Rule on in-cab signalling for 140mph - just UK?

[Wapps]

Hi,

Does anyone know if the rule preventing 140mph running in the UK without in cab signalling is a unique UK rule?

I presume there’s no EU regulation on this and thus it’s a UK rule. If it’s a UK rule, is the UK unique in this or do other countries run above 125mph without in-cab signalling? If so, I presume those countries don’t have safety issues, so why the difference in the UK?

I thought tests in the 80s with a flashing green signal had made 140mph possible till H&S said no.

Thanks

 

[rebmcr]

SNCF developed in-cab signalling for their TGV project, so it's not a unique nor new concept. I can't recall any high speed lines on the continent without it in some form.

The 140mph ECML tests showed that the length of time for which a signal would be visible at that speed was too short for drivers to reliably see, process, and understand. I believe the minimum at 125mph (used to decide where signals are placed around bends and bridges) is 8.5 seconds.

 

[AlexNL]

France has trains running at speeds of up to 220 km/h (137mph) with lights on sticks and KVB train protection.

Norway's Gardermoen Railway sees trains running at speeds of up to 210 km/h using EBICAB 700 and, as far as I know, colour light signals.

 

[James James]

Switzerland requires ETCS for speeds over 160km/h. Not sure why exactly, but their network tends to be quite busy so perhaps that's why they have lower limits.

 

[James James]

Norway's Gardermoen Railway sees trains running at speeds of up to 210 km/h using EBICAB 700 and, as far as I know, colour light signals.

EBICAB does seem to provide in-cab signals/waypoints/etc:

https://www.bombardier.com/content/dam/Websites/bombardiercom/supporting-documents/Sustainability/Reports/BT/Bombardier-Transportation-EPD-EBI-Cab-2000-en.pdf

Edit: just noticed that doc is for ebicab 2000, but even the docs on ebicab 700 suggest signalling data is transmitted - and this video shows in-cab data on an Ebicab 700 route:

 

[Taunton]

The USA requires cab signals for passenger trains over 79mph, and has done so since 1947, the standard system having been developed there in the 1920s. https://en.wikipedia.org/wiki/Pulse_code_cab_signaling

 

[Senex]

Germany has required cab signalling (LZB, now ETCS) for many years for running at above 160 km/h. Additional safety measures for the general public are required for speeds of above 200 km/h on the historic network (so far applicable only on the Berlin-Hamburg line).

 

[Wapps]

Thanks for the responses. To what extent could we not rely on ATP for protection against missing a flashing green?

 

[Tio Terry]

Suggest you read the CCS Technical Specification for Interoperability.

 

[Taunton]

As the USA has had cab signals for the past CENTURY, the original Union Switch & Signal Corp system having been progressively enhanced as time has gone along for yet higher speeds well above 125mph, all the subsequent European approaches just seem a "Not Invented Here" attitude. The most efficient thing to do, honestly, would have been to send away for the Union Switch catalogue. Which is what Ireland did.

All reminiscent of how the GWR came up with ATC (which Churchward offered to other railways without paying any royalties as he didn't think that appropriate for a safety system), meanwhile 50 years later the rest of the UK industry was still shilly-shally-ing about not fitting AWS until a whole series of ATC-preventable major accidents in the 1950s forced their hand.

 

[squash1993]

Hi all,

Long time lurker here but to answer the original question: the 140mph in Cab Signalling requirement is a UK requirement. This requirement was put in place before European Train Control System was created and before the Command, Control and Signalling (CCS) Technical Specification for Interoperability (TSI).

The requirement was introduced after the flashing green experiments on the East Coast Mainline provided feedback from the drivers. This was at the time the original (1990s) West Coast Route Modernisation was in development and as part this recognition that Sighting Signals at 140mph on the twisty railway there, flashing aspects would be challenging. This is when you consider that if you are trying to spot a signal some 500m down the track for a minimum of 8 seconds (modern standards - it wasn't always so 'generous') that an aspect not being present to spot for any amount of time is somewhat detrimental.

thanks

Squash

 

[SHD]

Other railways than Ireland’s adopted in-cab signaling devices based on or inspired by the American pulse code cab signaling - notably Italy (RS4, SCMT) and the former Soviet Union (ALSN and its successors).

