Great Western Main Line electrification - ongoing discussion

[whole diary]

[Bmblbzzz]

That's my vague suspicion...

[TonyK]

Does "deployment of newer technology" mean hydrogen fuel cells? Or perhaps CNG^▸ (Compressed Natural Gas)?

CNG would  be locking the railways into internal combustion engines and fossil fuels. Although it is often perceived to be cleaner than diesel, it is usually used in spark ignition engines that are less energy efficient than diesel, so aren't any better in terms of carbon. Indeed they can be worse.  Biomethane can be used, but there is only so much organic waste to digest and we need to do something about domestic heating and other natural gas uses as well.

Diesel beats CNG in terms of energy density, biomethane is already getting to the point of growing crops and transporting them substantial distances to the digester rather than using waste - and there have been pollution incidents - and hydrogen has to be made either by electrolysis or knocking the carbon atoms off methane, but the means of production of different fuels is a different debate / argument. We have had only three main sources of motive power in the entire history of railways - steam, diesel and electricity. I know about the gas turbine engine and the People Mover, but it has been only those three, of which two remain in daily use on the national network, and one of them is only because we haven't gotten around to catching up with the continentals. There may be exciting new developments around the corner, or the minister may be trying to put off saying that electricity is the only practical way forward. If it is the latter, then we will be having the same conversation in 25 years' time as we had 45 years ago, as we try to extend the life of ageing hybrid stock while we have another in-depth survey, to report after the imminent election, into what we do next.

Let's challenge the experts to come forward with their ideas for moving trains from A to B on the national rail network using whatever means they think possible, with an appendix to the report giving a peer-reviewed analysis of the advantages of the proposed system over 25,000 KV AC OHLE as the method of delivery of the energy required. But let us not pause electrification again while we wait for it.

[Bmblbzzz]

My fear is that "development of newer technology" means either "we don't know" or "we're going to call these diesel engines newer technology because they meet the latest standard". Both sound like a way of avoiding commitment to electrification.

[Electric train]

This popped up on the WNXX^▸ (Stored Unserviceable, Mainline Locos HQ All Classes) Forum:

Seems electrification is genuinely back on the agenda at the DfT^» (Department for Transport - about) - see Grant Shapps written reply to the Transport Committee, sent on Feb 17th and published a few days ago:

You told us (Q37) that we could expect to see greater use of electrification on the railways. Can you provide some more detail on your plans to make greater use of electrification?

"The Rail Industry Decarbonisation Taskforce has been clear that greater use of electrification, alongside deployment of newer technology, will be needed. Electrification will play a significant role in our programme to achieve our Net Zero 2050 objective. Network Rail’s ongoing work will inform decisions about whether electrification or new technologies are the better option for each individual section of the network where diesel trains currently run and considers both passenger and freight services. This is a complicated process and it is right to take the time to do this properly.

I will consider the case for exploring some electrification schemes more quickly as development of the strategy progresses. In deciding which early schemes to take forward, we will be considering the environmental impact as well as factors such as affordability; readiness of a scheme to proceed; deliverability; the disruption that might be experienced by passengers or freight operators during works; and availability of suitable rolling stock.

We have noted the helpful work undertaken by the Railway Industry Association about the cost of electrification and will ensure that lessons are learnt from previous electrification schemes and those currently underway, including in Scotland and Wales. We will continue to ensure that new schemes deliver value for money for taxpayers and that the industry is able to deliver a decarbonisation programme in a sustainable way"

https://committees.parliament.uk/download/file/?url=%2Fpublications%2F116%2Fdocuments%2F845&slug=letterfromgrantshappsfollowuptoevidence170220pdf

So perhaps Bristol, Oxford and Swansea back on the books again?

Yes this the case DfT have asked NR^» (Network Rail - home page) to look at a number of schemes including third rail infills that have been on the "wish list" for decades also to look at the 25kV specs.

There is a political drive to cut through the Whitehall process that have the political perception to act as a blocker and or slow the processes down too much.   The current Government want "shovels" in the ground on lots of schemes, not just rail, in time for the next General Election …………….. Yes the Government are electioneering already

[TonyK]

We will continue to ensure that new schemes deliver value for money for taxpayers and that the industry is able to deliver a decarbonisation programme in a sustainable way"

I find it comforting to see that the government is against having an unsustainable decarbonisation programme, if only to avoid the most ridiculous oxymoron to come out of Parliament. I can still hear the sound of a can being kicked down the road, though.

