Which section of track would most benefit from a 140mph line speed?

[philosopher]

Excluding HS1, there are currently no sections of track in the UK with a line speed greater than 125mph. Therefore, if issues of cost were ignored, which stretch of track would most benefit from having its line speed raised to 140mph. By section of track I mean a stretch of track of between 20 and 100 mph.

I assume such a section would be towards the longer end in terms of distance to allow for the greatest saving in journey time, would be used by mostly 140 mph capable rolling stock and have few or no slower services sharing the track.

 

[zwk500]

For some comparison,
1 mile @ 100mph = 36 secs
1 mile @ 125mph = 29 secs
1 mile @ 140mph = 26 secs

So to save 1 minute with 140mph vs 100mph track you need 6 miles of uninterrupted upgrade. To save 1 minute with 140mph vs 125mph track you need 20 miles of uninterrupted upgrade. I'm struggling to think of anywhere where an existing upgrade would be better value than either a new route at 155-180mph or 75mph slow lines to get freight off the 125mph lines.

 

[Zomboid]

Bristol to Exeter is mostly 100mph - I'm not sure 140 is necessary (or possible without electrification), but it's a long stretch that might benefit from going to 125. Likewise Reading to Taunton.

 

[quantinghome]

Based on the criteria I suspect Stirling-Aberdeen would be in with a good shout.

 

[The Planner]

What is the end goal here? if you have station stops then the benefits are reduced immediately, if anything is running slower than 140 then the benefits are reduced immediately. As @zwk500 notes, you need some long distances to make a small dent in journey time. You wouldn't even manage 2 minutes saving between Reading and Swindon for example.

 

[Zomboid]

Assuming the geometry is actually possible which it probably isn't, would you get more or less benefit to the London to Bristol Parkway journey time by making the diverging route at Wooton Basset 100 (currently 70) or Reading - Swindon 140?

 

[The Planner]

Assuming the geometry is actually possible which it probably isn't, would you get more or less benefit to the London to Bristol Parkway journey time by making the diverging route at Wooton Basset 100 (currently 70) or Reading - Swindon 140?

The latter, you only need a ½ minute adjustment to/from the Badmintons.

 

[stuu]

Bristol to Exeter is mostly 100mph - I'm not sure 140 is necessary (or possible without electrification), but it's a long stretch that might benefit from going to 125. Likewise Reading to Taunton.

NR were looking at 125 between Bristol and Taunton at one point, the horizontal alignment is as good as HS2 but there's lots of other factors that need to be considered. You wouldn't get much more speed out of Reading-Taunton-Exeter without getting the diggers out though

 

[Brubulus]

Easiest upgrade would be Stoke Jn to Tallington, however it would save half a minute at most. Then as ETCS rollout widens, 140 can be rolled out more widely.

However, I understand that Germany has upgraded existing lines to 250kmh, would this be possible in the UK
(it may require upgrades/regearing to 80x though that is likely possible, however it might require more separation between tracks, which would be a big problem)

250kmh/155mph is a substantial speed increase over 125mph and if the difference in necessary investment is relatively small, is probably worth it, however the speed differential becomes more of an issue.

NR were looking at 125 between Bristol and Taunton at one point, the horizontal alignment is as good as HS2 but there's lots of other factors that need to be considered. You wouldn't get much more speed out of Reading-Taunton-Exeter without getting the diggers out though

Bristol-Taunton, alongside Bromsgrove-Bristol Parkway should be 125, it would substantially speed up XC however I understand there are too many AHB level crossings on the line from Bromsgrove to Bristol.

 

[zwk500]

Easiest upgrade would be Stoke Jn to Tallington, however it would save half a minute at most. Then as ETCS rollout widens, 140 can be rolled out more widely.

In-Cab signalling is a tiny part of 140mph running. Swingnose crossings, closed off platforms, tighter OLE standards, greater dynamic profile clearances...

 

[I'm here now]

Is there a report on that?

 

[MatthewHutton]

In-Cab signalling is a tiny part of 140mph running. Swingnose crossings, closed off platforms, tighter OLE standards, greater dynamic profile clearances...

Platform edge doors at e.g Didcot would probably be one of the stronger places to do it as you could also reduce dwell times on the express services that stop.

The other platforms probably could be closed except possibly Slough (but you could also do PEDs there)

 

[yoyothehobo]

I do look forward to the Far North Line Shinkansen being opened between Inverness and Thurso rapidly improving journey times.

 

[SynthD]

Platform edge doors at e.g Didcot would probably be one of the stronger places to do it as you could also reduce dwell times on the express services that stop.

The other platforms probably could be closed except possibly Slough (but you could also do PEDs there)

Slough has gated off main platforms. From Ealing to Didcot all the main line platforms could be behind manned gates to permit higher speed running. Reading is the only exception, which is OK because everything stops there. After that, to Royal Wotton Basset (and perhaps beyond, outside the town) is harder to deal with as it's just two lines.

