Signalling and 140mph running

[notadriver]

? ? ? ?

I was once told by a train driver that use of more than step 2 (or approximately 50 percent of the maximum braking capacity) was not to be used during normal 'routine' braking.

 

[Old Timer]

Ah yes, understand now.

This is not a signalling rule.

Braking is based upon seeing the AWS magnet at the YY and commencing a service brake application at that point.

As a broad rule the signal section was twice the half service braking distance of a loco hauled passenger train, i. e. the train must always be able to stop from line speed within a signal section with a full service application. Thus initiating a half service application will bring you to a smooth stand at the Red from YY, whereas for example a full service will bring you to a stand at Y if applied passing YY.

As I recall a full service application reduced to brake pipe to 12.5psi

The 50% rule you quote is not the fomula used in signalling calculations but Step 2 on older units could be considered to be nearly the equivalent of service.

The HST stock had a modification such that there was a higher brake force applied to the wheels in comparison with Mk 2 and 1. This allowed the stock to brake from 125mph to a stand within the same distance as a 100 mph train operating Mk2 or Mk1 stock.

In some areas, i.e. the former Great Eastern suburban area, signals were spaced at substantially reduced distances, these being based upon EMU stopping distances because this was the only way in which the train service could operate. In consequence freight train speeds were considerably restricted.

In a slight diversion, Freightliner trains regularly exceed the signal spacing and thus were at risk of derailment if brought to a stand in certain ares. Thus it was that these trains were specially described on the signalling system and were prohibited from entering certain sections if the intermediate signal(s) were at Red until the whole section (of several signals) was clear throughout.



Edit : Braking distance calculations are slightly more complex these days.

 

[notadriver]

Thank you for that very informative post Old Timer. I've no experience of how brakes were used on older units or locomotives. Interestingly when I had a cab ride in a Javelin, the driver never used more than 50 percent of the available brake!

 

[Metroland]

Thats a hell of a junction margin !! Depends on the junction speed, distance between signals, double red protection, speed of the freight etc etc... its not as cut and dried as your example.

It's not that cut and dried no, it's an example of a long heavy freight, starting from a stand, crossing a flat junction. Say, for example, a 600 metre aggregates train travelling at an average speed of 4 meters per second. In which case it would take 150 seconds, plus the reaction time of the driver, and the time it takes to clear the junction, which could easily another 100 seconds, or just over 4 minutes.

Obviously in 4 minutes an HST can travel over 8 miles, plus the signals would need to be cleared 1 1/4-2 miles in rear to get clear greens, hence where the figure of 10 miles comes from.

An example would be a crossing move at Southall, the HST would probably get checked if it's left Slough.

An extreme example for sure, but these are the kind of things that destroy capacity and make it difficult to path high speed trains.

 

[E&W Lucas]

Does anyone know if the recommended 50 percent braking rule applies to high speed trains, or do they have to brake harder?

You've had a driving policy half explained to you.

The 3 Step brake is fitted to the 2nd generation multiple units. When introduced, drivers were taught to go straight into step 3 (full service), then progresssively ease back to step 1 as they came to a stand. It works by electrical circuits, so brake pipe pressures do not apply. Drivers are now taught to use step 2 for normal braking, and keep step 3 "in reserve", or in some companies only to use it briefly at higher speeds. It's a company policy, not a rule in the railway sense of the word.

HST's or Mk IV's are fitted with the 7 step brake, controlled by an E70 brake control unit. High speed braking is a case of "early and light" if you can. You start to brake for a station a couple of miles out, and aim to come in on one smooth application.

 

[The Planner]

An extreme example for sure, but these are the kind of things that destroy capacity and make it difficult to path high speed trains.

It wouldnt make it difficult to path the HST, we'd move the freight if we had to ! Its also why you try and keep a freight moving when crossing junctions, you only plan them to a stand if you can't do anything else.

 

[Metroland]

Quite so, but you know as well as I do freight doesn't tend to stick to timetables too well, and it's not always possible to keep things on the move.

As I said, it's an extreme example and raising train speeds when you have a very varied traffic mix destroys paths, as you know, which can mean less revenue, depending on how much additional revenue is attracted by cutting timings.

I once sat in a meeting where it was even suggested that some parts of a principal main line should be *lowered* to accommodate more trains. There are considerable areas, especially on the GWML east of Wotton Bassett junction and the WCML where pathing is very tricky simply because of the traffic mix and raising overall speed would make the situation worse.

 

[Old Timer]

....An example would be a crossing move at Southall, the HST would probably get checked if it's left Slough.

An extreme example for sure, but these are the kind of things that destroy capacity and make it difficult to path high speed trains.

Assuming the train was doing the booked Down Relief to Southall West Loop or vice versa to the Up Relief an Up train would be checked by YY at SN280 which is at the London end of Hayes & Harlington station platform.

