Track Singling Benefits

[The Planner]

Section 5.3 is where it all happens. Absolute block between Steel Works and Beeston so it is the running time + 2 for the headway. If the re-signalling ever happens down there, the plans had extra signals between Crewe and Beeston with both the boxes being abolished, but that was a few years ago now.

 

[geoffk]

BR was managing decline in rail travel back then and no-one could have foreseen the growth in rail use which has occurred in recent years. The same thinking applies to reduction from four to two tracks. In the area where I live, we have long single track "sidings" to Colne and Blackpool South which restrict the service interval to hourly and often result in cancellations or trains turned short of destination whenever there is disruption. In contrast, double track has remained between Settle Junction and Carnforth, which has a long block section of around 25 miles. When singling was taking place, the S&C was under threat of closure and the Little North Western was expected to accommodate these trains, continuing to Carlisle via WCML. This may be why it was never singled.

 

[Tomnick]

I thought that was what I said - it's what I meant anyway. You don't need signal boxes for Track Circuit Block and it's a shame that singling wasn't balanced by the reduction in the length of signal sections. In fact I think there are a lot of lines (even double track lines) where capacity could be increased by cutting headways for relatively little cost. Crewe to Chester? I don't know whether this level of detail is in the public domain though, the Sectional appendix shows the signalling type but not signal or section length/frequency IIRC.

Apologies if I’d misunderstood you. Even if the intermediate boxes were still in use at the time of singling, the necessary resignalling would almost certain justify abolishing them, although the cheapest way of doing it, in the past at least, precludes (as far as I understand it!) intermediate signals and flighting trains, e.g. tokenless block, “transient” TCB etc..

 

[AndrewE]

The Tran Planning Rules show the minimum headway permitted. You can find them here: http://archive.nr.co.uk/browse documents/Rules Of The Route/Viewable copy/roprhome.pdf

(Big file to download though)

Thanks, that is a very interesting document. Putting it (Absolute block between Steel Works and Beeston as the Planner says) together with the distance (9 miles 10 ch) and speed limits from the SA we get something like 8 minutes running time, so 10 minute headways if I have understood it right, and better than I thought, but still not ideal.
It's quite a palaver to work out where the headway "pinch points" are - the first time you do it anyway. I guess train planning organisations hold the results and just update any that need it from changes.

 

[DarloRich]

Following from the topic below, why do they single track when it's already doubled? What's the benefit?

https://www.railforums.co.uk/threads/singling-a-line.177866/

Really? The benefit of turning a little used line into a single should be obvious, surely. I am not trying to be difficult but rather obviously the main driver is to save money through reduced maintenance and replacement costs.

When times are hard such a decision may be the difference between a service and no service at all

 

[LNW-GW Joint]

Out of interest, what was the last line on the GB network to be singled?

Ledbury-Hereford was in about 1990 I think (coupled with a speed reduction to 65mph - it used to be 90).
Wrexham-Saltney Jn was singled at much the same time (to save money on the bridge necessary over the new A483 dual carriageway).
Double track has been expensively, but only partially, reinstated in the last year or so; the bridge section is still single.

Some routes were very lucky not to have been singled by BR, who were funded to do it (as well as saving costs).
The S&C is one (it's single over the Ribblehead viaduct), the Marches line is another.

The business case for redoubling is sometimes very weak.
Was it right to redouble Gretna-Annan, or build the Doncaster North Chord now the coal traffic has vanished?

 

[a_c_skinner]

obviously the main driver is to save money through reduced maintenance and replacement costs.

This is a completely genuine question: how much does it save? Double track vs single with twice the useage? I have heard it said that the savings were largely accounting only savings but have no idea if that is true, but as the remaining track is used twice as much it seems plausible.

 

[DarloRich]

This is a completely genuine question: how much does it save? Double track vs single with twice the useage? I have heard it said that the savings were largely accounting only savings but have no idea if that is true, but as the remaining track is used twice as much it seems plausible.