Is the benefit intended for the fastest trains on that line (regardless of other services), or for all trains (where a greater difference from slowest to fastest train reduces capacity)?

 

[philosopher]

Assuming the geometry is actually possible which it probably isn't, would you get more or less benefit to the London to Bristol Parkway journey time by making the diverging route at Wooton Basset 100 (currently 70) or Reading - Swindon 140?

Reading to Swindon I think is about 40 miles, so my guess is that an upgrade from 125 to 140 mph would save a minute after acceleration is taken into account. However west of Didcot almost all the passenger trains are 140 mph capable and between Reading and Didcot the slower trains are on the relief lines. There are I think 5 passenger trains per direction on this section of track, so if a minute saving per train is correct, in total you would save 10 minutes per hour for all services, which is a reasonable saving. I am not sure how many freight services there are on this section of line though which could reduce the benefits of such an upgrade.

 

[zwk500]

I am not sure how many freight services there are on this section of line though which could reduce the benefits of such an upgrade.

https://www.realtimetrains.co.uk/se...6-05/0000-2359?stp=WVS&show=freight&order=wtt A fair bit, although lots of paths that don't always run.

 

[YorkshireBear]

I do look forward to the Far North Line Shinkansen being opened between Inverness and Thurso rapidly improving journey times.

Be a lot of level crossings to close!

 

[Harpo]

Pointless having 140mph on the Western while virtually every train is all-shacks and trains crawl into station stops.

WCML will surely have more frequent stops when HS2 opens?

ECML it is.

 

[The Planner]

Reading to Swindon I think is about 40 miles, so my guess is that an upgrade from 125 to 140 mph would save a minute after acceleration is taken into account. However west of Didcot almost all the passenger trains are 140 mph capable and between Reading and Didcot the slower trains are on the relief lines. There are I think 5 passenger trains per direction on this section of track, so if a minute saving per train is correct, in total you would save 10 minutes per hour for all services, which is a reasonable saving. I am not sure how many freight services there are on this section of line though which could reduce the benefits of such an upgrade.

But its still only a feasible minute per train that you might not be able to make use of.

 

[MatthewHutton]

Reading to Swindon I think is about 40 miles, so my guess is that an upgrade from 125 to 140 mph would save a minute after acceleration is taken into account. However west of Didcot almost all the passenger trains are 140 mph capable and between Reading and Didcot the slower trains are on the relief lines. There are I think 5 passenger trains per direction on this section of track, so if a minute saving per train is correct, in total you would save 10 minutes per hour for all services, which is a reasonable saving. I am not sure how many freight services there are on this section of line though which could reduce the benefits of such an upgrade.

Surely if Didcot-Swindon is only a ~30 second speed up the freight isn’t that relevant?

 

[Egg Centric]

For some comparison,
1 mile @ 100mph = 36 secs
1 mile @ 125mph = 29 secs
1 mile @ 140mph = 26 secs

So to save 1 minute with 140mph vs 100mph track you need 6 miles of uninterrupted upgrade. To save 1 minute with 140mph vs 125mph track you need 20 miles of uninterrupted upgrade. I'm struggling to think of anywhere where an existing upgrade would be better value than either a new route at 155-180mph or 75mph slow lines to get freight off the 125mph lines.

This is absolutely correct. The logical way therefore to answer the question as posed in the OP is not to be looking at 125mph track, or even 100mph track. It's to search out <=60mph track (since we have a magic upgrade with no cost wand here) and convert it to 140mph with our wand.

There's then broadly two possible approaches I think:

1. We resurrect my highly underappreciated idea of a rollercoaster train and "remodel" one of the London termini (perhaps Waterloo or Victoria?) throats. By which I mean keep the existing layout but just run everything through it at 140mph (maybe using super strong magnets to prevent derailments or something, I don't know) and strap the passengers down to prevent them from being seriously injured.
2. If we want a more conventional layout, we pick some of the East Anglian lines, probably everything starting in Norwich tbh - and where currently they are limited due to sinking into the fens we magically fix that. We may need to close a certain station to really make the most of this but imo Thomas Berney would understand.

 

[cle]

I would think Stevenage/Hitchin (let the Cruisers leave) to Peterborough would benefit the most trains.

Or Rugby - Rugeley fast lines?

Or upgrade north of Carlisle ?

MML is too windy and frankly not busy enough for the investment / potential.

GWML has the right profile but stops are too frequent, and most markets important enough. Other than B&H which might not work, and doesn’t carry enough trains.

 

[Bald Rick]

ignoring the ‘if costs are ignored’ criteria, the easiest section in the country to do is Temple Hirst to Colton Jn. Not least because it was built for higher speed. When ETCS is done, “all” that will need doing is 7 sets of swing nose points, an OLE upgrade, and a lot of paperwork. Saves about half a minute.

