Double track line rationalisation cost/benefits

[slipdigby]

Evening all!

Theoretical question, assume we have a 100km double track railway that is running well below it's operational capacity in terms of services. Assuming costs of making any changes are zero and paid for by a 3rd party, at what level of service does conversion to single line with passing loops become a better option than retaining double track from a purely maintenance and renewals perspective?

An alternative way to look at this may be to ascertain the relative costs of 1km of single plain line vs 1 SEU (signal equivalent unit, do we still use these?) and turnout.

Thanks in advance!
Slip

 

[Bald Rick]

Evening all!

Theoretical question, assume we have a 100km double track railway that is running well below it's operational capacity in terms of services. Assuming costs of making any changes are zero and paid for by a 3rd party, at what level of service does conversion to single line with passing loops become a better option than retaining double track from a purely maintenance and renewals perspective?

An alternative way to look at this may be to ascertain the relative costs of 1km of single plain line vs 1 SEU (signal equivalent unit, do we still use these?) and turnout.

Thanks in advance!
Slip

Depends on how many loops, how long they are, and where they are.

2 x 49km loops are going to have much more capacity than 1 x 1km loop.

 

[Efini92]

Is there much saving in having loops as opposed to just leaving it double tracked? Surely point work is more expensive to maintain than just plain line?

 

[MadMac]

In the 80s, there was a proposal to single south of Kilmarnock to Annan which got as far as relay rooms being built and cables/routes being installed. BR realised they’d made a serious mistake due to increasing service proposals, and while trying to find a way out of it, the contractor came along and admitted that they had seriously underestimated the cost and asked to be let out of the contract. Win all round! Point being that there comes a point where any savings do indeed get outweighed by increased maintenance.

 

[slipdigby]

Depends on how many loops, how long they are, and where they are.

2 x 49km loops are going to have much more capacity than 1 x 1km loop.

Touche!

To clear up any semantics, I was thinking bare minimum to allow services to cross.

Is there much saving in having loops as opposed to just leaving it double tracked? Surely point work is more expensive to maintain than just plain line?

This is pretty much the exam question I was (poorly) getting at - at very broadly what point does the cost of additional expensive turnouts and signalling outweigh the savings in plain line? Is there a ballpark ratio?

Ta!
Slip

 

[PGAT]

Singling tracks is usually a bad idea. You still have to pay loads of money to remove the second tracks and resignal the area. It also becomes a bottleneck and a pain in the stomach for future generations to try and redouble it again.

 

[JonathanH]

It also becomes a bottleneck and a pain in the stomach for future generations to try and redouble it again.

However, it can save money on the cost of keeping the full width of embankments secure, and allow the track to be slewed to the centre of the formation for faster speeds.

For the avoidance of doubt I am not advocating it, just pointing out a benefit. The constraint on the timetable and capacity is a distinct disadvantage.

 

[brad465]

Singling tracks is usually a bad idea. You still have to pay loads of money to remove the second tracks and resignal the area. It also becomes a bottleneck and a pain in the stomach for future generations to try and redouble it again.

Have there been any major singling of existing routes post-Beeching (apart from maybe Ribblehead viaduct to help reduce strain on the viaduct)? I know the reinstatement of the Border's railway to Tweedbank is an example of reopening a route but largely to single track only.

However, it can save money on the cost of keeping the full width of embankments secure, and allow the track to be slewed to the centre of the formation for faster speeds.

I did think of this and know of a few routes this has been done, but would presumably only be beneficial to the fastest largely single line routes. Routes like the West of England mainline (max 85mph over single sections) and the Cotswold line (100mph max) I can certainly see it, but not on a number of slow branches.

One example of singling that I don't understand is Moreton-Dorchester West on the SWML. It's relatively short, so can't see how it brought much cost saving, while presumably can cause some problems still with delayed services. I could understand it more if they singled it further, such as for most of the route between Dorchester and Poole, and had at least one passing loop (probably Wareham) in between.

 

[61653 HTAFC]

Have there been any major singling of existing routes post-Beeching (apart from maybe Ribblehead viaduct to help reduce strain on the viaduct)? I know the reinstatement of the Border's railway to Tweedbank is an example of reopening a route but largely to single track only.

Stocksmoor to Huddersfield was singled in the 1980s after Clayton West closed. Later the remaining line was slewed in places to increase speeds, and it reduced the strain on Paddock Viaduct. Does mean we need an additional loop if we want to go 2tph though.

