Why have semaphore signals & boxes mostly been replaced

[Falcon1200]

could semaphores be controlled from a signalling centre; by means of devices in the structure programmed and activated remotely to raise or lower the signal arm?

Those semaphores would still need lights, to be visible after dark, so why bother with the arms at all - What exactly would be the advantage of semaphore arms over powerful colour lights?

 

[zwk500]

I understand the arguments about boxes being labour intensive and not cost effective, but just focusing on the suitability of semaphore signals for fast, busy lines. In theory would it be possible to have 4-aspect semaphores to allow 125mph running at 3-minute headways, and could semaphores be controlled from a signalling centre; by means of devices in the structure programmed and activated remotely to raise or lower the signal arm?

Just what advantage would this offer to the modern railway and it's passengers and end customers?

 

[Philip]

Again I understand the need for powerful lights to be fitted, but I'm sure these could be fitted into the signal arm. I do think keeping an element of heritage even on the mainline should be factored in; it's not just enthusiasts who appreciate this. I'm not suggesting a full-scale replacement of traffic light signals with semaphores, but it would be good if we could see them reinstated in places, albeit with suitably strong lights and a means to operated from the nearest signalling centre, if there is no box nearby.

 

[SynthD]

4-aspect semaphores

What are the four aspects that are as distinct as four different coloured lights? There may be a risk in trying to indicate one thing by pointing down, and another by pointing up. It just looks like the red thing is in its vertical position.

 

[The exile]

What are the four aspects that are as distinct as four different coloured lights? There may be a risk in trying to indicate one thing by pointing down, and another by pointing up. It just looks like the red thing is in its vertical position.

That’s not a problem - each post has a distant arm as well - which has 3 positions: horizontal, vertical and what we would currently recognise as “off”. However - what’s the point? It’s probably a bit cheaper than full ETCS - but not much!!

 

[HSTEd]

That’s not a problem - each post has a distant arm as well - which has 3 positions: horizontal, vertical and what we would currently recognise as “off”. However - what’s the point? It’s probably a bit cheaper than full ETCS - but not much!!

I doubt it is cheaper than ETCS.
The cost of staffing all these signal boxes will swamp anything, and even if they are remotely controlled you still will need all this extra trackside equipment.

 

[Llanigraham]

I'm trying to work out how the relationship between an upper or lower quadrant signal and it's lever in the Box would work with a signal showing more than 2 aspects. There are enough problems now in hot weather getting them to work properly.

 

[Llanigraham]

That’s not a problem - each post has a distant arm as well - which has 3 positions: horizontal, vertical and what we would currently recognise as “off”. However - what’s the point? It’s probably a bit cheaper than full ETCS - but not much!!

How are you going to get that to work with a lever in a signal box?

 

[The exile]

I doubt it is cheaper than ETCS.
The cost of staffing all these signal boxes will swamp anything, and even if they are remotely controlled you still will need all this extra trackside equipment.

I was thinking of installation, rather than operation - it’s all a bit academic because it would be a completely daft idea anyway.

 

[Meole]

Automatic level crossings replaced 1000s of boxes, more efficient and safer.

 

[Bald Rick]

Where‘s @MarkyT when you need him?

Fairly sure you cant have sempahores above 100mph. Also I don’t know anywhere that does sempahores at 3 minute headways, but I expect someone will be along shortly to tell me I’m wrong.

 

[Falcon1200]

Also I don’t know anywhere that does sempahores at 3 minute headways

A signaller working a manual box with that level of traffic would need (or would soon have) arms like Popeye!

 

[HSTEd]

Where‘s @MarkyT when you need him?

Fairly sure you cant have sempahores above 100mph.

Well conceptually you would just need boxes that did nothing but set distants for the "main" box, using some ludicrous rodding-based interlocks between boxes.

And no, I don't think is really a practical solution either.

 

[Mgameing123]

The railways managed with semaphores and boxes for 100-150 years, why are they unsuitable now? If a semaphore has a preceding caution signal why is it unsuitable for fast or busy stretches of line?

Because with modern signaling systems like ETCS we can trains more closer to each other than what we can achieve with semaphore signals. Semaphore signals work best on rural branch lines with very little traffic. NOT mainlines like the West Coast Mainline.

 

[Dr Hoo]

Fairly sure you cant have sempahores above 100mph. Also I don’t know anywhere that does sempahores at 3 minute headways, but I expect someone will be along shortly to tell me I’m wrong.

I have worked Birkenhead Park in the evening peak in the 1970s with semaphores on one occasion with an experience relief man to keep me straight. (We didn't use 'Call Attention' on the block bells but at least we didn't degenerate to the 'Improved Merseyside Two Position Open Block' method.)

A signaller working a manual box with that level of traffic would need (or would soon have) arms like Popeye!

Not semaphores and it was TCB, but Gillingham box had kept the lever frame into the 1980s. My duties allowed me to often 'drop in' and work it for an hour in the morning peak to keep my hand in. Sixteen Up trains, plus Down ones, including terminators, the connections out of the Depot and a very busy level crossing, worked from a separate plinth. Magazine train describers and an open circuit 'squawk box' intercom down to the station platform and supervisor to say which train was next at each platform so that they could put the wooden finger boards up. The regular signaller just made the tea and gave a running commentary on my efforts. Not time to sit down and certainly kept me fit.

 

[High Dyke]

In a number of re-signalling schemes (Nottingham East project springs to mind), four signal boxes closed and control moved to East Midlands Control Centre at Derby. Whilst some level crossings were upgraded and semaphore signals replaced, the scheme now has less colour lights on the line from Netherfield Jn - Allington West Jn than it did with semaphore signals. The line from Netherfield Jn - Newark Castle saw slightly different changes. How can that be an improvement?