Next would be Newbold Jn (just north of Rugby) to Colwich, but excluding the Nuneaton area; same reasons, same work except 21 set of swingnoses to go in. Saves 90 seconds.

 

[zwk500]

ignoring the ‘if costs are ignored’ criteria, the easiest section in the country to do is Temple Hirst to Colton Jn. Not least because it was built for higher speed. When ETCS is done, “all” that will need doing is 7 sets of swing nose points, an OLE upgrade, and a lot of paperwork. Saves about half a minute.

Next would be Newbold Jn (just north of Rugby) to Colwich, but excluding the Nuneaton area; same reasons, same work except 21 set of swingnoses to go in. Saves 90 seconds.

What about Skelton Bridge Junction to Northallerton south Jn Fasts lines? It's pretty straight, and Thirsk has already had the platforms removed, so you'd need the swingnose crossings at Tollerton (6*) and Thirsk (5*), the OLE and Paperwork. About 24 miles, could save about c.60 seconds.

Not sure how useful that minute is given constraints at York and Darlington, and once Darlignton's finished Durham/Chester-le-Street...

* - If swingnoses not required on slow line end of crossovers and no layout changes.

 

[The exile]

Sure as much time could be saved by reverting to the approach speeds into (through) stations that were once the norm (and still are elsewhere). The crawl into the odd numbered platforms at Bristol TM when there is nothing occupying the other end of the platform is excruciating.

 

[milooo]

I would think Stevenage/Hitchin (let the Cruisers leave) to Peterborough would benefit the most trains.

Or Rugby - Rugeley fast lines?

Or upgrade north of Carlisle ?

MML is too windy and frankly not busy enough for the investment / potential.

GWML has the right profile but stops are too frequent, and most markets important enough. Other than B&H which might not work, and doesn’t carry enough trains.

Maybe a bit after Hitchin so there is time for the cambridge services to clear the line

 

[Bald Rick]

What about Skelton Bridge Junction to Northallerton south Jn Fasts lines? It's pretty straight, and Thirsk has already had the platforms removed, so you'd need the swingnose crossings at Tollerton (6*) and Thirsk (5*), the OLE and Paperwork. About 24 miles, could save about c.60 seconds.

Headspans. Would be much more OLE work than the other two, I expect.

 

[Zomboid]

Would doing as much of the ECML as seems credible with current alignments save enough time to offset a meaningfully capacity increasing reduction in line speed through Welwyn without adversely impacting journey times?

 

[MarkyT]

Would doing as much of the ECML as seems credible with current alignments save enough time to offset a meaningfully capacity increasing reduction in line speed through Welwyn without adversely impacting journey times?

125mph doesn't begin until north of Woolmer Green already, with the down fast speed 115mph south thereof, rising from 100mph around Potters Bar. On the up, there's a 105mph restriction through the tunnels on the 2-track section, after which it's also 115mph to Potters Bar. Going slower still would only require slowing and acceleration for the majority of trains. ETCS is planned to have additional shorter blocks through the bottleneck, which should marginally improve capacity and reliability by allowing trains to follow each other more closely.

 

[brad465]

ignoring the ‘if costs are ignored’ criteria, the easiest section in the country to do is Temple Hirst to Colton Jn. Not least because it was built for higher speed. When ETCS is done, “all” that will need doing is 7 sets of swing nose points, an OLE upgrade, and a lot of paperwork. Saves about half a minute.

Next would be Newbold Jn (just north of Rugby) to Colwich, but excluding the Nuneaton area; same reasons, same work except 21 set of swingnoses to go in. Saves 90 seconds.

IIRC the Selby divert is good for 155mph, however the problem there of course is neither the Azumas or anything else on the route are able to achieve this in passenger service.

125mph doesn't begin until north of Woolmer Green already, with the down fast speed 115mph south thereof, rising from 100mph around Potters Bar. On the up, there's a 105mph restriction through the tunnels on the 2-track section, after which it's also 115mph to Potters Bar. Going slower still would only require slowing and acceleration for the majority of trains. ETCS is planned to have additional shorter blocks through the bottleneck, which should marginally improve capacity and reliability by allowing trains to follow each other more closely.

There's also a section of 100-105mph between Peterborough and Huntingdon, which IIRC is down to ground stability reasons. If any line speed improvements are to be made on the ECML south of Peterborough, this is where I'd start.

Regarding the wider question, the sections I'd go for 140mph upgrades are the ones where the headline journey time of a route goes below a particular hour threshold, as the PR/advertising potential for the route is much better given human psychology. So if there's a route that takes say 3h4m currently, if enough sections of upgradable track reduce this by 5 minutes, one could sell a sub-3h journey time. In contrast, a route with a journey time of 3h25m that could be reduced by 10 minutes would not sell as well, even though the raw saving is higher.