Great Western Main Line electrification - ongoing discussion

[whole diary]

[Incider]

If a train takes an un-wired turnout with pantograph up, does anything bad happen, anyway? 

Is an IET^▸ (Intercity Express Train) clever enough to know whether there's a catenary wire above it?

Its not clever enough currently.  A feature called APCo (Automatic Power Changeover) is fitted to the train which will automatically change to diesel using track balises, but it is not currently working.  Running out of catenary would mean there is nothing to stop the pantograph from raising to its fullest extent.  Expect it to be removed from the train when it gets to the next overbridge!

Not true, ADD^▸ (Automatic Dropping Device) will drop the pan.

[IndustryInsider]

I stand corrected. 

[Sassafras]

 As I've said before, being an 'old Southern' man, the unpopular
 3rd rail did seem a lot less complicated.

[grahame]

As I've said before, being an 'old Southern' man, the unpopular
 3rd rail did seem a lot less complicated.

Not said here before - that's your first post - welcome to the forum!   

Also as an immigrant from third rail land, I really do look and wonder at all this string!

[YouKnowNothing]

Isn’t it to do with the power supply requirements? I.e. the the long length of the route would have required additional transformers every X miles instead of every Y miles?

As I've said before, being an 'old Southern' man, the unpopular
 3rd rail did seem a lot less complicated.

Not said here before - that's your first post - welcome to the forum!   

Also as an immigrant from third rail land, I really do look and wonder at all this string!

[IndustryInsider]

You don't get the same performance from 3rd Rail either - 108mph is the world record.  And added safety risks of course.

[Electric train]

As I've said before, being an 'old Southern' man, the unpopular
 3rd rail did seem a lot less complicated.

Its not unknown for units to get "gapped" either through units operating over routes where a full gapping survey has not been done or for example at Wokingham a unit get the wrong road and heads off to Guildford and runs out of juice rail.

You don't get the same performance from 3rd Rail either - 108mph is the world record.  And added safety risks of course.

This is true, also to get the higher performace the "nominal" Voltage is closer to 800V than it is to 750V.  But current collection is the main problem the anount of down force and surface area of the shoe either means lots of shoes or ones that get worn out quickly.  Power supply verses the number of trains becomes an issue meaning a substation ever 4 miles intead of every 10 for an AT 25kV system

[grahame]

You don't get the same performance from 3rd Rail either - 108mph is the world record.  And added safety risks of course.

For some places / services, 90 m.p.h. with good acceleration makes sense ... getting away from GW^▸ (Great Western) main line, but infill on Wokingham - Reigate would make senses to me ... and I don't see in excess of 90 m.p.h. being needed at Cowden or Three Oaks and Guestling!     Happy to have third rail up from Southampton area to Wiltshire and taking it to Bristol; I doubt the good folks of Bath would complain about it being unsightly.

[JontyMort]

You don't get the same performance from 3rd Rail either - 108mph is the world record.  And added safety risks of course.

For some places / services, 90 m.p.h. with good acceleration makes sense ... getting away from GW^▸ (Great Western) main line, but infill on Wokingham - Reigate would make senses to me ... and I don't see in excess of 90 m.p.h. being needed at Cowden or Three Oaks and Guestling!     Happy to have third rail up from Southampton area to Wiltshire and taking it to Bristol; I doubt the good folks of Bath would complain about it being unsightly.

I suppose they might get away with Salisbury on the grounds that Totton/Eastleigh-Romsey-Worting Junction via the Laverstock Curve** was "infill" but even then Salisbury itself isn't.

**The curve is the straight side of the triangle, and the other two routes are more curved than the curve - glad we cleared that up.

[ellendune]

Happy to have third rail up from Southampton area to Wiltshire and taking it to Bristol; I doubt the good folks of Bath would complain about it being unsightly.

Apart from the safety considerations, the additional cost of DC^▸ (Direct Current) power equipment (more substation and the need for rectifiers). Does the amount of traffic justfy electrification on this line? Surely there are higher priorities. It cannot even be justified as infill! Even west of Bathampton there would only be the Southampton Bristol services using it as the IET^▸ (Intercity Express Train)'s don't run on DC. Electrifying Bathampton to Bristol on 3rd Rail would be extremely short-sighted and a waste of money! 

New electrification should be 25kV OLE^▸ (Overhead Line Equipment, more often "OHLE").

[broadgage]

Agree, all new electrification should be 25KV AC .
Third rail should be confined to existing routes and to very minor additions, infills, and extensions in third rail areas.

The former "Southern" third rail system is allegedly the largest in the world, and is much more extensive than is sensible at such a low voltage. It was never properly planned, but "just sort of grew".

The merits of DC^▸ (Direct Current) electric trains over steam power became clear about 100 years ago for intensively used inner suburban routes, and then gradually spread to the outer suburbs and eventually as far as the south coast.

Third rail needs relatively low voltages, and that needs frequent substations which adds to expense for equipment and land purchase.
A lethal voltage exposed at ankle height is a greater danger than a much higher voltage that is well out of reach.

[Noggin]

AIUI^▸ (as I understand it), the view of the various regulatory bodies on 3rd rail is that you can only extend it for short stretches where you can very tightly control access to the tracks and there's no other option.

In other words, something like new sidings/depots is permissible, the underground extension to Battersea is fine and you could probably get away with well-fenced urban cutting/viaduct. But don't even think about new third rail through open country, with level crossings etc.     

 

[broadgage]

AIUI^▸ (as I understand it), the view of the various regulatory bodies on 3rd rail is that you can only extend it for short stretches where you can very tightly control access to the tracks and there's no other option.
In other words, something like new sidings/depots is permissible, the underground extension to Battersea is fine and you could probably get away with well-fenced urban cutting/viaduct. But don't even think about new third rail through open country, with level crossings etc.     

Yes, for safety reasons, significant expansion is effectively prohibited, and for financial reasons no one in the rail industry WANTS any significant expansion.

[Adelante_CCT]

From different thread:

Testing the overhead for the first time between Newbury and Reading/Scours Lane

More IET^▸ (Intercity Express Train) overhead testing pencilled in for this coming Tuesday & Wednesday, with class 387 testing for the first time Wednesday & Thursday night

[Dispatch Box]

Happy to have third rail up from Southampton area to Wiltshire and taking it to Bristol; I doubt the good folks of Bath would complain about it being unsightly.

Apart from the safety considerations, the additional cost of DC^▸ (Direct Current) power equipment (more substation and the need for rectifiers). Does the amount of traffic justfy electrification on this line? Surely there are higher priorities. It cannot even be justified as infill! Even west of Bathampton there would only be the Southampton Bristol services using it as the IET^▸ (Intercity Express Train)'s don't run on DC. Electrifying Bathampton to Bristol on 3rd Rail would be extremely short-sighted and a waste of money! 

New electrification should be 25kV OLE^▸ (Overhead Line Equipment, more often "OHLE").

Yes, Probably dead in the water, Better to get Bath Electrified, which should be next year,The Government will have more money by not giving it to the EU^» (European Union - about).  I Am lead to believe from information I have, is that Bath has part been started on and just needs finishing off by completing the Resignalling Then putting up the wires.