Great Western line to be electrified - at last!

... not that I've ever used, or am ever likely to use the railway between London and south Wales, but it has always seemed strange to me that this important part of our inter-city railway infrastructure has never been electrified.

Well finally it's going to be done, at a cost of £1 billion (which will also pay for electrification of an alternative route between Liverpool and Manchester).

http://news.bbc.co.uk/1/hi/uk/8164070.stm

About time.

[injuneer]

I thought in the past the Severn tunnel posed a problem to electrification. i.e clearances for overhead wires & it's permanently soaking wet!

Originally Posted by injuneer

I thought in the past the Severn tunnel posed a problem to electrification. i.e clearances for overhead wires & it's permanently soaking wet!

They'll have to do something about that, no doubt they'll have some plans in place to stop the water from coming into the tunnel.

[frogstamper]

I'm sure somebody can tell me why, but wouldn't it be a lot easier and cheaper to lay a third live rail instead of those overhead lines?
Down here on the South coast and adjoining mainline London routes all our track is electrified this way, also its not so unsightly.

[Welshchris]

Chris r they doing this because of the new trains comining into force in 2012?
I live in swansea and always use the FGW service that runs between Swansea and London, not always as far as London, someones just as far as Cardiff.

[injuneer]

Originally Posted by frogstamper

I'm sure somebody can tell me why, but wouldn't it be a lot easier and cheaper to lay a third live rail instead of those overhead lines?
Down here on the South coast and adjoining mainline London routes all our track is electrified this way, also its not so unsightly.

I don't think 3rd rail systems (750v DC) can deliver enough power for high speed trains, Ok up to about 90 or 100 MPH which wouldn't match the current performance of the IC 125 diesels. The Thameslink trains seem to have a lot better performance under the wires (25,000 V AC) North of London than they do on 3rd rail in the South. AC power distribution is a lot more efficient than DC.

Correct, it's due to insufficient power. Overhead lines deliver 25KV, whereas in the UK third-rail systems are limited to 750V. Much more than that and there's a risk of arcing between the third rail and the nearest running rail. But 750V is nowhere near enough for an express train running at full speed.

[frogstamper]

Thanks for the answers guys, I'd always assumed it purely down to finances, obviously not.
The fastest trains down here run on the Brighton to London line, and I remember talking to a guard a few months back who told me that they very rarely run faster than eighty mph, at the time I just assumed that was because of all the curves in the track.
Having said that the Gatwick express run by Virgin may be a little faster.

Third-rail systems are actually a lot cheaper to install and maintain. I guess we'd see a far wider use of them if it weren't for the capacity issue.

Eurostar trains actually had shoes installed for third rail pickup when they began service in the UK, for use on the line between the chunnel and London. But then this wasn't going to be a big problem as they couldn't get anywhere near fulll speed on that stretch anyway. I believe these may have been removed since HS1 opened - it has overhead wires.

[BBKing]

I'm sure somebody can tell me why, but wouldn't it be a lot easier and cheaper to lay a third live rail instead of those overhead lines?

Maximum speed on third rail is 100mph, so it's not suitable for high speed rail. Apart from this there's the excessive current draw required to run 6,7,8MW electric express trains on 750V DC, which wastes power in heat and requires hefty chunks of metal to conduct it.

3rd rail is also far less safe than overhead for track workers.

Chris - the Eurostar sets have had the 3rd rail shoes removed.

[Welshchris]

these new trains i know they r gonna be faster etc, atm it takes around 3hrs and 20mins from Swansea to London Paddington, how much will these new trains shave off that?

i was told it was around 3/4 of an hour tops.