Solent to Midlands Freight Study and electrification

[edwin_m]

That would mean all stock that might do Basingstoke terminators would have to actively be dual voltage, which would be expensive, wasteful, and add reliability issues.
Don’t really want to do that until you think about extending the AC to Woking some long time in the future (then it could have fast fast trains!)

Please tell us what stock in the area today isn't designed to be upgraded to dual voltage, and whether that stock will still be in service when any scheme like this might come to fruition.

 

[A0wen]

I see the usual amount of gold plating of a project is now going on above, especially as we are now sticking it on the rolling stock side again for SWR's successors - ian Walmsley in Modern Railways has had a thing or two to say about this approach.

What was the most common point of failure during the long life of the 313s on the GN? Voltage changeover at Drayton Park. What is the most common point of failure on Thameslink? Voltage changeover at Farringdon? Voltage changeover. Look how many others above are envisaging amelioration of changeover failures. To paraphrase what Gerry Fiennes might have said, "Don't put in voltage changeovers at tricky places. Don't, Don't, Don't".

But it wasn't when the electrification was designed, nor when they cut back from 4th rail to 3rd rail in the early 1970s, all of which was done properly.

Voltage changeover wasn't the only issue with the 313s - there were also issues with the Tripcock failing as well (the LU Tripcock was kept in place between Drayton Park and Moorgate) though that was mitigated by putting a tripcock check in at Finsbury Park which allowed for a failed train to be stopped there or sent to Kings X. I'm not sure a voltage change at Finsbury Park would have been viable - having said that, if WW2 hadn't intervened the Northern City Line would have had a very different use.

But let's be realistic about voltage changeovers - it happens hundreds of times a day across the network - Drayton Park alone sees at least 8 / hour for about 18 hours a day, Farringdon sees even more and then you've got it on the North London Line at Acton and West London Line as well - yet how many failures are there ?

 

[Meerkat]

Please tell us what stock in the area today isn't designed to be upgraded to dual voltage, and whether that stock will still be in service when any scheme like this might come to fruition.

“Designed to be upgraded” isn’t the same as dual voltage. It means you have to buy all the extra bits and have them fitted and tested, on ageing stock. Plus the increased failure risk and maintenance costs, for a couple of miles that a lot of them might not even be doing regularly.

 

[edwin_m]

“Designed to be upgraded” isn’t the same as dual voltage. It means you have to buy all the extra bits and have them fitted and tested, on ageing stock. Plus the increased failure risk and maintenance costs, for a couple of miles that a lot of them might not even be doing regularly.

If Crossrail 2 is ever built all the stock will be dual voltage anyway - unless the whole area ends up at 25kV.

 

[zwk500]

If Crossrail 2 is ever built all the stock will be dual voltage anyway - unless the whole area ends up at 25kV.

Crossrail 2 will be new build stock though. And we're well Off topic now

 

[a_c_skinner]

25kV AC requires (at least one of) the running rails of each track to be bonded to earth, otherwise lineside metal objects could give an electric shock, whereas DC requires the running rails to be insulated from earth, otherwise lineside metal objects could be damaged by electrolytic action.

Thanks. So actually the solution would be four rail like the tube. Just kidding.

 

[Bald Rick]

What was the most common point of failure during the long life of the 313s on the GN? Voltage changeover at Drayton Park.

The tripcocks. Not the voltage changeover.

What is the most common point of failure on Thameslink?

Assuming you mean rolling stock, it’s the DMI, not the voltage changeover.