Great Western Main Line electrification - ongoing discussion

[whole diary]

[DidcotPunter]

Worth noting though that it is only the main lines that are complete. There are still sections of the contact wire missing on the relief lines, for example, at Goring and Cholsey.

Yes, and also between Moreton Cutting and through Didcot station to Milton Junction where none of the relief lines are wired (yet).

[Electric train]

I returned from Oxford to Reading on the 2252 stopper last night (18/7) and counted 22 separate working electrification vehicles (platforms with telescopic arms etc) on the main lines with 6 trackside work areas.

Very impressive.

OTC

Them things are called MEWP^▸ (Mobile Elevating Working Platform)

For those vaugly interested class 800 running on GW^▸ (Great Western) juice https://www.youtube.com/watch?v=UrNF2euHs_0&feature=player_embedded

[chrisr_75]

I returned from Oxford to Reading on the 2252 stopper last night (18/7) and counted 22 separate working electrification vehicles (platforms with telescopic arms etc) on the main lines with 6 trackside work areas.

Very impressive.

OTC

Them things are called MEWP^▸ (Mobile Elevating Working Platform)

For those vaugly interested class 800 running on GW^▸ (Great Western) juice https://www.youtube.com/watch?v=UrNF2euHs_0&feature=player_embedded

Just to elaborate on that acronym for anyone unfamiliar - Mobile Elevating Work Platform

[Chris from Nailsea]

Indeed - it's also already in our acronyms / abbreviations page, above, at http://www.firstgreatwestern.info/acronyms.html 

[onthecushions]

Them things are called MEWP^▸ (Mobile Elevating Working Platform)

Yes but are they driving, trailer, brake, first, standard, composite, corridor, open, lavatory or if used on LUL^▸ (London Underground Ltd) uncoupling? (etc)

OTC

[ChrisB]

They were specified as being able to change over on the move.....

[TonyK]

"On the fly" to use the jargon. Pants up or down.

[NickB]

Apologies for the digression, and also if this has been asked before.
As I was standing at Maidenhead station this morning admiring the new gantries I was struck with the question of what happens as the track crosses the Thames at brunel's lovely bridge?
Will the cabling span the bridge, in which case should I admire the view now before it is spoilt forever by suspended cabling, or does something else happen to break the overhead continuity before it picks up again on the other side (perhaps slip it in neutral and coast over?) 😀

[paul7575]

Sorry to disappoint, but yes, the normal cables will definitely go over the bridge.  The support structures may well be tailored to the location, (I don't think we've seen the details yet) and will be positioned to suit the piers of the bridge, rather than the normal distances apart. 
Something different to the usual has already been fitted at Moulsford, a more lightweight centrally mounted cantilever system.  So I suggest that Maidenhead bridge may be similar.

There are any number of listed bridges around the country with OHLE added, on both the ECML^▸ (East Coast Main Line) and WCML^▸ (West Coast Main Line) for a start.

Paul

[SandTEngineer]

There is a bit of info here on how Maidenhead bridge will be but no pictures (yet): http://openbuildings.com/buildings/maidenhead-railway-bridge-profile-10598?_show_description=1

...but later I did find this : https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.rbwm.gov.uk/pam/docservlet%3FdocId%3D139756288%26filename%3D1985224.pdf%26mimeType%3Dapplication/pdf&ved=0ahUKEwiH98-X8JbOAhXLDMAKHZkZCugQFghTMBA&usg=AFQjCNF99o9MRtp_cvz53jXMfO5klEWpow&sig2=RdWenYh-q3KdhB9h5MhvjQ

[paul7575]

Can they not reduce the amount of knitting, a rackets and insulators etc by running the ATF and screen conductor along the ground using insulated cable within troughing like they apparently do in tunnels?

Paul

[chrisr_75]

I think we need to keep this in perspective a bit here - the bridge is listed due to its significance from an engineering point of view, not for it's visual appearance, architectural or cultural importance, so I think adding the electrification stuff really is not an issue.

[Oxonhutch]

The things that run over it are not original Brunel either - despite what some would have us believe.

[stuving]

Can they not reduce the amount of knitting, a rackets and insulators etc by running the ATF and screen conductor along the ground using insulated cable within troughing like they apparently do in tunnels?

Paul

The screen conductor is always with the other (non-OLE^▸ (Overhead Line Equipment, more often "OHLE")) cables. That "Heritage Deed Method Statement" makes the point that the revised ATF design has fewer overhead cables than the previous "booster" transformer one (10 vs 15). And putting the ATF right over the pillar on a small mast does use the least metal to hold it up. Also, I'm sure there are some special rules about working on cables near ground-level 25 kV conductors.

The performance of the AT system does ultimately depend on the impedance balance between the two current paths (conductor/catenary and ATF), so perhaps that limits the amount of those you can use.

[chrisr_75]

The things that run over it are not original Brunel either - despite what some would have us believe.

Indeed! I think Brunel would be really rather impressed to see how his creation has evolved/is evolving into a modern electric railway with 125mph trains and also with the equipment that assists with its construction. He should/would also be rightly proud of his groundbreaking (literally!) civil engineering that gave us the flat, straight GWML^▸ (Great Western Main Line) as a basis to work with - far fewer barriers in the way of running fast trains and an efficient timetable on the GWML than that stood in the way of the various WCML^▸ (West Coast Main Line) modernisations.