GWR Hitachi IEP trains - dual mode

[oxford drinker]

Just a quick question randomly raised in the pub last night - the overhead wires run out at Didcot so trains switch from overhead power to diesel to go onwards to Swindon and Oxford. But not many Oxford bound trains stop at Didcot, so do they switch whilst moving or do they have to be stationary (ie at Reading)?

[Yertis]

Also why do they make such a horrible noise? They remind me of TIE fighters.

[rs1952]

The wires now run a lot further west than Didcot - now live as far as Bristol Parkway.

Trains for South Wales start their diesel engines there and those for Bath and Bristol, and also Gloucester and Cheltenham, switch over at Swindon.

I think that Oxford-bound trains would normally change over at Reading if taking the Didcot avoiding line, but we have drivers on here from that neck of the woods who can confirm that or otherwise.

[Pugland53]

On the down main (the line from London toward Bristol) the trains switch from electric to diesel at Moreton, just before Didcot. They then 'pan up' back to electric (at linespeed) just past Causeway level crossing near Steventon. They stay on electric until just before Bristol Parkway or Chippenham, depending on direction taken.
On the up main (the line from Bristol toward London) the trains 'pan up' to electric at Bristol Parkway station (or just after Chippenham at linespeed if coming from Temple Meads) and switch to diesel just before Causeway level crossing. If stopping at Didcot they can switch to electric in the station, if not stopping they switch to electric at linespeed at Moreton for the journey to London.

Edited by Pugland53 on Thursday 23 May 18:42

[oxford drinker]

Thanks. So they change whilst moving. Pub question answered! I will provide the answer with authority tomorrow night!

[miniman]

They were running in and out of Paddington on Diesel this evening.

[rs1952]

miniman said:

They were running in and out of Paddington on Diesel this evening.

They were last Sunday as well I noticed. I also noticed that there was an engineering occupation on the fast lines somewhere around Iver/ Langley where we crossed to the slow lines in both directions, and I presumed that that might have had something to do with it. If that work is still ongoing that could answer the query implied in your statement, or then again it might not

Nothing specific is showing up on the GWR engineering notice.

[nellystew]

Pugland53 said:

On the down main (the line from London toward Bristol) the trains switch from electric to diesel at Moreton, just before Didcot. They then 'pan up' back to electric (at linespeed) just past Causeway level crossing near Steventon. They stay on electric until just before Bristol Parkway or Chippenham, depending on direction taken.
On the up main (the line from Bristol toward London) the trains 'pan up' to electric at Bristol Parkway station (or just after Chippenham at linespeed if coming from Temple Meads) and switch to diesel just before Causeway level crossing. If stopping at Didcot they can switch to electric in the station, if not stopping they switch to electric at linespeed at Moreton for the journey to London.

Edited by Pugland53 on Thursday 23 May 18:42

What's the reason they have to switch at Didcot? Is it always going to be like this?

[ray951]

The bridge at Steventon is too low for trains to run through at speed on electric power. Network Rail put in a planing application to demolish the bridge but it was rejected by the local council. One reason given is it would cause access issues for the village while the bridge was being replaced.
Network Rail have appealed but I don't think the appeal is until September.
It is pretty disgraceful that IEPs are still running on diesel though Didcot nearly 3 years after the overhead lines went live.