 

[ainsworth74]

I must admit I was always under the impression that we were something of an outlier in allowing considerable amounts of running over 100mph and certainly at 125mph without in cab signalling!

 

[Taunton]

I must admit I was always under the impression that we were something of an outlier in allowing considerable amounts of running over 100mph and certainly at 125mph without in cab signalling!

There seems a longstanding history of turning backs on this. The Southern Region bargepoled away AWS for a long period, on the grounds that around London trains might spend long stretches on double/single yellows. This was used to justify not installing any AWS at all, anywhere on the region.

The Southern Region themselves then, in the 1970s, came up with their own enhancement of AWS, called SRAWS (Signal repeating AWS), which I always thought looked a really worthwhile advance. It overcame some of their prior concerns, also offered a constant in-cab signal display, and was compatible with conventional AWS traction. This was 50 years ago. Having got their demonstrator working (it was on the Up line between Bournemouth and Southampton, and in the London-end cabs of the 4-REPs), they got an instruction from BR HQ to abandon it.

 

[ainsworth74]

There seems a longstanding history of turning backs on this. The Southern Region bargepoled away AWS for a long period, on the grounds that around London trains might spend long stretches on double/single yellows. This was used to justify not installing any AWS at all, anywhere on the region.

The Southern Region themselves then, in the 1970s, came up with their own enhancement of AWS, called SRAWS (Signal repeating AWS), which I always thought looked a really worthwhile advance. It overcame some of their prior concerns, also offered a constant in-cab signal display, and was compatible with conventional AWS traction. This was 50 years ago. Having got their demonstrator working (it was on the Up line between Bournemouth and Southampton, and in the London-end cabs of the 4-REPs), they got an instruction from BR HQ to abandon it.

Yes that rings a bell actually. Did it feature in one of those BFI transport films? Shame it was quashed. It would perhaps be an interesting "what if" thought experiment!

 

[MarkyT]

Yes that rings a bell actually...

Or sounds a buzzer. I'll get my coat!

 

[MarkyT]

It would perhaps be an interesting "what if" thought experiment!

From this page, for reference: https://www.wbsframe.mste.co.uk/public/Surbiton_Panel.html

Southern Region/Signal Repeating AWS (SRAWS)
Originally called "Southern Region AWS", its name was later changed to "Signal Repeating AWS". The SRAWS system repeated the next signal's aspect (and displayed a reminder of the previous signal's aspect) on an indication inside the cab. Any aspect other than green had to be acknowledged by the driver pressing the correct button that corresponded to the indication on display. If the driver did not acknowledge the indication, or the wrong button was pressed, an automatic brake application was initiated. The risk of error from subconscious cancellation was therefore greatly diminished.

Above: SR AWS Cab setup. Development of SR-AWS, with signal past indications on left and signal approach indications on right. Note the km/h only calibrated speedometer.

During 1971 an experimental form of cab signalling (SRAWS - Signal Repeating AWS) which was being trialled in the up-direction between Byfleet [it may have been Woking] and Raynes Park (as well as in the New Forest area). The cab layout showed the driver the aspect of the next signal and the one that the train had just passed. Its used a coax aerial loop figure of eight in the track with a frequency module in the signal location to pass a radio frequency code to the train depending on the signal aspect. Development of SRAWS ended in 1975 when the British Railways Board dictated that the Southern Region should equip its lines with standard BR AWS.

 

[w1bbl3]

Thanks for the responses. To what extent could we not rely on ATP for protection against missing a flashing green?

GWML ATP has the capability to rely line-side signals to the cab and of course speeds, very roughly the system functionality level is similar to a modern ETCS level 1 implementation in that communication is intermittent at only balise or loop locations. In a different world maybe BR or later railtrack would have found the budget for national deployment of the system, the original GWML pilot had been to test the feasibility of doing so.