No idea. I have only ever been involved in a full removal. Logically halfing the infrastructure must lead to some saving if only in parts and time. That must release resources to use elsewhere

 

[Bald Rick]

This is a completely genuine question: how much does it save? Double track vs single with twice the useage? I have heard it said that the savings were largely accounting only savings but have no idea if that is true, but as the remaining track is used twice as much it seems plausible.

Well it hasn’t been done for over quarter of a century, and as I mentioned earlier the accounting back then was a little, ahem, ‘imaginative’.

Nevertheless the cost saving would have been significant, both in terms of immediate renewal costs avoided, and also maintenance costs saved. Doubling the usage 9n the remaining track is largely irrelevant; again as I said earlier often the train service was reduced at the same time, and even if it wasn’t rarely was the service on the remaining track above the level where anything but the minimum maintenance was required. But even minimum maintenance costs money, and having one track halved that amount.

 

[Bletchleyite]

Every mile of track is sacred...!

I agree if a single section has been sufficient for decades but needs redoubling now then even with the benefit of hindsight it was not a bad decision. Some single sections like Dore are a major problem and redoubling is necessary. The Windermere branch is a good example of a singling that was probably a good idea. Id say it needs longer platforms and either electrification or battery / hydrogen trial much more than redoubling.

Windermere is fine - it's an example of a singling that was done in support of a specific service pattern (hourly) which is correct for the line's level of demand and it does allow that service pattern to be delivered punctually and reliably. The only point of redoubling would be if you wanted to allow for charters on the line, which is not a justifiable reason for public subsidy of such changes. Realistically if the branch gets busier the best solution is longer trains on the existing service pattern.

Similarly, Ormskirk-Preston was singled with a passing loop at Rufford, supporting the two-unit hourly service operating at the time (though further cost-cutting meant that the service was dropped to a single unit irregular one, sadly). The Island Line also ended up with the same problem - two loops were built supporting a three-unit, 20 minute frequency service which proved to be overkill. But as long as you specify the infrastructure for the service that will be needed long-term and don't fear doing the necessary work to change it if that changes, the concept works. Lausanne, for example, has a tram line which is mostly single-track! Also most of the Swiss narrow gauge lines are single with loops at stations.

St Albans was however a piece of idiocy - infrastructure inadequate for a half-hourly service, but hourly is seen as inadequate, so you get the bizarre 45 minute frequency instead, when half-hourly (2 units) peak and hourly off-peak would make most sense.

 

[Bletchleyite]

No idea. I have only ever been involved in a full removal. Logically halfing the infrastructure must lead to some saving if only in parts and time. That must release resources to use elsewhere

If the single line can then be operated one engine in steam (using train staff operation or similar) you also have a signalling saving. Past Rufford there is no signalling at all on the Ormskirk line, just a bit of wood with a metal plaque on it. Had they gone the whole hog, removed the Rufford loop and converted the crossing to AHB, they could have had no signalling at all on it and just held the train staff at Preston.

 

[yorksrob]

I think that as far as the great singling debate, I think I have least sympathy for the Western Region of British Rail. They seemed to go in more for singling long regional routes, rather than odd branch lines which would be less of an issue.

 

[Bald Rick]

St Albans was however a piece of idiocy - infrastructure inadequate for a half-hourly service, but hourly is seen as inadequate, so you get the bizarre 45 minute frequency instead, when half-hourly (2 units) peak and hourly off-peak would make most sense

I’m not sure the Abbey line was singled. I think it has always been single track. There may have Ben a loop that’s was removed, but I wouldn’t say that was singling in the sense of this thread. @ChiefPlanner will confirm.

Also the 45 minute service is only a relatively recent development, it was hourly until around 2007.

 

[furnessvale]

The business case for redoubling is sometimes very weak.
Was it right to redouble Gretna-Annan, or build the Doncaster North Chord now the coal traffic has vanished?

At the time the chord was built its traffic was guaranteed. A sudden change in government policy and a rapid and unseemly hasty cutback on coal fired power stations meant much of that traffic has gone but you would have needed a crystal ball to have foreseen it.

 

[ChiefPlanner]

I’m not sure the Abbey line was singled. I think it has always been single track. There may have Ben a loop that’s was removed, but I wouldn’t say that was singling in the sense of this thread. @ChiefPlanner will confirm.