This signal is 2838 yards from the signal protecting the movement - approx 1 & 3/8 miles

 

[Metroland]

Correct.

 

[Old Timer]

Foreign railways have worked for some years on raising the speed of freight trains closer to passenger.

Obviously some Countries benefit from a culture and support that allows them to build new lines or widen existing lines.

On a busy mixed traffic line, freight trains are only a nuisance if yoiu dont keep them running, and in my day everything was done to do this.

One way to ease the situation is to invest in more higher speed crossovers. This can be done by specifying that every new crossover on a high speed line should be a minimum of 70 mph, with exclusions to 50 where this is not practicable.

Experience further down to line in the process however indicates that none of the TOCs are prepared to pay for the additional infrastructure costs, as they see it as only favouring FOCs, and of course FOCs are hard put to show a competitive price against subsidsed road hauliers.

There is definitely a case here for ORR to step in a insist that TOCs accept rather than oppose infrastructure changes in this manner.

I know that a couple of years back, the remodelling of Wrawby Jct to allow a much higher speed towards Doncaster was cast back to the drawing board because of wrangles over who benefitted most from the junction realingment.

Interestingly enough a foreign freight only client has accepted my advice to install high speed turnouts into crossing loops as part of a bigger plan to increase line capacity without any debate. This will allow us to run crossing trains into the loop BEFORE the driver has to initiate any brake application.

We are talking about a long switch nearly (200m long) yet the operator can see the potential that so called more astute "European" operators cannot. :roll:

 

[notadriver]

You've had a driving policy half explained to you.

The 3 Step brake is fitted to the 2nd generation multiple units. When introduced, drivers were taught to go straight into step 3 (full service), then progresssively ease back to step 1 as they came to a stand. It works by electrical circuits, so brake pipe pressures do not apply. Drivers are now taught to use step 2 for normal braking, and keep step 3 "in reserve", or in some companies only to use it briefly at higher speeds. It's a company policy, not a rule in the railway sense of the word.

HST's or Mk IV's are fitted with the 7 step brake, controlled by an E70 brake control unit. High speed braking is a case of "early and light" if you can. You start to brake for a station a couple of miles out, and aim to come in on one smooth application.

Thank you E&W Lucas but you say only half of the driving policy? Which bit is missing ?

 

[E&W Lucas]

Thank you E&W Lucas but you say only half of the driving policy? Which bit is missing ?

Train driving is more than just a policy, it is a practical skill. The driver you have spoken to has tried to outline how he is expected to work in layman's terms. His explanation only refers to one type of brake system for a start.

Think of it as being like trying to describe how you walk. Unless someone has practical experience of the activity, it is going to be very difficult.

 

[Invincibles]

You mean 4-aspect signalling as found in many places on the network already:

Signal Aspects

Yes, that is sort of what I meant. I can never remember which way round the yellows are.

The point that a certain aspect should tell a driver to lower speed ready to apply the brake at the next one is the one that I was trying to make. That way it should be possible to run faster without worrying too much about braking curve as should the brakes need to be applied the train would already be checked to a lower speed.

Does not do much for signal sighting though so any system would be plagued by that problem still.

 

[driver9000]

You've had a driving policy half explained to you.

The 3 Step brake is fitted to the 2nd generation multiple units. When introduced, drivers were taught to go straight into step 3 (full service), then progresssively ease back to step 1 as they came to a stand. It works by electrical circuits, so brake pipe pressures do not apply. Drivers are now taught to use step 2 for normal braking, and keep step 3 "in reserve", or in some companies only to use it briefly at higher speeds. It's a company policy, not a rule in the railway sense of the word. [\QUOTE]

Not all companies teach 'step 2' braking. For Westcode brakes we were taught to base the braking on step 1 for tread brakes and step 2 for disc brakes, with adjustments as necessary.

 

[Zoe]

110mph sections with 2 aspect signalling are Berks and Hants west of Castle Cary

Unless something has changed recently, there are no 110 mph sections on the Berks and Hants west of Castle Cary. The maximum linspeed between Castle Cary and Cogload Junction is 100 mph.

 

[E&W Lucas]

Not all companies teach 'step 2' braking. For Westcode brakes we were taught to base the braking on step 1 for tread brakes and step 2 for disc brakes, with adjustments as necessary.

Exactly - company instructions, reflecting the different characteristics the traction used, not the sort of rigid "rules" that the OP thought existed.

 

[ainsworth74]

Does not do much for signal sighting though so any system would be plagued by that problem still.

I would say that is the main problem. A 5 aspect signalling system has been trialled (using a flashing green aspect) and as far as I know the only problem with that was that over 125mph the drivers can't sight the signals safely 100% of the time.

The only way we're going to see higher line speeds that 125mph is with in-cab signalling.

