Cambrian Line KMH Speeds

[saismee]

Split from: https://www.railforums.co.uk/threads/examples-of-unique-level-crossings.286409
Location in question: https://maps.app.goo.gl/VZvSiHrKcN1751Yo6

No; The bottom speed on the sign - the one with the bigger number - is for passenger trains/ECS/light engine etc trains; the upper speed is for all other trains, mostly freight.

Yes, as the Cambrian uses km/h

Conflicting answers here, I'll assume that AlterEgo misunderstood that I mean one is MPH and one is KMH. I meant to ask if it is both a differential sign and a KMH sign (based on the black background with white text).

Is there a reason the Cambrian line uses KMH (and is it historic)? I'm uneducated on how train services operate in this area (well, Wales as a whole).

 

[hexagon789]

Split from: https://www.railforums.co.uk/threads/examples-of-unique-level-crossings.286409
Location in question: https://maps.app.goo.gl/VZvSiHrKcN1751Yo6


Conflicting answers here, I'll assume that AlterEgo misunderstood that I mean one is MPH and one is KMH. I meant to ask if it is both a differential sign and a KMH sign (based on the black background with white text).

Is there a reason the Cambrian line uses KMH (and is it historic)? I'm uneducated on how train services operate in this area (well, Wales as a whole).

The Cambrian was chosen as a testbed for ERTMS (ETCS Level 2) in cab signalling, it works in km/h rather than mph.

The speed restrictions on the line were converted to km/h, a 60mph limit became 95km/h for instance.

Although speeds are ordinarily displayed continuously to the driver using an in-cab display integrated with the speedometer, for occasions where the in-cab display is unavailable there are speed signs in certain locations - otherwise the default degraded working speed is only 40km/h (25mph).

 

[saismee]

The Cambrian was chosen as a testbed for ERTMS (ETCS Level 2) in cab signalling

What differences (and benefits) does ERTMS have over level 1 ETCS?

It works in km/h rather than mph.

The speed restrictions on the line were converted to km/h, a 60mph limit became 95km/h for instance.

This makes sense, I assume ETCS uses KMH because it's more common in other parts of Europe. Are the KMH speed restriction boards also in other parts of the UK with ETCS (ECML, for example)?

How does it inter-operate with other lines, does any service swap from KMH to MPH limits partway along its route?

 

[hexagon789]

What differences (and benefits) does ERTMS have over level 1 ETCS?

I understand Level 1 does spot data transmission (fixed location only); Level 2 offers continous data transmission.

This makes sense, I assume ETCS uses KMH because it's more common in other parts of Europe. Are the KMH speed restriction boards also in other parts of the UK with ETCS (ECML, for example)?

The parts of the Tyne & Wear Metro shared with Network Rail have dual km/h / mph signage as T&W uses km/h.

Not sure what the ECML South installation is like, I've not seen much detail I'm afraid.

How does it inter-operate with other lines, does any service swap from KMH to MPH limits partway along its route?

The 158s units presently used do operate non-ERTMS equipped routes/services as I'm sure the batch of 197s so fitted will equally do so.

Presently, many of the Cambrian services extend beyond the length of the route itself, some as far as Birmingham, so they will transition from metric to imperial speeds mid-journey or vice-versa.

 

[Sorcerer]

What differences (and benefits) does ERTMS have over level 1 ETCS?

ETCS is merely a part of the ERTMS wider package. But in short ETCS Level 1 is the first stage that is integrated with existing colour-light signals and balise ramps and still relies on them for movement authority, and communication is more intermittent as a result, so capacity is less than ETCS Level 2 which doesn't need lineside signals and uses radio communication for movement authorities via GSM-R (part of the ERTMS package). As well as allowing removal of the lineside signals it also allows for higher speeds, more track capacity, and if building from scratch provides more flexibility in track design.

 

[saismee]

Thank you both for the information, I've learnt a lot today.

 

[Harpo]

Presently, many of the Cambrian services extend beyond the length of the route itself, some as far as Birmingham, so they will transition from metric to imperial speeds mid-journey or vice-versa.

I believe the speedo automatically recalibrates around Sutton Bridge.

 

[hexagon789]

I believe the speedo automatically recalibrates around Sutton Bridge.

Wasn't sure if it was automatic or manual, but I can appreciate automatic would be far more ideal.

 

[godfreycomplex]

I understand Level 1 does spot data transmission (fixed location only); Level 2 offers continous data transmission.

Correct. Level 2 can be overlaid with signals or just with marker boards, as on the Cambrian.

Not sure what the ECML South installation is like, I've not seen much detail I'm afraid.