On Ribblehead, I'd read somewhere that singling had some negative effects too, by shifting the gravity centre of loads over it, but that could be a myth.

 

[Taunton]

Evening all!

Theoretical question, assume we have a 100km double track railway that is running well below it's operational capacity in terms of services. Assuming costs of making any changes are zero and paid for by a 3rd party, at what level of service does conversion to single line with passing loops become a better option than retaining double track from a purely maintenance and renewals perspective?

Unfortunately the costs of the works are not zero. Back in the 1960s there were Track Rationalisation Grants made available by the Min of T to BR to do such work (after quite some lobbying), mainly driven by the simplistic costing systems of the era, which just took the total overall civils costs and divided this by the number of track miles to give a "cost per track mile". Which was a pretty nebulous figure. There were so many issues with this it is surprising a more appropriate evaluation approach was not followed.

- Costs of earthworks and bridge etc maintenance are not particularly dependent on how many tracks remain on the formation.
- With minimal provision for passing, the timetable becomes fossilised. Yet history shows that timetables do not stay constant over time, services rise, fall, are accelerated so trains pass in different places, retimed for different connections, etc.
- Although only one track remains, it is now handling double the traffic/tonnage, and experience shows that quite a proportion of maintenance cost is in proportion to the tonnage handled.
- The usual issues about inability to handle delays, breakdowns, and other events as well as when there are two tracks.

That's before safety is considered. Of course, trains respond to signals, so should not be any issue. Except history shows otherwise. Where this really came in was when single lead junctions, a comparable approach, were introduced, because diamond crossings were high maintenance for the civils. There followed a whole string of head-on collisions on such layouts, given that the traditional safety aspect of Flank Protection necessarily went as well, apparently to quite some surprise of rail senior management, but in all honesty they should have seen it coming.

 

[Magdalia]

Have there been any major singling of existing routes post-Beeching (apart from maybe Ribblehead viaduct to help reduce strain on the viaduct)?

Newmarket-Dullingham was singled in 1978 after Newmarket signal box was lifted off its foundations by a whirlwind.

Coldham Lane-Dullingham was singled in 1982 as part of the Cambridge PSB resignalling.

Littleport-Downham and Magdalen Road-Kings Lynn were singled in the 1980s.

Trowse Swingbridge was singled as part of Norwich resignalling in 1986(?)

Around that time there was a proposal to single Haughley-Trowse.

When was Hever-Uckfield singled?

I know the reinstatement of the Border's railway to Tweedbank is an example of reopening a route but largely to single track only.

The tunnel under the runway at Stansted Airport is single track, as is the Stansted North Curve.

 

[brad465]

When was Hever-Uckfield singled?

I can't find exactly when but I'd guess 1985 when Tunbridge Wells-Eridge (now Spa Valley heritage railway) closed. The route does have a dynamic loop centred on Crowborough so it could be argued it was singled between Hever and Crowborough with a passing loop at Ashurst, and between the southern end of that loop and Uckfield.

EDIT: Hastings Diesels Ltd claim it was singled in 1990.

 

[Mcr Warrior]

When was Hever-Uckfield singled?

January 1990, apart, of course, for the long passing loops.

 

[Sir Felix Pole]

On the Cornish Main Line Burngullow to Probus was singled in 1986 - now happily reversed. Long Rock to Penzance was singled in 1974 (in preparation for the HST depot) and Largin and St. Pinnock viaducts had been singled in 1964. On the Devon side St. Budeaux (FR) to the Royal Albert Bridge was singled in 1974 with the extension of the Plymouth PSB operating area.

In the '60s singling Liskeard right through to Penzance was even contemplated, with the bizarre proposal of closing St.Erth station and running St. Ives branch trains to Hayle on the spare second track.

 

[AF91]

Speaking as a train planner, I'd be dead against singling double track railway. Single lines eat into any sort of flexibility available to the planners and if not limited to self contained services can end up dictating large parts of a train plan.

 

[zwk500]

The only place where it would really make sense is at the end of a branch to turn it into a One Train in Section. Then you only need 1 turnout and 1 axle counter or 2 track circuits to monitor occupancy. This saves on the cost of continuous TC/AD equipment and all the signals on both lines, together with the crossover you'd inevitably need at the final station anyway. However it doesn't make sense to do this to existing lines as the cost of the intervention will be massive and the saving of the maintenance modest.

Speaking as a train planner, I'd be dead against singling double track railway. Single lines eat into any sort of flexibility available to the planners and if not limited to self contained services can end up dictating large parts of a train plan.

Agree (as a former train planner).