 

[Taunton]

GWML ATP has the capability to rely line-side signals to the cab and of course speeds, very roughly the system functionality level is similar to a modern ETCS level 1 implementation in that communication is intermittent at only balise or loop locations. In a different world maybe BR or later railtrack would have found the budget for national deployment of the system, the original GWML pilot had been to test the feasibility of doing so.

What a mess-about. The 100-year old American USS system did all this by coding the track circuits and tying each of these to the signalling, giving continuous display. It even was installed on multiple generations of USA steam locomotives.

 

[MarkyT]

What a mess-about. The 100-year old American USS system did all this by coding the track circuits and tying each of these to the signalling, giving continuous display. It even was installed on multiple generations of USA steam locomotives.

Not quite as continuous as you may think. Track circuit code systems can only transmit a valid code to a train in the short time the receiver aerial is over the track circuit ahead before the first axle of the train shorts it out, attenuating the signal. The aerial has to be sufficiently far ahead such that the latency of the onboard equipment doesn't prevent it successfully decoding the information, to be stored and interpreted, before that attenuation occurs. The code thus interpreted is used throughout the section without further update until the next track circuit is encountered. From an information point of view that is no different to an intermittent system that passes a code through inductive transponders at fixed positions. Truly continuous near field systems must use a separate track loop antenna having no electrical commonality with the rails, or wider field radio infrastructure.

 

[LOL The Irony]

Did it feature in one of those BFI transport films?

Indeed it did.

The Southern Region themselves then, in the 1970s, came up with their own enhancement of AWS, called SRAWS (Signal repeating AWS), which I always thought looked a really worthwhile advance. It overcame some of their prior concerns, also offered a constant in-cab signal display, and was compatible with conventional AWS traction. This was 50 years ago. Having got their demonstrator working (it was on the Up line between Bournemouth and Southampton, and in the London-end cabs of the 4-REPs), they got an instruction from BR HQ to abandon it.

I want to know what 222 Marylebone Road were thinking. We could've had in cab signalling but we don't have any outside of what is essentially a trial in Wales.

 

[MisterT]

Not quite as continuous as you may think. Track circuit code systems can only transmit a valid code to a train in the short time the receiver aerial is over the track circuit ahead before the first axle of the train shorts it out, attenuating the signal. The aerial has to be sufficiently far ahead such that the latency of the onboard equipment doesn't prevent it successfully decoding the information, to be stored and interpreted, before that attenuation occurs. The code thus interpreted is used throughout the section without further update until the next track circuit is encountered. From an information point of view that is no different to an intermittent system that passes a code through inductive transponders at fixed positions. Truly continuous near field systems must use a separate track loop antenna having no electrical commonality with the rails, or wider field radio infrastructure.

I might be misunderstanding your post, but the Dutch ATB system, which is based on the American system, is actually fully continuous. The track circuit codes are sent out from the track circuit ahead, which means that, while the wheels are short-circuitting the track circuit, the code is actually still there because it is picked up by the equipment that is installed in front of the first wheelset. As soon as the code drops (even only for a few seconds), the in-cab system automatically drops to the most restricted mode.

 

[Taunton]

I want to know what 222 Marylebone Road were thinking.

Probably thinking "Not Invented Here".

I might be misunderstanding your post, but the Dutch ATB system, which is based on the American system, is actually fully continuous. The track circuit codes are sent out from the track circuit ahead, which means that, while the wheels are short-circuiting the track circuit, the code is actually still there because it is picked up by the equipment that is installed in front of the first wheelset.

The code can be transmitted from either ahead or behind the train. Bear in mind that much of the US main line rail network is single track, and on their double track is commonly signalled bi-directional, used extensively for overtaking.

For how they do it, you will have to ask a Union Switch engineer. Or one from Irish Rail.

 

[Peter Kelford]

France has trains running at speeds of up to 220 km/h (137mph) with lights on sticks and KVB train protection.

KVB is significantly more advanced than the basic TPWS setup.

 

[Peter Kelford]

I must admit I was always under the impression that we were something of an outlier in allowing considerable amounts of running over 100mph and certainly at 125mph without in cab signalling!

We somewhat are with most other countries' technology being somewhat more advanced and where speeds require it, a willingness to install cab signalling.