 

[notadriver]

Exactly - company instructions, reflecting the different characteristics the traction used, not the sort of rigid "rules" that the OP thought existed.

Sorry not to be rude but I didn't think they were rigid rules - simply the braking instructions for the company and for that type of traction.

 

[tbtc]

Quite so, but you know as well as I do freight doesn't tend to stick to timetables too well, and it's not always possible to keep things on the move.

As I said, it's an extreme example and raising train speeds when you have a very varied traffic mix destroys paths, as you know, which can mean less revenue, depending on how much additional revenue is attracted by cutting timings.

I once sat in a meeting where it was even suggested that some parts of a principal main line should be *lowered* to accommodate more trains. There are considerable areas, especially on the GWML east of Wotton Bassett junction and the WCML where pathing is very tricky simply because of the traffic mix and raising overall speed would make the situation worse

This is what I've argued many a time. High Speed works okay on segregated lines like HS1, but increasing the top speed on "existing" lines is a very short term move because you catch up with the slower train in front pretty quickly.

That's why I can't see the point in moving above 125 on existing railways, but am all in favour of 150 on HS2 (which seems like a contradiction to some)

 

[swt_passenger]

This is what I've argued many a time. High Speed works okay on segregated lines like HS1, but increasing the top speed on "existing" lines is a very short term move because you catch up with the slower train in front pretty quickly.

A bit like the ridiculous suggestion here a few weeks ago that SWT should bin half their normal timetable (if not more) so someone could bash an HST on rare track through Woking...

 

[RichW1]

I have to say I understand the arguments against running over 125mph on conventional lines in this country because of how increasingly cramped they are with mixed traffic speeds.

I remember when I travelled in 1990 on an HST to York and it did it in 1hr40mins exactly which says to me it was exceeding 125mph on sections? Also I wonder if it might be pointing out that all the freight that used to work the coal mines has gone now, so if freight really has come back to levels that were around then owing to container traffic I don't see why in sections they still can't be allowed to overspeed.... I have talked to several drivers who regularly managed 135mph driving HST's over sections before the strict rules came in. The railwaymen knew what they were doing and no crash has ever happened due to overspeeding and getting into stations early!

I'm also told contradictory to an earlier post that the HST's suffer much more wear on the alternators if they were allowed to overspeed in a hypothetical world which means in daily service it would be unviable anyway on service costs.

 

[gordonthemoron]

it's not restricted to the UK, I've been on a late running ICE3 between frankfurt airport & cologne which hit 329kph, they're not supposed to exceed 300kph in germany

 

[notadriver]

Regarding overspeeding - what does it say about train drivers in today's safety concious climate if they are allowed to get away with speeding? If there happened to be an incident and the driver was found to have been speeding previously, imagine the payout if lives were involved ? No railway professional would agree speeding is 'ok'!!

 

[RichW1]

You can't overspeed now anyway; systems don't let you as far as I'm aware but with regard to your point....

There's never been an incident due to overspeeding. Drivers know what the train can do, just like the WCML, drivers of the Pendolinos agree they could easily do 135mph without any danger at all, the same was true in 1980's and early 90's, the infrastructure is capable and I don't buy the argument that drivers can't react fast enough on lines when they did it just fine in the past and managed to get trains in early when railwaymen were proud of getting trains in before time. It was pride in the job and didn't endanger anyone!

I might add 125mph isn't very fast anyway; when a train goes past at 125mph it doesn't exactly blow me away with how fast it is, it just sort of glides past. It may have seemed fast in the past but if you've ever done 125mph in a car (and I have on a circuit and more) it's a reasonable speed but not enough that you can't see what's happening if you're trained to do it everyday. The only argument I can see against overspeeding or officially being able to go faster than 125mph is pathing and traffic issues due to a intensively used railway but that's all. There's a lot of excuses now that weren't there before and business has taken over meaning every piece of acceleration costs becuase of diesel or electricity used which is a shame really. Like in sport, private enterprise and railways do not make for the best railway. I remember the days when I could travel on a Sunday by train!

The Lisbon to Porto pedolinoas do 135/137 on large sections of line but then theirs are a lot quieter in terms of traffic than ours but I'm not aware of any radio based signalling there, the same with the pendolinos in northern Italy; same story.

 

[notadriver]

You can't overspeed now anyway; systems don't let you as far as I'm aware but with regard to your point....

Well you can overspeed on some types of train and there is nothing to make you stick to the actual speed limit in force. Yes permanent TPWS speed loops force you to slow down for a PSR but thereafter it is down to the driver to make sure the speed is regulated within the PSR. In other words if the limit was 60, there is nothing to stop a train doing 70. There are exceptions - those fitted with ATP or TASS.

