I can see that in the next 30 years that we will have the IETs▸ more being ordered for further frequency improvements. Ultimately, if you want to deliver some of the stuff in the Western Route Study then you are going to need more units.
Once electrification to Cardiff and eventually (we hope) Bristol and Oxford it would be cheaper to order some all electric IETs for those duties if a larger fleet is required.
May be quite some time before the Severn Tunnel is energised, so bi-modes will be necessary for a while.
Talking to someone who regularly travels to Bridgend from Bristol Parkway they said that in conversation with staff at
BPW» the staff are commenting that in the long run it might be cheaper to bore a second Severn Tunnel than to keep spending millions each year TRYING to maintain the present tunnel.