Single line sections that would benefit from becoming multitrack?

[Ashley Hill]

I think the Exmouth branch is worthy of mention, if it hasn't been already. Historically the line was double track from Exmouth Junction to Topsham (inclusive), with 4 platforms at Exmouth. Re-doubling Exmouth Junction to Polsloe Bridge, preferably with a double lead junction and two platforms, would help to stop SWR and ECS GWR trains being held up in the Exmouth Junction area. I'm not sure if extending the double track at Topsham or doubling at Exmouth (i.e. a second platform) would be better for the service.

Several expensive factors would prevent re-doubling to Topsham. The old Polsloe Bridge down platform is beyond help,it would need a total replacement and the upside isn’t in the rudest of health. Digby and Newcourt were only built for single line with no obvious signs of any provision for redoubling. The bridges over the M5 and A379 are only single track. The best one could hope for is as you say a double junction at Exmouth Jct with a short section of line towards Polsloe allowing trains to clear the junction.

 

[JLH4AC]

Between Grimsby Town & Cleethorpes there is a single track section which could do with being a double track but difficult with the land & the housing nearby.

Redoubling the line between Grimsby Town and Cleethorpes would be great for improving services between Lincoln and Grimsby/Cleethorpes.

The former trackbed is mostly unaffected by development, most of it being empty land that Network Rail put some signalling equipment in that will not be needed when doubled or can be relocated with more care to their placement. It is just the section between Grimsby Docks and New Clee that the surrounding development will be a real issue, but due to the amount of vacant land and poor-quality buildings in the surrounding area, redevelopment is needed near the tracks anyway. It is the two single-track bridges across major roads, one single-track bridge across a minor road, and a road bridge that might need to be rebuilt to allow the replacement of one of the bridges over the major road that would be the most pressing issue relating to redoubling the line.

 

[gingertom]

Ladybank to Hilton Jn sets the number of paths. Redoubling would enable significant service improvements. Even dynamic passing loops would help, a reopened station at Newburgh perhaps?

 

[och aye]

Ladybank to Hilton Jn sets the number of paths. Redoubling would enable significant service improvements. Even dynamic passing loops would help, a reopened station at Newburgh perhaps?

Could a station at Bridge of Earn (perhaps even Abernethy) be viable if Newburgh was to get it's station back?

 

[Dr Hoo]

Could a station at Bridge of Earn (perhaps even Abernethy) be viable if Newburgh was to get it's station back?

Depending on how extensive the doubling or dynamic loop(s) was, new stations might require two platforms with a significant increase in (further) costs. Plus electrification too?

‘Viable’ is a very high bar on all routes serving rural areas.

 

[30907]

This reminds me of the Little North Western, which many would have expected to have been singled at some stage, but which has retained double track.

Singling would have required a loop somewhere, and Wennington (the last box to survive) wouldn't have been a sensible place.
It was one thing in the 90s to have a timetable based on RR using a "notional single line," another to enforce that in (semi)perpetuity!

 

[Horizon22]

The single bore between Heathrow T2/3 and Terminal 4. It isn't really designed for a 4tph operation that it has now.

 

[JonathanH]

The single bore between Heathrow T2/3 and Terminal 4. It isn't really designed for a 4tph operation that it has now.

Surely it was explicitly designed for a 4tph operation, as that is how Heathrow Express started before Terminal 5 was built?

Wasn't there some speculation in another thread that Terminal 4 will shut at some point?

 

[Class15]

Assuming we're not counting some ridiculous and short sighted turning of double lead junctions into single leads under the latter days of BR (Haughley Jn, Midcalder Jn, Dore station) then the list is actually quite short.

Haughley Jn seems particularly stupid to me. What was the justification?

It has made freight traffic out of Felixstowe more difficult, and forced diesel-worked freight trains to go via Stratford and Camden Road (obviously electric freights need to go via that route for other reasons - no wires!)

 

[dk1]

Haughley Jn seems particularly stupid to me. What was the justification?

It has made freight traffic out of Felixstowe more difficult, and forced diesel-worked freight trains to go via Stratford and Camden Road (obviously electric freights need to go via that route for other reasons - no wires!)

Unfortunately that was the sad state of BR in the early 1980s.

 

[Magdalia]

Haughley Jn seems particularly stupid to me. What was the justification?

Single lead junctions are cheaper to install and maintain.

