Great Western Main Line electrification - ongoing discussion

[whole diary]

[stuving]

Aluminium has a higher resistance than copper. Hopefully nothing more than the fact that the electricity meter will turn more for each train.

Not an issue. The rail sections are joined so it acts as a conductor too, and its cross-sectional area is much greater than the conductor wire itself (2100 vs 100-161 mm²). So the OLE^▸ (Overhead Line Equipment, more often "OHLE") through the tunnel has a very low resistance - which should mean that no feed is needed inside the tunnel, too.

[broadgage]

Indeed, the wire used in this rigid overhead supply system is not comparable to the overhead wire in a catenary system.
It is more akin to a "wearing strip" with the majority of the current being conducted for most of the distance by the conductor bar system to which the wire is fixed.

Despite this, aluminium is not ideal for a sliding contact system. Aluminium forms an oxide layer on exposure to the air, this oxide is electrically insulating. 25 Kv readily breaks down this oxide, but the contact is still inferior to that provided by copper, with more sparking and more heat produced.
The thin film of oxide that is removed by each pass of a pantograph is also very abrasive and I would expect more rapid wear of the contact strip on the pantograph to result.

Experts have obviously considered these drawbacks to be a price worth paying in view of the problems experienced with copper contact wire in the tunnel.

[Bmblbzzz]

A general question about electrification of locomotives/rolling stock across the UK^▸ (United Kingdom): I've just read that "only 42% of track in the UK is electrified and 29% of Britain’s current fleet is run solely on diesel fuel." Here. This implies that 71% of Britain's rail fleet is either pure electric or hybrid (and I'd imagine a tiny percentage being batteries or experimental technologies like hydrogen). That seems a surprisingly high percentage to me given that only 42% of track is electrified, even allowing for that presumably being the busiest track.

[paul7575]

A general question about electrification of locomotives/rolling stock across the UK^▸ (United Kingdom): I've just read that "only 42% of track in the UK is electrified and 29% of Britain’s current fleet is run solely on diesel fuel." Here. This implies that 71% of Britain's rail fleet is either pure electric or hybrid (and I'd imagine a tiny percentage being batteries or experimental technologies like hydrogen). That seems a surprisingly high percentage to me given that only 42% of track is electrified, even allowing for that presumably being the busiest track.

If the fleet is broken down by individual vehicle or coach numbers I expect the average DMU^▸ (Diesel Multiple Unit) is about just over 2 cars long, and the average EMU^▸ (Electric Multiple Unit) is somewhat over 4 cars long.  That alone probably skews the numbers.

Paul

[grahame]

If the fleet is broken down by individual vehicle or coach numbers I expect the average DMU^▸ (Diesel Multiple Unit) is about just over 2 cars long, and the average EMU^▸ (Electric Multiple Unit) is somewhat over 4 cars long.  That alone probably skews the numbers.

Indeed.  Further, there are some thin strings of track with sparse/poor service ... Inverness to Wick and Thurso, Dingwall to Kyle of Lochalsh, Craigendoran to Mallaig, Crainlarich to Oban, Chippenham to Trowbridge, Ayr to Stranraer, Dovey Junction to Pwhelli, Llanelli to Craven Arms.   And still a number of secondary and freight lines - none especially long these days, but that all add up, accounting for track mileage but (I wonder) perhaps not "fleet" if you count passenger vehicles.

[Bmblbzzz]

Thanks. I hadn't thought about counting each car individually.

[onthecushions]

Looks like there were four electrically hauled return workings through the 7 tunnel last night, 3Z33/40, running between Patchway and Long Dyke - presumably pan down at Newport.

Any further news?

OTC

[Western Pathfinder]

Also testing of the bidirectional running on the up through Pilning.

[grahame]

Also testing of the bidirectional running on the up through Pilning.

I get my ups and downs mixed up.  That's testing that trains can run from the Bristol direction on the line that has the operational platform, right?

[Western Pathfinder]

Also testing of the bidirectional running on the up through Pilning.

I get my ups and downs mixed up.  That's testing that trains can run from the Bristol direction on the line that has the operational platform, right?

Spot on Grahame.

[SandTEngineer]

Reported elsewhere that the Severn Tunnel won't be ready for general electric use on 12 December 2019 as planned.  Likely to be late January 2020.  So diesel west of Pilning for now.......

[onthecushions]

A snippet from another Board this morning (6/12):

".. the prime minister promised in an interview with BBC^» (British Broadcasting Corporation - home page) East Midlands Today that, if re-elected, the MML^» (Midland Main Line. - about) electrification would be completed to Nottingham/Sheffield."

If this is so then the rest of our GW^▸ (Great Western) wiring is certain.

Pity we don't have an election every week.

OTC

[onthecushions]

Found the quote (Derbyshire Live):

"Electrification of the Midland Main Line could be back on again, according to Prime Minister Boris Johnson.

He was speaking during a visit to luxury knitwear company John Smedley, in Lea Bridge, near Matlock, on Thursday afternoon and was reacting to an accusation that the East Midlands was being neglected in future plans for improved infrastructure.

The £1.1 billion plan for electrification of 70 miles of railway between Kettering and Chesterfield was scrapped by Theresa May's government in 2017.

It would have seen the line electrified through to Sheffield.

Even though bi-mode trains, which switch from diesel to electric mid-journey, are reported to be on order, Mr Johnson said on Thursday: "We should bring electrification of Midland Mainline back and do the whole line through to Sheffield.

"It is also the right thing for the environment for passengers and commuters. We are also committed to reversing some of the cuts that Beeching instigated in the 1960s and will reinstate some lines that were lost then."
Crowds gathered to hear Boris Johnson speak (Image: Derby Telegraph)

Mr Johnson said that several electrification projects across the country had been cut by then Chancellor of the Exchequer George Osborne and added: "I am going to bring it back and get it done. I believe there are ways in which funding for long-term projects can be found which don't lift borrowing costs."

Well done. whoever challenged him.

OTC

[IndustryInsider]

Promises, promises... 

[SandTEngineer]

Reported elsewhere that the Severn Tunnel won't be ready for general electric use on 12 December 2019 as planned.  Likely to be late January 2020.  So diesel west of Pilning for now.......

Updated news from the WNXX^▸ (Stored Unserviceable, Mainline Locos HQ All Classes) Forum.  Effective 15/12/2019:

The (GWR^▸ (Great Western Railway)) brief that has gone out advises that it is pan up at Newport and pan down at Severn Tunnel before putting it up again at Pilning.