Let's face it, there are elephants in too many rooms. The powers that be are afraid to commit because they know that we can't afford it, especially now that we are living in very interesting times indeed. At the same time, they don't want to admit that we can't afford it, nor that the country's targets for phasing out fossil fuels are way off course, because that would be admitting defeat without the luxury of being able to blame it on the previous government.

I would hope that Bristol, Oxford and Swansea will be back on the books again, but they should have been finished either a couple of years, 30 years or 45 years ago, depending on where you want to start counting from. By now, we should have been looking at Bristol to Weston or Taunton, and between Westerleigh Junction and Bromsgrove to name but two local to me in recent times. Not looking at a yellowing wish-list of third rail infill.

[Rhydgaled]

I would hope that Bristol, Oxford and Swansea will be back on the books again, but they should have been finished either a couple of years, 30 years or 45 years ago, depending on where you want to start counting from. By now, we should have been looking at Bristol to Weston or Taunton, and between Westerleigh Junction and Bromsgrove to name but two local to me in recent times. Not looking at a yellowing wish-list of third rail infill.

As you say, it depends when you want to start counting from. In 1981 BR^▸ (British Rail(ways)) published a report detailing a number of options for extension of electrification and recomending that "if funds for railway financing were not constrained, the best course would be to choose now the largest and fastest programme." That 'largest and fastest' option would have been complete by 2001 and would have included Bristol to Penzance , Edinburgh-Aberdeen, Crewe-Holyhead etc.

Starting from where we are now, I would prioritise the Midland Main Line, Didcot-Oxford, Oxford-Bletchley (while most of it is closed for East-West Rail works) and Swindon - Bath - Bristol - Bristol Parkway. Cardiff - Swansea would follow AFTER a major capacity intervention between Cardiff and Bridgend (given the Welsh Government's target to reduce the Cardiff-Swansea travel time substatially I suggest the best way of doing this would be to build a whole new line (possibly to 125mph standards, certainly at least 90mph) between Cardiff and Bridgend).

[onthecushions]

Some positive news.

(scroll up to top of link to see picture correctly)

https://t.co/JfovcOoOTa

OTC

[grahame]

From Network Rail Media Centre

A Grade II listed bridge in Steventon, Oxfordshire, has been saved after innovative testing and the introduction of a new speed limit by Network Rail means it no longer has to be replaced as part of electrification.

The bridge over the Great Western Main Line was originally planned to be demolished and replaced with a higher bridge to allow overhead wires, needed to run trains in electric, to pass underneath enabling trains to run at 125mph.

However, following feedback from the community about how this would impact the village, Network Rail carried out state-of-the-art testing to see if the bridge could be saved.

This extensive and breakthrough testing, which included the use of computer-based simulation software, found that if the line speed of the railway was reduced to 110mph through Steventon, the wires could pass underneath the existing bridge.

This is the safest maximum speed that the overhead electric wires can be used continuously for the everyday running of the railway.

This is because the electric wires need to dip under the bridge and rise again the other side.

Mike Gallop, Network Rail’s Western route director, said:

“We are really pleased to have found a solution which means we can continue to safely run trains in electric whilst minimising impact on the community. ...

Hmmm ... what difference in journey time with 110 m.p.h. rather that 125 m.p.h. limit?

[IndustryInsider]

I reckon on about 20-30 seconds extra.  Slightly less for a westbound train that’s called at Didcot as it wouldn’t have reached 125mph by that point.

[stuving]

I reckon on about 20-30 seconds extra.  Slightly less for a westbound train that’s called at Didcot as it wouldn’t have reached 125mph by that point.

I looked at that and thought "seems about right - but I bet more than half of it is due to gentle driving and allowances". Poking about at the back of a drawer for my old model, I find it says the same - braking at full service (0.06 g) loses less than a second, and reaccelerating immediately with this set-up loses a bit over 5 seconds. Of course for a real railway (which won't fit in my drawer) there's a distance dictated for the lower speed, plus the driver has to get down there in advance, and would prefer to not apply either boot full weight.