In the early 1980s the daytime passenger traffic at Haughley was:

1 tph London-Norwich
1 tp2h Ipswich-Cambridge
3 tpd Ipswich-Peterborough

Felixstowe intermodal traffic was much less significant, the container port was still almost new, and the most important freight trains through Haughley were speedlink going to and from Parkeston.

At that time the level of traffic was roughly half what it is now and did not justify a more expensive double lead junction.

 

[Class15]

Unfortunately that was the sad state of BR in the early 1980s.

Single lead junctions are cheaper to install and maintain.

In the early 1980s the daytime passenger traffic at Haughley was:

1 tph London-Norwich
1 tp2h Ipswich-Cambridge
3 tpd Ipswich-Peterborough

Felixstowe intermodal traffic was much less significant, the container port was still almost new, and the most important freight trains through Haughley were speedlink going to and from Parkeston.

At that time the level of traffic was roughly half what it is now and did not justify a more expensive double lead junction.

Thank you. Perhaps short-sighted, then, but maybe not as ridiculous as I thought.

Canonbury Curve has to be another contender as freight trains frequently have to sit on it to wait for Godot a North London line path, thus blocking freights in the other direction. I remember hearing it was due to the tunnel being too small for two electrified lines, but I’m afraid I don’t remember where (sorry!)

 

[Magdalia]

Canonbury Curve has to be another contender as freight trains frequently have to sit on it to wait for Godot a North London line path, thus blocking freights in the other direction. I remember hearing it was due to the tunnel being too small for two electrified lines, but I’m afraid I don’t remember where (sorry!)

I'm old enough to have done the Finsbury Park-Canonbury line on diverted Cambridge-Liverpool Street trains, in the days of diesel traction.

As its name implies, Canonbury tunnel is at the Canonbury end, the south end portal can be seen from the North London line. The south end of the tunnel is on quite a tight curve so it sounds plausible for it to be much easier and cheaper to electrify as a single line.

I don't think that the level of traffic justifies doing anything about it now.

 

[Zomboid]

Weren't the northern tracks of the NLL just for freight at that time? Would have been much less of an operational headache when the passenger trains were much less frequent and running on the DC lines.

 

[Falcon1200]

Single lead junctions also allow trains to reverse at the location, which double junctions with diamond crossings do not.

 

[Zomboid]

I never quite understood the economy of a single lead junction (which has 4 switches) as opposed to a double lead with a crossover, which also has 4 switches.
The double lead is a bit longer, but at places like Haughley there doesn't seem to be a huge account constraining that it just seems to be a conscious decision was taken to make things harder than they need to be. I'm sure there's a reason buried in the original design documentation, but looking at it from afar it's one of those "what were they thinking?" situations.

 

[MarkyT]

I never quite understood the economy of a single lead junction (which has 4 switches) as opposed to a double lead with a crossover, which also has 4 switches.
The double lead is a bit longer, but at places like Haughley there doesn't seem to be a huge account constraining that it just seems to be a conscious decision was taken to make things harder than they need to be. I'm sure there's a reason buried in the original design documentation, but looking at it from afar it's one of those "what were they thinking?" situations.

There are places where a single lead configuration can be faster for the turnout routes. Simpler than both is the traditional double junction with a diamond, which as long as it's fixed and not switched, only has two turnouts.

 

[The Planner]

There are places where a single lead configuration can be faster for the turnout routes. Simpler than both is the traditional double junction with a diamond, which as long as it's fixed and not switched, only has two turnouts.

Most track engineers want them split out these days with no fixed crossings. In the case of single leads you end up moving the crossover, or divergence, anyway if you want to fix it.

 

[MarkyT]

Most track engineers want them split out these days with no fixed crossings. In the case of single leads you end up moving the crossover, or divergence, anyway if you want to fix it.

A ladder form double lead is clearly best, but the longer footprint sometimes doesn't fit within the railway boundary. Note signal engineers really don't like switched diamonds! They're a pig to keep in adjustment and very susceptible to detection failures from expansion in changing temperatures. That's why they were some of the first locations where white painting of rails was employed.

If the crossing angle is suitable, I'd always suggest consideration of a fixed diamond arrangement to make the whole junction simpler and more reliable. Not always possible clearly. The double junctions for the Bacon Factory curve at Ipswich had to be switched diamonds, necessary within the constrained geometry to maintain speed of the the long intermodals through the turnouts and ensure they have clear standage on the curve.

 

[Horizon22]

Surely it was explicitly designed for a 4tph operation, as that is how Heathrow Express started before Terminal 5 was built?

Wasn't there some speculation in another thread that Terminal 4 will shut at some point?

