Lines which could do with improved signalling headways/more aspects

[brad465]

What lines have the strongest case for increasing the number of signals along it, without necessarily having any other changes to the infrastructure?

Two I can think of are:

- Castle Cary-Cogload Jct: currently 2-aspect and has a very long block between just west of Castle Cary and Somerton. It's not uncommon in the down direction for a fast train to catchup to a semi-fast ahead of it, even if they are still technically 7-8 minutes ahead. Making this 3-aspect, or at the very least adding another one or two blocks, would increase capacity and improve resilience.

- Maidstone East line: currently 3-aspect, but the blocks are notably long, possibly because it's a core freight route with no freight speed differentials. This is a particular problem in the peaks (where 4tph run at uneven intervals) and/or when a freight train traverses at certain times. I think this could do with some 4-aspect sections, especially around Otford and Maidstone East, and/or shrinking the signal blocks and having something like a 50-55mph freight limit (they hardly reach the 70-80mph limit anyway), similar to Swanley-Otford.

 

[Class15]

- Castle Cary-Cogload Jct: currently 2-aspect and has a very long block between just west of Castle Cary and Somerton. It's not uncommon in the down direction for a fast train to catchup to a semi-fast ahead of it, even if they are still technically 7-8 minutes ahead. Making this 3-aspect, or at the very least adding another one or two blocks, would increase capacity and improve resilience.

Completely agree. Every time I head down this line my train seems to get stuck behind a semi-fast. Extra signals are needed.

 

[AndrewE]

I would offer the S end of the WCML, resignalled to allow 140mph but (only/ currently) used at 125. Shorter signal sections would give shorter headways and more frequent trains, hence more capacity.

 

[The Planner]

I would offer the S end of the WCML, resignalled to allow 140mph but (only/ currently) used at 125. Shorter signal sections would give shorter headways and more frequent trains, hence more capacity.

Its on a 3 minute planning headway now, with a technical headway of around 75 seconds. You are only going to make it a performance nightmare and remove any of the Euston sponge by shoehorning more trains in to the platforms. 140 doesn't give you anything meaningful either if post HS2 you are stopping at Watford and Milton Keynes. Its one of the last lines I would touch. You sort north of Crewe out first if you are doing anything WCML.

 

[Topological]

Unlikely to be very high up the list, but a few more blocks on the Marches would be nice. Some of the blocks are very long. Even if it was just between Newport and Hereford to allow more Cardiff locals to run then it would be a start. One of the longest blocks is in that stretch.

Most of the lines I know well would benefit more from extra loops, points and platforms. Those would need signals, but do not meet the criteria of the thread.

 

[NCT]

What's the 'science' behind the technical headway / planning headway differential?

 

[jonnyfan]

The Mid-Cheshire line could do with an intermediate block section between Plumley West and Mobberley, it's a long section between those two signal boxes. It's quite often to find your service held at Plumley West heading towards Mobberley following a slightly delayed service, so it could boost reliability on the line and allow some additional services in the future.

 

[jfollows]

What's the 'science' behind the technical headway / planning headway differential?

I guess the former is the headway possible running at full line speed on clear signals. For the WCML I guess that it’s about 2 minutes, so the planning headway is longer than this.

 

[08221]

The North Staffs line between North Stafford junction and Stoke.

Would increase capacity as well as allowing trains to be run on Sunday mornings.

 

[The Planner]

What's the 'science' behind the technical headway / planning headway differential?

Its just an agreed buffer between the two signed off between NR and operators. There are various things that cannot be incorporated easily such as read through. In the past it has been as simple as taking the technical value and adding a minute on. You also consider timing points, the longest signal section, length and speed of the traction, stopping pattern as many areas will have multiple planning headways for the same section.

== Doublepost prevention - post automatically merged: 28 Dec 2025 ==

The North Staffs line between North Stafford junction and Stoke.

Would increase capacity as well as allowing trains to be run on Sunday mornings.