Also the 45 minute service is only a relatively recent development, it was hourly until around 2007.

(1) Always single track bar a passing loop at Bricket Wood (and a long freight only headshunt towards Watford North)

(2) the 45 min headway was in operation from electrification in the late 1980's.

 

[Tomnick]

If the single line can then be operated one engine in steam (using train staff operation or similar) you also have a signalling saving. Past Rufford there is no signalling at all on the Ormskirk line, just a bit of wood with a metal plaque on it. Had they gone the whole hog, removed the Rufford loop and converted the crossing to AHB, they could have had no signalling at all on it and just held the train staff at Preston.

...which would’ve precluded the current service pattern, where nothing’s booked to cross at Rufford but the hourly services do cross between Preston and the junction for the branch. One Train Working without a train staff over the whole branch would’ve worked though, with the single line proved clear each time by sequential operation of track circuits. I wonder whether the cost savings through abolishing the two intermediate boxes at the time might’ve paid for an extra unit (and crews) for a proper hourly service back then.

 

[Bald Rick]

(1) Always single track bar a passing loop at Bricket Wood (and a long freight only headshunt towards Watford North)

(2) the 45 min headway was in operation from electrification in the late 1980's.

Thanks Guv.

I could have sworn it was only hourly when we moved here, as the connections were standard through the day and I vaguely rememeber a bit of hoo-har when it moved to 46 mins. Cold be wrong of course.

 

[ac6000cw]

Very true, and you only need to look at the USA to see what volume of freight, or Switzerland for passengers, can be put over a single line, PROVIDED the timetable is robust.

George

...although they have (over many years) evolved the type of trains operated to get the most out of a single-line infrastructure i.e. very long trains at relatively infrequent intervals, sometimes 'flighted' together to minimise crossings and make best use of intermediate block signals. Some of the crossing loops are long enough to qualify as significant lengths of double track in the UK...

And yes, the operating precision of Swiss railways is a joy to behold (although it doesn't always work - every railway has problems sometimes), but we're pretty good at it too when we want to be.

 

[ChiefPlanner]

Thanks Guv.

I could have sworn it was only hourly when we moved here, as the connections were standard through the day and I vaguely rememeber a bit of hoo-har when it moved to 46 mins. Cold be wrong of course.

There was a short period when it went hourly off peak , but "pressure" to revert to the 46 min frequency arose. Connections really are directed towards and from Euston.

 

[Chester1]

This is a completely genuine question: how much does it save? Double track vs single with twice the useage? I have heard it said that the savings were largely accounting only savings but have no idea if that is true, but as the remaining track is used twice as much it seems plausible.

As demonstrated in this thread, the real savings are when it allows signalling to be simplified or through allowing cheap gauge clearance work and / or electrification through scewing the track down the middle. I think singling the Meir Tunnel on the Crewe to Derby line was proposed about 5 years ago to allow the line to be used for container traffic. I think it was decided there was insufficient demand for container traffic for it to be worth spending the money on extra signalling that would be necessary to offset the loss in capacity caused by a single section.

The Island Line also ended up with the same problem - two loops were built supporting a three-unit, 20 minute frequency service which proved to be overkill. But as long as you specify the infrastructure for the service that will be needed long-term and don't fear doing the necessary work to change it if that changes, the concept works. Lausanne, for example, has a tram line which is mostly single-track! Also most of the Swiss narrow gauge lines are single with loops at stations.

The Island line is a good argument for further singling. The placement of the loops combined with rolling stock being withdrawn due to age has caused an odd 40 minutely timetable. The line would be better served by 2 x 3 coach 230s (with longitudinal seating in the middle coach to allow more standing during high demand). A single line with one loop in the middle would also allow the steam railway to extend to Ryde St Johns.

 

[ChiefPlanner]

Porth - Treherbert was a singling too far - and the Ystrad Mynach loop was put in to compensate - about the most intensive bit of timetabled operation on a regional railway. (CUI of 96% or so)

The retained track was the "best" , which by the levels of investment in the South Wales valleys of the 1970's was not very good ....