For a long time it was an inter-terminal shuttle. It may well have sufficed back then, but the issue is that with 10tph overall to the airport now, even a tiny delay means a train either arriving or departing often has to be held.

For instance a delay from Terminal 5 to Terminals 2/3 might delay a train that has just departed from T4. But the subsequent arrival to T4 has to wait as it has nowhere to go.

 

[aron2smith]

West of England line between Salisbury and Exeter, the single sections always causes delays.

Weymouth to Yeovil Pen Mill would be a lot better as a double railway too. Rail connections between Dorset and Devon and the rest of the South West need improving.

 

[yorksrob]

West of England line between Salisbury and Exeter, the single sections always causes delays.

Weymouth to Yeovil Pen Mill would be a lot better as a double railway too. Rail connections between Dorset and Devon and the rest of the South West need improving.

I do agree with this. And extend it to Plymouth via Okehampton.

 

[aron2smith]

I do agree with this. And extend it to Plymouth via Okehampton.

Definitely. The 118 bus between Okehampton and Tavistock gets quite decent ridership now for a part of the country that is 2 smallish towns and little more than villages along the way, the potential is definitely there!

 

[Railwaysceptic]

I'm old enough to have done the Finsbury Park-Canonbury line on diverted Cambridge-Liverpool Street trains, in the days of diesel traction.

I'm old enough to have used it every day going to and from work when Broad Street Station was still functioning.

 

[AndrewE]

I would offer the single-track on the southern slow lines approach to Crewe Station, 4 track all the way from Stafford, 13 lines in the station (every single one accessible from the up and down fast and slows) and you have a pinch point immediately S at S Junction.

 

[Helvellyn]

Alton to Farnham would be a fairly promising candidate for re-doubling.

With the loop at Bentley and two platforms for terminating trains at Alton is it really a major constraint? I think Farnham-Bentley was considered for doubling if the Bentley-Bordon line had re-opened. Also, whilst Farnham-Alton was built for double track was it actually ever double apart from at the stations?

 

[Zomboid]

Also, whilst Farnham-Alton was built for double track was it actually ever double apart from at the stations?

Yes, singled in the 80s.

 

[supervc-10]

West of England line between Salisbury and Exeter, the single sections always causes delays.

Having grown up along this route, and with my parents still living down there, it so frustrating. The number of times I've sat in Tisbury car park waiting to collect a relative off the westbound train, which has been sitting in the loop, waiting for an up service to arrive from Yeovil/Exeter. Once there's a single delay, the whole thing gets messed up for the rest of the day it feels. So frustrating.

Needs some electrons, too....

 

[jimm]

Almost more frustrating are the missed opportunities to re-double some of these lines. Most of Pinhoe to Honiton should have been done when Cranbrook was built. Likewise Worcestershire Parkway was built with passive provision for a second track and platform on the Cotswold line when it would have been much easier to get it added at the same time as the station.

Unless and until the Worcester area ceases to be a live-action Victorian signalling museum, no one is going to be adding anything there, including altering the layout at and around Norton Junction - whether that is redoubling through to Evesham, reinstating a double-lead junction with a second track out to a point east of Parkway or installing a platform loop for a second high-level platform while retaining the single-lead junction.

In the redoubling vein, Wolvercot Junction - Charlbury East and Evesham - Norton Junction would help delays on teh Cotswold Line. Currently, only 3 tph can run between Wolvercot and Charlbury as the timings on Real Train Times shows it takes approx 16-17 mins to cover this section. The northbound and Southbound services generally pass between Ascott-underWychwood and Shipton,but any late running northbound can screw the southbound as to it's presentation time at Wolvercot, which is the main issue on the route.

Just a quick note re naming here - Wolvercot Junction became Wolvercote North Junction when the Oxford area resignalling scheme was implemented in 2018. Wolvercote South is where the reinstated down loop line from Oxford station rejoins the down Banbury main line just past the overbridge for the road into the village of Wolvercote.

 

[stevieinselby]

The single platform at Malton is effectively an ill advised singling, does anything use the other track at all?

A big advantage of that is that it means Malton station is fully accessible without the need for expensive and unreliable lifts being added and eastbound passengers having to schlep over a footbridge.
With the line only being used by 1 train per hour each way, there is no meaningful disadvantage to having a singled platform. Even if the second train per hour that Northern were lining up had come in, it still shouldn't be a problem to schedule the services so that they don't clash at that specific point on the otherwise double-track route.