I just dont understand why they cant fit a couple of class 150s or 153s or even 175s with ERMTS? Is it more complex than this?
ETCS (the bit of ERTMS in the cab) was a major task for the Cambrian project (paid for by NR's development arm, so free to ATW).
It was one of the troublesome areas - small 158 cab, old electrics and control systems etc).
158s were never designed for such fitment.
You would have similar difficulties with 150/153s with their small cabs, and there is no fairy godmother to pay for it.
175s, as a modern European train design, should be easier, but again there is no policy to fit them yet.
They will need to be fitted once ERTMS is rolled out further, but that might be another decade or so.
And you would have to do the whole fleet.
Network Rail is supposed to pay for the "first in class" fitment and testing of ETCS for each type of train, with the TOCs paying for roll out across the class.
They are still wrestling with what that means on the ECML South and GW main lines, the first to be fitted around 2020.
So the Cambrian is stuck in the future, so to speak.
I don't think the problem is shortage of ETCS-fitted 158s, it's the lack of any other stock to back-fill other services to allow more of the 158 fleet to stay on the Cambrian.