You could run on Sunday mornings now if someone wanted to staff the boxes.

Agree with other suggestions as well such as the Marches and Castle Cary.

 

[Gloster]

- Castle Cary-Cogload Jct: currently 2-aspect and has a very long block between just west of Castle Cary and Somerton. It's not uncommon in the down direction for a fast train to catchup to a semi-fast ahead of it, even if they are still technically 7-8 minutes ahead. Making this 3-aspect, or at the very least adding another one or two blocks, would increase capacity and improve resilience.

Castle Cary-Cogload was converted to from Absolute to Track Circuit Block in 1985 on a roughly like-for-like basis. Previously there had been intermediate boxes at Somerton and Athelney with the seven or eight minute sections either side of Somerton being the governing factor; the section between Athelney and Cogload was much shorter. This generally worked fine as, even on a summer Saturday, there was rarely more than one passenger train in each direction over the line. However, if Somerton was out of circuit, and in the last year or so of its life it had no regular signalmen and was the last priority for reliefmen, it could become a big touchy, particularly in the Up direction, if there was any disruption: you were working on an absolute minimum frequency of fifteen minutes. However, even without Somerton the number of delays was minimal unless there were severe problems somewhere and then you were probably stuffed anyway.

Like-for-like was considered adequate at the time and for the foreseeable future as no great increase in frequency was expected, nor was any new traffic considered likely. Remember, it was only a couple of years earlier that BR looked into closing Castle Cary-Cogload completely, although that was probably more of a manoeuvre to satisfy the bean-counters in the Treasury than anything else.

 

[John Webb]

Settle Junction to Carnforth, which I understand is one single block section?

 

[The Planner]

Settle Junction to Carnforth, which I understand is one single block section?

Unless there is a proposal to run more than 1tph there is no need.

 

[james_the_xv]

Worth noting that just increasing the number of aspects on signal posts while not shortening block sections will increase the headway. The number of aspects loosely correlates with line speed and braking distances (among other considerations, I'm sure someone else will have a better explaination).

Shrewsbury - Wrexham could probably do with an indermediate block or two.

Its just an agreed buffer between the two signed off between NR and operators. There are various things that cannot be incorporated easily such as read through. In the past it has been as simple as taking the technical value and adding a minute on. You also consider timing points, the longest signal section, length and speed of the traction, stopping pattern as many areas will have multiple planning headways for the same section.

Conditional double reds can be a major factor. It's the constraint on quite a lot of WCML planning values south of Crewe.

 

[The Planner]

Conditional double reds can be a major factor. It's the constraint on quite a lot of WCML planning values south of Crewe.

Thats an adjustment value for whatever move you are doing, the headway won't change, you just plan to whatever value the second train needs to be apart.

 

[Bald Rick]

I would offer the S end of the WCML, resignalled to allow 140mph but (only/ currently) used at 125. Shorter signal sections would give shorter headways and more frequent trains, hence more capacity.

It wasn’t resignalled for 140mph. It was resignalled for 125mph.

Shorter signal sections would reduce the linespeed from 125mph.

 

[devon_belle]

Low priority due to service frequency, but Dorking to Horsham could do with some more signal blocks. Headways for stopping trains are something like 9 mins, which causes problems when there are delays and/or RHTT needs to fit in.

Formerly the line had intermediate boxes at Tilehurst Lane (til 1928), Lodge Farm Intermediate (til 1938), Holmwood, Ockley (til 1965), Northwood Intermediate (til 1956), and
Warnham. Boxes at Holmwood and Warnham are obviously closed, but there are still signals there. It seems that the post-1960s semaphore layout was replaced like-for-like when colour-light signals were installed in the early 2000s.

 

[cle]

Seconding the Marches. It should be treated more of a mainline. Especially with additional services (Liverpool - Salop/Cardiff, OA via Wrexham, future adds to help Cardiff commuting, Midlands Connect routes - all touch various parts of it). - also I think a sped up Manchester and a Crewe-Cardiff additional hourly service would be better for local service.