 

[Surreytraveller]

Speaking as a train planner, I'd be dead against singling double track railway. Single lines eat into any sort of flexibility available to the planners and if not limited to self contained services can end up dictating large parts of a train plan.

Planners still manage to screw it up despite having self-contained services, by having crews working other services

 

[High Dyke]

Skegness line, in sections between Sleaford and Sibsey. This has its pinch points due to the scheduling.

 

[Falcon1200]

Speaking as a train planner, I'd be dead against singling double track railway.

Agree (as a former train planner).

Agree also (as a former Controller). Fortunately some of the single line sections in my area were actually redoubled during my career, eg Lugton/Kilmarnock (partly) and Annan/Gretna Jc. However there are cases where limited singling has had so-far unmentioned benefits, such as being able to electrify with OLE, eg through the Barncluith Tunnel at Hamilton, or (a unique case?) allowing normal stock to run through narrow tunnels, as on the Hastings Line.

 

[snowball]

Have there been any major singling of existing routes post-Beeching (apart from maybe Ribblehead viaduct to help reduce strain on the viaduct)? I know the reinstatement of the Border's railway to Tweedbank is an example of reopening a route but largely to single track only.

The Britannia bridge was singled as part of its reconstruction after the 1970 fire.

 

[zwk500]

Agree also (as a former Controller). Fortunately some of the single line sections in my area were actually redoubled during my career, eg Lugton/Kilmarnock (partly) and Annan/Gretna Jc. However there are cases where limited singling has had so-far unmentioned benefits, such as being able to electrify with OLE, eg through the Barncluith Tunnel at Hamilton, or (a unique case?) allowing normal stock to run through narrow tunnels, as on the Hastings Line.

These cases are rare though, and especially with OLE in tunnels (Abbeyhill tunnels next to Edinburgh were singled for OLE, IIRC), track lowering can often be practical.
The Hastings line was a strange situation where the original contractors had skimped the brickwork and so emergency strengthening had reduced the bore size. The only option would have been to reborn the tunnels which wasn't remotely feasible to fund in the mid 80s.

 

[edwin_m]

Kettering to Corby was singled in the late 1980s. Blackpool South and Colne were fairly late on too.

 

[Greybeard33]

I believe Ash Bridge Junction to Denton Station Junction, on the Heaton Norris to Denton line, was also singled in the late 1980s, during construction of the southern section of the M66 motorway (now part of the M60). This enabled the long diagonal bridge over the motorway to be built with the deck single track width.

Edit: I think another example of singling to save on road building costs is Cheadle Village Junction to Sharston Junction on the Stockport to Altrincham line. This has two single track underbridges built in the 1970s over slip roads of the M63 (now also part of the M60). At the time the line was freight only, but now it is used by Mid Cheshire line passenger services and the single track section is a constraint on timetable planning (together with the single track section through Navigation Road, where Metrolink took over the other half of the formation in the early 1990s).

 

[Backroom_boy]

I beleive much of the drive for singling to 'reduce costs' is down to reducing the networks liability costs as seen by the Treasury. Eg. Single track has a lower value than double track therefore the book value of maintenance liability is lower according to the accounting rules the Treasury follows.

 

[Snow1964]

I believe Ash Bridge Junction to Denton Station Junction, on the Heaton Norris to Denton line, was also singled in the late 1980s, during construction of the southern section of the M66 motorway (now part of the M60). This enabled the long diagonal bridge over the motorway to be built with the deck single track width.

Edit: I think another example of singling to save on road building costs is Cheadle Village Junction to Sharston Junction on the Stockport to Altrincham line. This has two single track underbridges built in the 1970s over slip roads of the M63 (now also part of the M60). At the time the line was freight only, but now it is used by Mid Cheshire line passenger services and the single track section is a constraint on timetable planning (together with the single track section through Navigation Road, where Metrolink took over the other half of the formation in the early 1990s).

Sometimes these get fixed when traffic grows, a second bridge over M5 was added near Avonmouth few years ago to allow double track to be restored.

There is a signaling north of Fareham. The line originally had a single bore tunnel, late a deviation was built that was double, but now back to using the tunnel with deviation line closed (think this happened in 1960s)

 

[TheDavibob]

Littleport-Downham and Magdalen Road-Kings Lynn were singled in the 1980s.

Given the bits of Ely-Kings Lynn that were singled were done to simplify electrification (i.e. put masts into the embankment), would singling the lines still be considered if the (double-track) lines were being electrified today?