That model set-up has a balancing speed of 160 mi/hr on the level, which might seem a bit high, but corresponds to 125 mi/hr up 1 in 106 - revised to 1 in 120, using newer weight figures plus passenger load (so not valid today). Also assumes full power available for this, for want of any better data.

[grahame]

"The Saga of Steventon Bridge" ... from the Oxford Mail ... complete with an old picture (before wires were put in) to illustrate the article, and large quantities of comments which show just how emotive the issue is locally, and just how little some people think in forming and adding their views.

[Celestial]

The difference between 110 and 125mph over a mile is 3.9 seconds.  Which would seem to suggest that when stuving's figures to decelerate and accelerate back up again are added, an overall figure of around 10 seconds is probably about right, depending how long the restricted section is.

I can understand why a driver wouldn't want to drive to the limit when decelerating, but why wouldn't they want to put the power on as much as possible to get back up to line speed, after all it was the rail industry all along that said how important it was not to have a delay here in the first instance?

One other thing interests me. As I understand it's the gradient of the contact wire between the bridge and the crossing that is the issue, would there be any difference in which direction the train is headed, as to whether the wire is falling or rising?

[TonyK]

"The Saga of Steventon Bridge" ... from the Oxford Mail ... complete with an old picture (before wires were put in) to illustrate the article, and large quantities of comments which show just how emotive the issue is locally, and just how little some people think in forming and adding their views.

You mean:

...increase wear & tear on the centenary and bow collector...

...The bridge has been there for hundreds of years...

and such like?

Some of the comments have been answered in a constructive and comprehensive way:

G* A*

25th April 1:01 pm
T* E* wrote:
Wouldn't it be possible to terminate the overhead catenary at each end of the tunnel, get the driver to lower the pantographs before entering the tunnel and allow the momentum of the train to get it through the tunnel, then the driver could then raise the pantographs to meet with the wires after passing through the tunnel.It depends how long the tunnel is of course but it could be a cheap solution if this were possible.

No.

[IndustryInsider]

The difference between 110 and 125mph over a mile is 3.9 seconds.  Which would seem to suggest that when stuving's figures to decelerate and accelerate back up again are added, an overall figure of around 10 seconds is probably about right, depending how long the restricted section is.

I can understand why a driver wouldn't want to drive to the limit when decelerating, but why wouldn't they want to put the power on as much as possible to get back up to line speed, after all it was the rail industry all along that said how important it was not to have a delay here in the first instance?

Yes, the braking would likely be done at a gentle percentage, but virtually all drivers would take full power as soon as they have passed the 110mph section - as a passenger you'd barely notice.  It does take about a minute to go from 110-125mph on level track when on full power in an IET^▸ (Intercity Express Train) - half the time a 2+8 HST^▸ (High Speed Train) takes - so I'm not sure how many seconds that would add?

[Celestial]

The difference between 110 and 125mph over a mile is 3.9 seconds.  Which would seem to suggest that when stuving's figures to decelerate and accelerate back up again are added, an overall figure of around 10 seconds is probably about right, depending how long the restricted section is.

I can understand why a driver wouldn't want to drive to the limit when decelerating, but why wouldn't they want to put the power on as much as possible to get back up to line speed, after all it was the rail industry all along that said how important it was not to have a delay here in the first instance?

Yes, the braking would likely be done at a gentle percentage, but virtually all drivers would take full power as soon as they have passed the 110mph section - as a passenger you'd barely notice.  It does take about a minute to go from 110-125mph on level track when on full power in an IET^▸ (Intercity Express Train) - half the time a 2+8 HST^▸ (High Speed Train) takes - so I'm not sure how many seconds that would add?

So remembering my various equations of motion (v=u+at and all that), I reckon if acceleration is linear then it would take 3,123m to regain 200kph if the time taken is 60 seconds, and the time lost against a steady 200kph would be 3.7 seconds (starting at 175kph).

So call it 2 secs lost to decelerate, 3.9 secs through a 1 mile speed restriction, and 3.7 secs to regain max line speed would give around 10 secs in total.