMS appears on the WCML. I believe ERTMS includes the facility for signallers to impose temporary speed restrictions remotely, but it probably won't include the facility to disable tilt remotely. I can see no reason why such a feature would be useful.

 

[D365]

Could TASS become part of ETCS to add the ability for signallers to remotely disallow tilting as well as lowering the speed limit if needed?

Imagine if a train was speeding through a curve, and then suddenly a command to deactivate tilt was received...

 

[SpacePhoenix]

Imagine if a train was speeding through a curve, and then suddenly a command to deactivate tilt was received...

I think they'd have the sense to have it so that any train in the middle of tilting can finish that tilt operation

 

[edwin_m]

Whatever might happen could equally happen today if a fault was detected in the tilt mechanism and it reverted to non-tilt mode.

 

[TheKnightWho]

TASS uses ERTMS balises so may become more integrated when ERTMS appears on the WCML. I believe ERTMS includes the facility for signallers to impose temporary speed restrictions remotely, but it probably won't include the facility to disable tilt remotely. I can see no reason why such a feature would be useful.

Does this mean we may see it introduced on more lines in the future, when ERTMS is more commonplace?

 

[SpacePhoenix]

When ERTMS eventually gets installed on the SWML (I'd assume not within the next decade), would west of Southampton Central benefit much if trains could tilt?

 

[QueensCurve]

Does this mean we may see it introduced on more lines in the future, when ERTMS is more commonplace?

If I understand it correctly, the purpose of TASS is to allow the differential speed limits implied by tilt. Likewise an earlier system C-APT was used to advise the driver of the APT-P sets of the higher speed they were allowed to use when tilting.