While I understand that only ERTMS fitted trains can go on the Cambrian, are the ERTMS fitted trains restricted on where they can go on the rest of the system because of their ERTMS kit. Or is it switched off at Shrewsbury and is, therefore, irrelevant?
Normally it remains switched on at all times, running as "level 0". Away from the Cambrian, the only real impact this has is that it limits the top speed of the train to either 90 or 75 depending on how the driver has set up the train.
ERTMS can be isolated if it's faulty, and there is an analogue speedometer fitted for this purpose, but once isolated it can only be reinstated by a fitter using a special key that drivers don't carry - so it is only carried out when necessary and when the unit won't be going on to the Cambrian.
There is also a well known issue at Wooferton. The transmitting station there is next to the Marches line and radio signals frequently interfere with ERTMS fitted 158s passing through, causing the system to fail and the emergency brakes to apply.
As a further illustration of the train equipment modifications for the Cambrian route, this illustration
from an Arriva report in 2011 shows the additional components installed to a Class 158 52xxx car for ERTMS:
View attachment 102526
(showing the car side-on and the locations of equipment, namely:
- GSM-R Data antenna & GPS on roof over the inside-end vestibule,
- Eurocabinet, European Vital Computer, fans, GSM-R rack, and Juridical Recorder Unit installed in the saloon adjacent to the inside-end vestibule,
- GSM-R Voice antenna on the roof over the outer-end vestibule,
- Driver-Machine Interface and GSM-R radio installed in the cab,
- Dopper radar installed under the cab,
- Odometry sensor installed on the bearing box of the inner axle of the outer bogie,
- Balise antenna and Balise Transmission Module installed near the inner end of the outer bogie.)
And this pair of photographs from
an RDG Guidance Note show the cabs of a Class 158 unit (at left) and a Class 97 locomotive (at right) with the ETCS Driver-Machine Interface screen retrofitted to the dashboard:
View attachment 102527
As well as the large work required in the cab, the 158s also have an entire cabinet in the saloon full of ERTMS equipment that takes up the space of 2 seats. It's definitely not portable!
For the ECTS to work the length of the train needs to be known. I don't know if this is configured automatically when the 158s couple or if the driver inputs this. So this could be an issue if you sandwich units.
There's no 6-car services west of Shrewsbury, then? I thought there may have been some as far as Machynlleth.
My only experience is with the “modern” implementation of ETCS on the GWML, and I know the Cambrian is non-standard (and that’s why it is being upgraded to standard eventually) - but train length information will be input by driver on setup or “Start of Mission” as it’s actually referred to in the system.
On the 158s, there are preset options for train formation that the driver can choose from. I can't remember how high up it goes but it's definitely at least as high as 6 car 158. There are also options for coupled to other 90mph stock, and coupled to 75mph stock; the latter option then reduces the speed limiter in level 0 from 90 to 75.
I u8nderstand that a driver has to be competent on a ETCS 158 in their own right even if the equipment is not actually in use. This came to light when some working arrangement required a Bristol GWR driver to work one. This means that all TFW 158 competent drivers other than Machynlleth and Pwllheli would require the this required knowledge. Perhaps a driver could confirm if I am correct or not please.
I believe this is indeed true. You can't drive more than 2 feet without setting up ERTMS (otherwise the emergency brakes will apply), and I'd be amazed if a driver not trained on it would be able to work out how to do it by themselves - it's a simple process to train, but it's not the most intuitive.