 

[Tester]

There is a signaling north of Fareham. The line originally had a single bore tunnel, late a deviation was built that was double, but now back to using the tunnel with deviation line closed (think this happened in 1960s)

Even more complicated - for a time northbound was via the deviation, with southbound through the tunnel.

The deviation is now a path.

 

[Magdalia]

Given the bits of Ely-Kings Lynn that were singled were done to simplify electrification (i.e. put masts into the embankment), would singling the lines still be considered if the (double-track) lines were being electrified today?

But Ely North Junction-Littleport and Magdalen Road-Kings Lynn are still double track, they managed to put the OHL up there.

River bridges could be an issue though. I'm fairly sure that the bridge over the River Ouse between Hilgay and Denver would have needed to be replaced for doubletrack OHL. I'm less sure about the bridge over the River Nar at St Germans. Neither of the remaining double track sections have significant river crossings.

 

[tbtc]

I’m not suggesting we single any existing lines (maybe close some, sure, but single tracking can be a lot of expense just to save small annual sums so feels fairly pointless)

However, there may be examples where you have a branch line that isn’t realistically going to ever demand more than the current service provision (e.g. Burnley to Colne won’t ever need more than an hourly service, there’s no freight, it’s a dead end with no junctions beyond the chord at Burnley, it’s just a glorified siding which will only ever have “one train in steam”)…

…on that branch we have a station like Wennington (which is on the double tracked Bentham line). At Wennington right now, services are unable to call in one direction because the footbridge is knackered. So we are running a replacement bus service and will no doubt spend tens of thousands of pounds on repairing the bridge (because nothing is ever cheap).

The problem is that Wennington only gets half a dozen departing passengers a day (a lower number than the eight trains a day in each direction scheduled to stop there).

So I could see the logic in someone deciding that if we had a station like Wennington on a branch like the Colne route then it’d be better to have single track (with everything serving one platform) than rebuilding a footbridge to a second platform

Clearly that’s just a hypothetical case (the Colne line was singled some time ago, Wennington is on another route entirely), but this seems to have been the decision on routes like the (much busier) double track Durham Coast line, where I guess someone at BR decided that it’d be “better” to install points at Hartlepool for everything to serve the western platform than to refurbish the eastern platform (so whilst the line remained double track, all southbound passenger services crossed over to serve the northbound platform instead)

But such cases are thankfully rare and we live in more enlightened times than the penny pinching Hartlepool example

However, there may be examples in the future where a contractor quotes such a huge sum to repair the crumbling “Platform 2” at a station (including footbridge , lift, security concerns etc) that Network Rail decide to stick in a couple of points and focus everything on “Platform 1”

The problem is how you ever reverse such a decision - I think this calls for a Penryn style solution!

Have there been any major singling of existing routes post-Beeching (apart from maybe Ribblehead viaduct to help reduce strain on the viaduct)?

I can’t think of any “major” (i.e. long distance) examples other than those cited by others on the thread

But one frustratingly short one in this neck of the woods was British Rail’s 1980s decision to replace the chord at Dore with single track (it’s only a short section but it has huge regional consequences)

Often there may be merits to a single track lead at a junction (as well as reasons not to) but in this case it’s meant decades of reliability problems and the service to this suburban station being severely limited

BR’s decision to have the one remaining platform on the single track section between the double track MML and the double track Hope Valley line, so the “fast” services on the long distance lines mean there’s very little scope to stop anything at Dore because a one minute dwell is going to eat up a lot of capacity in the opposite direction

The Hope Valley line also has a single track chord near Hazel Grove, so everything from South Yorkshire to Greater Manchester feels set in stone in the timetable with very little flexibility, which is a huge problem when you are dealing with a conflict like a Liverpool to Norwich train that might clash with a long/ heavy Cement train - planners lack the ability to tweak the paths by a couple of minutes because the timings at the two single track chords feel set in stone (the line is complicated enough given the gradients/ Peak District weather/ long tunnels etc)

 

[CyrusWuff]

Have there been any major singling of existing routes post-Beeching (apart from maybe Ribblehead viaduct to help reduce strain on the viaduct)?

Probably stretching the definition, but Princes Risborough - Aynho Junction was singled in 1968, with Beaconsfield losing its through lines in 1973, and Gerrards Cross following as late as 1989.

This was redoubled between Princes Risborough and Bicester North (along with construction of additional platforms at Princes Risborough and Haddenham & Thame Parkway) in 1998, and between Bicester North and Aynho Junction in 2001, as part of Chiltern's "Project Evergreen."