 

[yorksrob]

As demonstrated in this thread, the real savings are when it allows signalling to be simplified or through allowing cheap gauge clearance work and / or electrification through scewing the track down the middle. I think singling the Meir Tunnel on the Crewe to Derby line was proposed about 5 years ago to allow the line to be used for container traffic. I think it was decided there was insufficient demand for container traffic for it to be worth spending the money on extra signalling that would be necessary to offset the loss in capacity caused by a single section.



The Island line is a good argument for further singling. The placement of the loops combined with rolling stock being withdrawn due to age has caused an odd 40 minutely timetable. The line would be better served by 2 x 3 coach 230s (with longitudinal seating in the middle coach to allow more standing during high demand). A single line with one loop in the middle would also allow the steam railway to extend to Ryde St Johns.

Would it not be better just to insert the loop in the optimum place, and retain the others in case of disruption etc ?

 

[Bevan Price]

Ledbury-Hereford was in about 1990 I think (coupled with a speed reduction to 65mph - it used to be 90).
Wrexham-Saltney Jn was singled at much the same time (to save money on the bridge necessary over the new A483 dual carriageway).
Double track has been expensively, but only partially, reinstated in the last year or so; the bridge section is still single.

Some routes were very lucky not to have been singled by BR, who were funded to do it (as well as saving costs).
The S&C is one (it's single over the Ribblehead viaduct), the Marches line is another.

The business case for redoubling is sometimes very weak.
Was it right to redouble Gretna-Annan, or build the Doncaster North Chord now the coal traffic has vanished?

Re-doubling Gretna - Annan has improved punctuality a bit. On my trips from Carlisle to Dumfries (usually several per year), it used to be common for northbound trains to be checked at Gretna, waiting for late southbound trains to come off the single line section.

 

[edwin_m]

There was some singling of the Robin Hood Line to make space for Nottingham tram. Must have been around 2000 which I think is later than any of the "most recents" suggested.

 

[Dr Hoo]

There have been a few singlings of the ‘odd’ sides of triangles in the post-BR era. Gartcosh, Cowlairs, Maindee spring to mind. Lenton curve at Nottingham possibly the most recent?

 

[Grumpy]

Was it right to redouble Gretna-Annan, or build the Doncaster North Chord now the coal traffic has vanished?

That would be the same Doncaster North Chord used for Immingham-Drax biomass trains of which for example there were 31 trains run (incl. returns) on 6 Feb.
Seems a reasonable use.

 

[furnessvale]

And yes, the operating precision of Swiss railways is a joy to behold (although it doesn't always work - every railway has problems sometimes), but we're pretty good at it too when we want to be.

I remember in the late 1960s or early 1970s we had a phase of having a "punctuality day" every so often when we tried to run the trains on time.

I don't think I was too popular when I said, aren't we supposed to do that EVERY day!

 

[30907]

I think that as far as the great singling debate, I think I have least sympathy for the Western Region of British Rail. They seemed to go in more for singling long regional routes, rather than odd branch lines which would be less of an issue.

True, but all the routes concerned (Oxford-Worcester, Swindon-Kemble, Salisbury-Exeter, Risborough-Aynho) carried a basic 2-hourly service in the mid 60s, with no immediate prospect of growth, and partial singling was a reasonable solution.

 

[Bletchleyite]

...which would’ve precluded the current service pattern, where nothing’s booked to cross at Rufford but the hourly services do cross between Preston and the junction for the branch.

True, I suppose you'd have had to have the train staff given/taken at Midge Hall (as the token for Midge Hall-Rufford presently is) and so only save one box rather than both. That said, there would still have been a saving because the electric token equipment could be decommissioned.

I did post here a question as to why the northern part isn't train staff rather than token, but train staff could cause issues for the last train if passing at Rufford as there would need to be two consecutive northbound trains on the northern section.

 

[yorksrob]

True, but all the routes concerned (Oxford-Worcester, Swindon-Kemble, Salisbury-Exeter, Risborough-Aynho) carried a basic 2-hourly service in the mid 60s, with no immediate prospect of growth, and partial singling was a reasonable solution.

In terms of Salisbury - Exeter, they did close the Seaton branch, so they weren't exactly growing traffic #