 

[yorksrob]

I don't know what the current headway is, but presumably they could do with more between Brighton and West Worthing, given how many trains they need to shove down that route !

 

[John Webb]

Settle Junction to Carnforth, which I understand is one single block section?

Unless there is a proposal to run more than 1tph there is no need.

Is there the demand for two trains an hour which does not get fulfilled because the long block section prevents such a service?
Or is the long section left because the demand for a more frequent service isn't there?
(Just curious!)

 

[Trainman40083]

Its just an agreed buffer between the two signed off between NR and operators. There are various things that cannot be incorporated easily such as read through. In the past it has been as simple as taking the technical value and adding a minute on. You also consider timing points, the longest signal section, length and speed of the traction, stopping pattern as many areas will have multiple planning headways for the same section.

== Doublepost prevention - post automatically merged: 28 Dec 2025 ==


You could run on Sunday mornings now if someone wanted to staff the boxes.

Agree with other suggestions as well such as the Marches and Castle Cary.

Still 6 signal boxes plus a gate box at Egginton on the North Staffs, isn't there. Was originally in the plan for Derby resignalling if I recall. Plus work on Meir tunnel....

 

[The Planner]

Still 6 signal boxes plus a gate box at Egginton on the North Staffs, isn't there. Was originally in the plan for Derby resignalling if I recall. Plus work on Meir tunnel....

Still just a numbers game. If there was a real desire to run an earlier services on a Sunday someone would subsidise it. Whats the longest section? Uttoxeter box to Caverswall? Thats 12 miles/14 minutes, easily doing 3tph with that.

 

[Trainman40083]

Still just a numbers game. If there was a real desire to run an earlier services on a Sunday someone would subsidise it. Whats the longest section? Uttoxeter box to Caverswall? Thats 12 miles/14 minutes, easily doing 3tph with that.

Seem to recall there used to be some form of box at Upper Leigh too, on that section. Been a few times, when I have been on a Crewe to Derby train, following behind a steel or coal train.

 

[pokemonsuper9]

Assuming it could fix the freight train messing up the stopping pattern, or enable introduction of 3tph, the Atherton line.

 

[AlastairFraser]

Resignal Wigan NW through to Euxton Jcn, preferably with provision for extension of the 4 track section and lower headways so at least a 2tph service can be provided for the new Golborne station (perhaps the Barrow/Windermere to Man Airport service could be routed back via Wigan and the Chat Moss as one of them), and added reliability for intercity/regional services on this section of the WCML.

I also understand that a Coppull station is desired at some point, but I think the 4 track section extension would have to be completed before any reopening.

 

[The Planner]

Resignal Wigan NW through to Euxton Jcn, preferably with provision for extension of the 4 track section and lower headways so at least a 2tph service can be provided for the new Golborne station (perhaps the Barrow/Windermere to Man Airport service could be routed back via Wigan and the Chat Moss as one of them), and added reliability for intercity/regional services on this section of the WCML.

I also understand that a Coppull station is desired at some point, but I think the 4 track section extension would have to be completed before any reopening.

You would go all the way to Preston, Euxton to Preston would benefit more than the section south of there.

 

[AlastairFraser]

You would go all the way to Preston, Euxton to Preston would benefit more than the section south of there.

Fair enough, I wonder how much it would cost.

 

[The Planner]

Fair enough, I wonder how much it would cost.

Depends on how many panels Preston has and how many it triggers a resignalling on. Preston covers a significant area. Easily 8 figures.

 

[AlastairFraser]

Depends on how many panels Preston has and how many it triggers a resignalling on. Preston covers a significant area. Easily 8 figures.

Perhaps something to be considered as part of a wider WCML upgrade post HS2

 

[Harpo]

Shorter signal sections would reduce the linespeed from 125mph.

Only if it’s still lights-on-sticks.