There's never been an incident due to overspeeding. Drivers know what the train can do, just like the WCML, drivers of the Pendolinos agree they could easily do 135mph without any danger at all, the same was true in 1980's and early 90's, the infrastructure is capable and I don't buy the argument that drivers can't react fast enough on lines when they did it just fine in the past and managed to get trains in early when railwaymen were proud of getting trains in before time. It was pride in the job and didn't endanger anyone!

Never been an incident due to overspeeding? What about Maidstone East, Nuneaton or Morpeth?

I might add 125mph isn't very fast anyway; when a train goes past at 125mph it doesn't exactly blow me away with how fast it is, it just sort of glides past. It may have seemed fast in the past but if you've ever done 125mph in a car (and I have on a circuit and more) it's a reasonable speed but not enough that you can't see what's happening if you're trained to do it everyday. The only argument I can see against overspeeding or officially being able to go faster than 125mph is pathing and traffic issues due to a intensively used railway but that's all. There's a lot of excuses now that weren't there before and business has taken over meaning every piece of acceleration costs becuase of diesel or electricity used which is a shame really. Like in sport, private enterprise and railways do not make for the best railway. I remember the days when I could travel on a Sunday by train!

Isn't it more to do with being able to see the signals and the braking distance required from 125 mph? Could a train doing 140 mph stop within the same distance that a train from 125 mph can? What about adverse rail conditions?

The Lisbon to Porto pedolinoas do 135/137 on large sections of line but then theirs are a lot quieter in terms of traffic than ours but I'm not aware of any radio based signalling there, the same with the pendolinos in northern Italy; same story.

As far as I know Britain is the only railway in the EU which allows trains to run above 100 mph without any form of cab signalling and speed supervision.

 

[Peter Mugridge]

Never been an incident due to overspeeding? What about Maidstone East, Nuneaton or Morpeth?

Wasn't there one at or near Didcot as well once when a driver didn't realise until too late that he had been signalled onto a relief loop and he approached at full line speed?

I seem to recall that one of the well known railway personalities was actually on board and he realised what was about to happen moments before it did; was it O.S. Nock?

 

[sprinterguy]

Wasn't there one at or near Didcot as well once when a driver didn't realise until too late that he had been signalled onto a relief loop and he approached at full line speed?

I seem to recall that one of the well known railway personalities was actually on board and he realised what was about to happen moments before it did; was it O.S. Nock?

Yeah it was O.S. Nock.

 

[RichW1]

I thought if you in a cab of a 91 the black box records what's going on. I heard (and just heard not saying whether this is fact) that if you overspeed technology means everyone will find out and you lose your job instantly? I heard it was almost impossible to overspeed without anyone knowing now and that if they did systems would stop them anyway?! anyone enlighten me here?

I take the point about the accidents then on lines like the ones mentioned, I suppose I mean I don't remember any being an Intercity crashing because of overspeeding?! If you misread a signal, that's happened at low speed as well; I'm just not convinced given past train times on Intercity's that overspeeding on these services was a problem. Trains have slowed down from the 1980's and 1990's apart from on the WCML. With stopping distances I wasn't advocating 140mph as I know you're right and stopping from that speed in adverse weather etc would not be able to be done efficiently, I should've clarified I meant doing 130 or sometimes a touch over on clear sections like they used to getting you in early at times that was all.

Definitely had an education on in-cab signalling though; I saw no mention of this on the Lisbon line or north Italy but if that's a fact then it's a fact and I stand corrected!!! Jesus though, if it is, it just shows how little investment we've had in our signalling and what could've been achieved if we had! Still I comfort myself with this....

On the ECML and WCML major city start point to major city destination point often beats most of the main lines in Germany on the major routes i.e Berlin - Frankfurt, Berlin to Munich and Munich to Frankfurt (apart from Hamburg to Munich) even with sections of track that go faster because the rest of their network is so poor in speed terms. It's a case of Hare and the tortoise! Even when new London to Frankfurt services start, it'll take 5 hours! The distance if you get a map is the same as London to Fife area which takes a similar time with 125mph trains! Germany has the nearest geographic settlement pattern to the UK so I'd say we've pushed 125mph almost to the limit that's for sure and have done ourselves proud with the classic network!

Mind you, let's face it, even with in-cab signalling on the ECML it'd never manage anymore than 125 now because most of the line is diesel again now given most spurs aren't electrified so they'd hold up and mess up pathing with faster trains. The ECML should've been electrified in totality like the WCML.

 

[Metroland]

It's possible to overspeed except with trains fitted with ATP, or if TWPS loops are activated. Data loggers are standard these days on traction and signalling, so periodic checks can reveal overspeeding, which can result in disciplinary action.

 

[RichW1]

So are the 91's able to overspeed significantly still or is TPWS or ATP present there? If they are still able to overspeed....would any driver in his right mind ever even edge up to 130mph or is the culture and the chance of getting caught just too strict now?