Infrastructure alteration for electrification

[whole diary]

[FarWestJohn]

Yesterday as a blue sky and I had the day off I walked the old line from Yelverton into Plymouth and then on to Laira bridge. When passing under the new[ish] Marsh Mills concrete A38 flyover I could not help but notice the headroom of the track on the main line. A Voyager went under and it did not look as though there is enough clearance for an overhead catenary. The problem looked worse on the up line under the up slip road. Surely a modern structure such as this must have been constructed allowing for the required headroom?

This led me on to thinking what other structures would need altering before OHLE could be installed? If mainly a lot of small road overbridges then they could be done fairly quickly in advance.

As the Government is looking for quick public works with a lot of labour content then this could be ideal as it would give work to the construction industry that is suffering a downturn. Come the day of OHLE installation the works trains could work more efficiently as the preparatory work would have been completed.

Perhaps I am being too simplistic but I would be interested to know what quantity of structures would be involved. I am sure one of the members must have an idea?

(1555 train back to Cornwall was a 150 and horrendously crowded, not good as this train hits the jackpot of all stations from Plymouth to Penzance. It also sounded as if the driver was having trouble as it spent a lot of its time crawling along coasting with the occasional burst of power.)

Web site still very good.

[IndustryInsider]

The extra clearance needed is not as large as some people think, and in some situations the required height can be achieved by lowering the track slightly. Our resident expert, 'ElectricTrain', might be able to elaborate further?

[smithy]

agree lowering track is an option,i believe this is going to be happening in the tunnel coming out of southampton to accomodate the continental freight wagons in the not too distant future.

[Zoe]

I don't think electrification is likely to reach Plymouth though due to the Dawlish sea wall and the loading gauge in the Dawlish tunnels.

[6 OF 2 redundant adjunct of unimatrix 01]

what are the downsides to '3rd rail'

[miniman]

what are the downsides to '3rd rail'

I suspect as it is a lower voltage it requires more lineside equipment to keep the voltage up (greater losses over a shorter distance) so it is better suited to areas where there are a lot of stations already there. Also I would guess that it simply doesn't deliver as much "grunt" as overhead.

[smokey]

what are the downsides to '3rd rail'

Mayor problem with 3rd rail is Elf & safety, whilst Fill in schemes are allowed, NEW 3rd rail schemes are Not premitted on Elf & Safety grounds.

[Btline]

Max speed of 100 mph (the world record held by a Wessex Electric is only about 115 I think!).

I could give a rant about my views on Health and Safety, but I'll spare everyone.

Just two words- common sense.

[6 OF 2 redundant adjunct of unimatrix 01]

thankyou guys i suspected it was safty reasons i always did think it was silly and tbh dangerous

[Chris from Nailsea]

Web site still very good.

Well, thank you, FarWestJohn! 

[Electric train]

The extra clearance needed is not as large as some people think, and in some situations the required height can be achieved by lowering the track slightly. Our resident expert, 'ElectricTrain', might be able to elaborate further?

A dynamic (ie after contact wire is lifted by the passage of the pan) clearance of around 600mm between any live components and anything at earth potential, in some very special cases the clearance is less by using insulating covering on the under side of bridges.

It has been policy since the early 1980's that any new structures needed to take into account any future 25kV electrification some exceptions are the SR^‡(resolve) and a few other areas, my guess is the route to Plymouth would need to take 25kV into account.  The use of dual voltage was abandoned in the 1970's the lines such as Liverpool St to Shenfield, Fenchurch to Southend and around Glasgow used 6.25kV where there were low bridges, this added complications such as out of sequence controls in substations to allow for emergency moving failed trains and extra line side equipment to step the voltage down dual voltage stock etc

[IndustryInsider]

The extra clearance needed is not as large as some people think, and in some situations the required height can be achieved by lowering the track slightly. Our resident expert, 'ElectricTrain', might be able to elaborate further?

A dynamic (ie after contact wire is lifted by the passage of the pan) clearance of around 600mm between any live components and anything at earth potential, in some very special cases the clearance is less by using insulating covering on the under side of bridges.

It has been policy since the early 1980's that any new structures needed to take into account any future 25kV electrification some exceptions are the SR^‡(resolve) and a few other areas, my guess is the route to Plymouth would need to take 25kV into account.  The use of dual voltage was abandoned in the 1970's the lines such as Liverpool St to Shenfield, Fenchurch to Southend and around Glasgow used 6.25kV where there were low bridges, this added complications such as out of sequence controls in substations to allow for emergency moving failed trains and extra line side equipment to step the voltage down dual voltage stock etc

Top-notch bit of elaboration there! 

[eightf48544]

Another problem initialy with the 6.25/25kv mix was the strain it put on the board equipment on the units such that it caused the transformers to blow up. This was especialy so in Glasgow where it was first used. I believe unfortunately there might have been fatalities on a train when its transformer blew. It was so bad that all EMUs^▸ (Electric Multiple Unit) were withdrawn and some steam locos and stock were hastily put back into service. Although the units did come back into use with strengthened transformers and proved very successful, such that Glasgow now has an almost all electric suburban service with new lines and stations.

There were also several instances out of Liverpool Street particularly on the services via Hackney Downs.
   

[woody]

agree lowering track is an option,i believe this is going to be happening in the tunnel coming out of southampton to accomodate the continental freight wagons in the not too distant future.

Regards the forthcoming blockade of one of the twin bore Marley tunnel between Totnes and Plymouth(Engineering work between Newton Abbot and Plymouth from Monday 26 until Friday 30 January 2009) does anyone know if lowering of the track for possible future electrification is being undertaken as part of the work.

[signalandtelegraph]

agree lowering track is an option,i believe this is going to be happening in the tunnel coming out of southampton to accomodate the continental freight wagons in the not too distant future.

Regards the forthcoming blockade of one of the twin bore Marley tunnel between Totnes and Plymouth(Engineering work between Newton Abbot and Plymouth from Monday 26 until Friday 30 January 2009) does anyone know if lowering of the track for possible future electrification is being undertaken as part of the work.

No, NR^» (Network Rail - home page) are not that far sighted enough.