Speeds displayed in miles on there - the system works on kilometers and is translated by the train’s on board equipment into miles to display to the driver

 

[hexagon789]

Speeds displayed in miles on there - the system works on kilometers and is translated by the train’s on board equipment into miles to display to the driver

Thank you, presumably the existing limits are still used, so a 115mph limit would be translated into km/h for the ETCS then back to 115mph for display and adherence to by a driver?

(It doesn't use odd "metricated mph" like the Crossrail core for instance.)

 

[godfreycomplex]

Thank you, presumably the existing limits are still used, so a 115mph limit would be translated into km/h for the ETCS then back to 115mph for display and adherence to by a driver?

(It doesn't use odd "metricated mph" like the Crossrail core for instance.)

Correct

 

[hexagon789]

Correct

Thanks, that resolves something I've been curious about for a while but not yet seen clarified properly - there were plenty of suggestions, some given as fact actually, that the ETCS installation would be fully metric.

 

[godfreycomplex]

Thanks, that resolves something I've been curious about for a while but not yet seen clarified properly - there were plenty of suggestions, some given as fact actually, that the ETCS installation would be fully metric.

That was the way it was initially going to go, but the juice wasn’t considered worth the squeeze, so to speak

 

[tfw756rider]

Presently, many of the Cambrian services extend beyond the length of the route itself, some as far as Birmingham, so they will transition from metric to imperial speeds mid-journey or vice-versa.

Don't all the Cambrian services that extend beyond the Cambrian itself extend as far as Birmingham, with the only exception being (for example) early-terminating services to e.g. Wolverhampton if there are part-cancellations or line closures etc.?

 

[hexagon789]

Don't all the Cambrian services that extend beyond the Cambrian itself extend as far as Birmingham, with the only exception being (for example) early-terminating services to e.g. Wolverhampton if there are part-cancellations or line closures etc.?

I wasn't too sure to be honest, so limited myself to saying that some went to Birmingham - that seemed safer!

 

[Breadface]

Don't all the Cambrian services that extend beyond the Cambrian itself extend as far as Birmingham, with the only exception being (for example) early-terminating services to e.g. Wolverhampton if there are part-cancellations or line closures etc.?

You've got the extra even hour departures from Aberystwyth that go only as far as Shrewsbury.

 

[tfw756rider]

I wasn't too sure to be honest, so limited myself to saying that some went to Birmingham - that seemed safer!

Fair enough From Aberystwyth on a weekday for example, there are 5 "internal" Shrewsbury trains per day (the two earliest trains are such trains), 7 "extended" Birmingham International trains, and then 4 "internal" Machynlleth evening trains.

I think there are some trains between Machynlleth and Pwllheli that don't directly connect with the "main line" trains as well (like an hour's wait), so those of course are "internal" trains.

== Doublepost prevention - post automatically merged: 18 May 2025 ==

You've got the extra even hour departures from Aberystwyth that go only as far as Shrewsbury.

Yes, but you're misunderstanding the point, which is that there are normally no trains from Aberystwyth (for example) with destinations between Shrewsbury and Birmingham, such as Aberystwyth to Telford trains or Aberystwyth to Wolverhampton trains.

 

[Sheridan]

Fair enough From Aberystwyth on a weekday for example, there are 5 "internal" Shrewsbury trains per day (the two earliest trains are such trains), 7 "extended" Birmingham International trains, and then 4 "internal" Machynlleth evening trains.

I think there are some trains between Machynlleth and Pwllheli that don't directly connect with the "main line" trains as well (like an hour's wait), so those of course are "internal" trains.

== Doublepost prevention - post automatically merged: 18 May 2025 ==


Yes, but you're misunderstanding the point, which is that there are normally no trains from Aberystwyth (for example) with destinations between Shrewsbury and Birmingham, such as Aberystwyth to Telford trains or Aberystwyth to Wolverhampton trains.

I think even travelling as far as Shrewsbury means that they’ve gone beyond ‘the Cambrian itself’ in many people’s eyes - it begins at Sutton Bridge Junction to all intents and purposes:

 

[tfw756rider]

I think even travelling as far as Shrewsbury means that they’ve gone beyond ‘the Cambrian itself’ in many people’s eyes - it begins at Sutton Bridge Junction to all intents and purposes:

In terms of "internal" vs "extended" Cambrian Line services, the ones starting/finishing at Shrewsbury are considered "internal" because, (not counting the small section of track from Sutton Bridge Junction to Shrewsbury railway station, which I doubt many people think causes these "normal" Cambrian Line services starting/finishing at Shrewsbury to be "extended"), they don't use other "actual" lines like the Shrewsbury-Wolverhampton line and a section of West Coast Main Line, like the Cambrian Line's only actual "extended" (Birmingham) services do.

Anyway, we should probably leave it there in this thread