3rd Rail Legislation

[Eagle]

I think it's that you can't do it for any significant length (the length between substations?).

In any case, the doubly-electrified tracks on the approach to Euston (1½ miles exactly according to the Sectional Appendix) are longer than the Snow Hill tunnel changeover (600 yards tops).

 

[D365]

Can be done for short distances, Farringdon-City Thameslink and Euston approach as mentioned (thanks for outgunning me Eagle!), but not technically viable for longer distances i.e. Basingstoke-Southampton.

 

[Class377/5]

Can be done for short distances, Farringdon-City Thameslink and Euston approach as mentioned (thanks for outgunning me Eagle!), but not technically viable for longer distances i.e. Basingstoke-Southampton.

Actually it was explained on here Farringdon to City Thameslink isn't true dual voltage. trying to remember the techibal stuff, was in the thread over the electric spine.

 

[D365]

Actually it was explained on here Farringdon to City Thameslink isn't true dual voltage. trying to remember the techibal stuff, was in the thread over the electric spine.

IIRC, once the full system has been comissioned, southbound trains will (automatically?) change from AC to DC at Farringdon. If the changeover fails, the train continues to City Thameslink, where passengers are booted out (or is it Farringdon?) and the train goes back north empty, changing tracks on the Snow Hill diamond. For northbound trains, the change will be at City Thameslink, failed changeovers will continue to Farringdon and switch to the south.

Although ideally, this will be done away with in the future. Conplicated business.

 

[AndyLandy]

I think it's that you can't do it for any significant length (the length between substations?).

In any case, the doubly-electrified tracks on the approach to Euston (1½ miles exactly according to the Sectional Appendix) are longer than the Snow Hill tunnel changeover (600 yards tops).

I believe it's possible to 'toggle' the earth, so a section can run as either AC or DC, but it can't be both at the same time. For small sections, you can get away with this. In fact, I assume there'll have to be a dual section from Southampton Central to Northam Junction, since I can't see anyone going to the expense of fitting pantographs to all the trains that run the Portsmouth and Brighton services just for that small section.

 

[Kneedown]

and is universally detested by all of us that have to use it daily on Southeastern !

Spare a thought for the unfortunates who have to rely on Sprinters for the daily commute. Give them a third rail and they'd think they were in heaven!

 

[Class377/5]

IIRC, once the full system has been comissioned, southbound trains will (automatically?) change from AC to DC at Farringdon. If the changeover fails, the train continues to City Thameslink, where passengers are booted out (or is it Farringdon?) and the train goes back north empty, changing tracks on the Snow Hill diamond. For northbound trains, the change will be at City Thameslink, failed changeovers will continue to Farringdon and switch to the south.

Although ideally, this will be done away with in the future. Conplicated business.

There's no Snow Hill diamond. There's a crossover south of City but it's DC only.

Not going to be done away with for many many years. However the current expected changeover is how you state. This is so failed northbounds can go to Smithfield and failed southbound's terminate at City and use the crossover north of City.

Automatic changeover will happen from 2018 once the new ATO is up and running.

 

[ainsworth74]

So SWT is going to need a lot of dual-voltage stock...

They already have a lot of dual-voltage stock all off the 450s and 444s are fitted for but not with equipment for working with OHLE. I believe they'd need a pantograph, transformer and TMS update and away you go.

 

[Class377/5]

They already have a lot of dual-voltage stock all off the 450s and 444s are fitted for but not with equipment for working with OHLE. I believe they'd need a pantograph, transformer and TMS update and away you go.

Indeed that's what Siemens have stated. After all the DV 350 is simply a version of the 450 so there's no reason why it can't be done.

 

[mr_jrt]

Indeed that's what Siemens have stated. After all the DV 350 is simply a version of the 450 so there's no reason why it can't be done.

..if they're that identical and if the pantographs are fitted would they be reclassified as 350s then? I'm not sure about the TOPS side of things for dual voltage units...

 

[D365]

I think 375-377 Electrostars are classified in the AC range as to keep them consistent with the 357s, despite the obvious jump from the initial Electrostar type. And before you say that 357 is completely random, have you ever noticed the gap between 456 and 458? Other (soon-to-be) dual-voltage trains based in the Southern Region will keep their 4xx classifications?

 

[W230]

Last I heard, you can't run both 3rd rail and AC along the same length of track since the earths are different (One's fixed, the other uses a floating earth? Something along those lines.)

You can but it's expensive. We were told that originally the OLE was going to continue south past City Thameslink and onto Blackfriars and that the only reason they decided not to was on a high cost for little (percieved) benefit.

 

[Kentish Paul]

Also platforms 5 & 6 at Ashford International are dual voltage. Its where the 395's change over from 25kv AC OH (HS1) to 750 DC 3rd rail to continue on the classic lines via Dover or Canterbury. The same is done at Ebbsfleet for 395's continuing onto the North Kent classic line.

 

[Bushy]

As well as the Health and Safety at Work Act 1974 and various H&S regulations (mentioned elsewhere in the context of electrical safety) there is also the IEEE Wiring Regulations (BS7671) which relate to design.

Whilst I agree with the gist of much that has been said relating to safety, I think you'll find that the scope of BS 7671 does not include railway traction power systems. I can check the scope tomorrow but the IET website states "The IET Wiring Regulations are of interest to all those concerned with the design, installation and maintenance of electric wiring IN BUILDINGS." Before 16th Edition, and adoption as a BS, they were subtitled "Regulations for the Electrical Equipment of Buildings"

Regards

Bushy

 

[AndyLandy]

You can but it's expensive. We were told that originally the OLE was going to continue south past City Thameslink and onto Blackfriars and that the only reason they decided not to was on a high cost for little (percieved) benefit.

Expensive because running dual-voltages is expensive, or expensive because running OLE through the tunnels requires lots of work?

 

[D365]

Probably the latter as the trains would still have to be dual-voltage for beyond Blackfriars - which is always more expensive [than OHLE only].