Vivarail D Trains now a possibility for South Wales Valley Lines?

[whole diary]

[anthony215]

Seen in the South Wales Echo newspaper yesterday:

http://www.walesonline.co.uk/news/local-news/piccadilly-circus-pontypridd-could-london-9319837

Heard rumours about this back in February and thought it was a joke however it does seem like a possibility. I wont complain if they are used on the core valley lines network to increase capacity and free up dmu's for use elsewhere by ATW^▸ (Arriva Trains Wales (former Train Operating Company)) such as much needed  capacity improvements on  the Ebbw Vale branch and plugging long gaps between services to Gloucester/Cheltenham as well as increasing the swanline service to Hourly.

[Timmer]

From what I've read about the converted D stock plan, I think this could be a decent quality train to increase capacity and replace Pacers. Looking forward to seeing the finished article.

[grahame]

From what I've read about the converted D stock plan, I think this could be a decent quality train to increase capacity and replace Pacers. Looking forward to seeing the finished article.

It could well be a place where they fit well.     The newspaper needs to brush up on its geography though - "From Picadilly Circus to Pontypridd" ... I don't think so; they're not getting deep level tube stock.    Or is that phase 2?

[Rhydgaled]

^One of the benefits is that because the trains don^t require going back to the depot for maintenance, they could be put on the branch lines and maintained there,^ she said. ^You^re not taking trains off the line for routine maintenance.^

Not sure how that works, or if it could work. But if so, it would seem a useful solution for the Conwy valley line given that it is remote from any other route that doesn't require 90mph stock. Wrexham-Bidston could be an interesting possibility too particularly if they can retain 3rd rail capability and hence extend the service into Liverpool. I wonder if you could also put on a Tenby - Carmarthen shuttle on summer Saturdays to provide an hourly service on that section and ease the presure on the Pacers and 150 which work the Pembroke-Swansea services (Carmarthen - Whitland does have over 10 miles of 75mph linespeed, but alot of services seem to be timed for 17-20 minutes over that section at present despite other schedules suggesting it can be done in 15 minutes).

I am however concerned about whether it is possible to turn metro-stock with 4 doors per side on each carriage into something suitable for Welsh scenic lines line the Conwy. They would probably be ok on the ValleyLines, but with electrification due (by 2025 at the latest), would Vivarail get enough lease fees to pay for the refurb?

[John R]

particularly if they can retain 3rd rail capability

There hasn't been a suggestion that option is being considered, and it would be unrealistic to incur all the costs involved (and weight, thus reducing performance of the diesel option) in maintaining a second source of propulsion just for a relatively short hop on a single route. And of course Underground stock is fourth rail, so some modification, either of the stock or the track, would be required.

[paul7575]

... And of course Underground stock is fourth rail, so some modification, either of the stock or the track, would be required.

Converting 'fourth rail return' to current return via running wheels is definitely not trivial.  Just because you cannot really see anything obvious on a typical third rail EMU^▸ (Electric Multiple Unit) doesn't mean it isn't quite different.  Basically you have to distribute the return current to many wheels (to reduce the current per wheel), and you cannot allow current to flow through the wheel bearings, so if you look closely you'll see a brush box on the outboard end of many of the axles which transfers the current to the wheels while bypassing the bearings.

(The third rail shoe has a much larger surface area than the wheel/rail contact area, so as to reduce the resistance to a similar value you need significantly more contact points.)

In extremis it could require new bogies - and IIRC^▸ ('if I recall/remember/read correctly') one of the key features of the conversion is that the existing bogies are retained.

On a shared LU/NR^» (Network Rail - home page) route the LU stock still uses the fourth rail normally, but it that rail is electrically tied to the running rails and the LU stock sees the 650 V DC^▸ (Direct Current) on the positive shoe gear, and 0 V DC on the fourth rail shoe.   

Paul