Equally, there have been proposals over the years to reduce signal boxes on many rural routes, where semaphore signals may prevail. However, these haven't really come to fruition. The Network Rail '30-year' masterplan was out of date before it got started properly. And timescales for closures are regularly slipping backwards.

 

[HSTEd]

In a number of re-signalling schemes (Nottingham East project springs to mind), four signal boxes closed and control moved to East Midlands Control Centre at Derby. Whilst some level crossings were upgraded and semaphore signals replaced, the scheme now has less colour lights on the line from Netherfield Jn - Allington West Jn than it did with semaphore signals. The line from Netherfield Jn - Newark Castle saw slightly different changes. How can that be an improvement?

Because it likely requires substantially less effort, and personnel, to keep the modern scheme operational.
The objective is not necessarily capacity maximisation in a vacuum, the objective is an economic railway.

Equally, there have been proposals over the years to reduce signal boxes on many rural routes, where semaphore signals may prevail. However, these haven't really come to fruition. The Network Rail '30-year' masterplan was out of date before it got started properly. And timescales for closures are regularly slipping backwards.

Well that says more about the dysfunction of the railway resignalling programme than anything else.

 

[High Dyke]

Well that says more about the dysfunction of the railway resignalling programme than anything else.

In some respects that's a good thing. It keeps me in a job.

I'm getting a bit long in the tooth, at my age, to apply for other roles.

 

[Llanigraham]

A signaller working a manual box with that level of traffic would need (or would soon have) arms like Popeye!

Not neccessarily. If the semaphores have been converted to colour light, like many Distant signals, the levers are cut short and don't need much of a pull. I could do the ones in my Box with one hand.

 

[30907]

Also I don’t know anywhere that does sempahores at 3 minute headways, but I expect someone will be along shortly to tell me I’m wrong.

Since you ask - Hampton Court Jn to Woking Jn possibly? Or the Jazz out of Liverpool St?

 

[Bald Rick]

Whilst some level crossings were upgraded and semaphore signals replaced, the scheme now has less colour lights on the line from Netherfield Jn - Allington West Jn than it did with semaphore signals. The line from Netherfield Jn - Newark Castle saw slightly different changes. How can that be an improvement?

Safer, and improved efficiency.

Since you ask - Hampton Court Jn to Woking Jn possibly? Or the Jazz out of Liverpool St?

I meant now, not the best part of a century ago!

 

[MarkyT]

Where‘s @MarkyT when you need him?

Fairly sure you cant have sempahores above 100mph. Also I don’t know anywhere that does sempahores at 3 minute headways, but I expect someone will be along shortly to tell me I’m wrong.

I'm not sure where that's stated explicitly, but I can't believe a semaphore would meet readability requirements nor be suitable at such high speed in the dark without an extraordinarily bright coloured lamp illuminated alongside, so the arm might just as well be dispensed with. Early 100+mph lines e.g. ECML, GWML were already colour lights throughout and MML was resignalled shortly before higher speeds were introduced. There may also have been a desire for AWS at all signals when raising speeds which really needs colour lights for full effectiveness. Semaphore stop signals are not typically equipped with a magnet, unless there's a distant on the same post, in which case there must be braking distance to the next stop signal ahead, not usually the case between the typical sequence of Home, Starter, Section Signal in a traditional semaphore layout. If a colour light replaces a semaphore signal in such a sequence, apart from the section signal, it must have a caution aspect and thus have braking distance to stop signals ahead, or an approach time delay can be added in the circuitry to automatically bring the train under control before the signal clears to yellow if the next is at danger - that's not favoured in new schemes as it arguably introduces preemption risk. In many small colour light conversion schemes retaining local control, signals were moved for braking reasons and the number of signals in a particular direction sequence was often reduced as part of that, fitting well with other simplifications such as removal of redundant yard and branch connections. Control could remain by the mechanical frame with levers acting as jumbo switches or a new small panel might replace it. Many remaining smaller boxes on secondary lines are like this. The ones that survive are often at remaining junction complexes or particular level crossings difficult to control other than by local supervision. Control areas were expanded to fill the gaps between these, with IB signals added to retain capacity under AB or conversion to full TCB. Smaller boxes have usually had equipment renewed and modernised repeatedly over the years with extra protections added to interlocking and block. Some are almost entirely state of the art modern with LED signals, axle counters, new panels and interlockings etc. Because their areas of control have typically grown over the years some remaining small boxes have come to oversee or control a large number of level crossings including public vehicular types, private crossings, foot and bridle ways, many of which have telephones. It is sometimes these crossings that make such an area difficult to transfer to a nearby large PSB or ROC. Although the limited number of extra points and signals might fit easily on an existing workstation, the crossing tasks could bust the workload for the position so an additional desk may be required, often staffed at a higher grade than the local signaller replaced.

In the early days, there were remarkable throughputs at many mechanical signalboxes in the London area on Great Eastern, South Eastern, etc. Staff must have been constantly operating levers back and forth at some times. Many were multiple-staffed on busy shifts and there were often 'booking boys' on duty to fill entries in the train register as the signallers couldn't let up lever pulling and bell tapping for long enough to write their own between trains. Unsurprisingly, the busiest areas were earliest to be converted to electrical or pneumatic signalling which could be operated from miniature lever frames, then switch panels, and that led to further centralisation opportunities as the concepts of route setting and remote control of unstaffed local interlockings over distance were developed.

Control centralisation has been a major theme in signalling since the earliest days with many technical developments allowing the range of control and supervision to be extended safely: track circuits, point machines, motor-worked semaphores, colour lights, CCTV, telemetry, etc.

What is modern and traditional anyway? Engineers can build almost anything you want. You could attach a motor-worked semaphore to an SSI or overlay ETCS of some form on a wholly mechanical layout. In the 90s, the original Jubilee Extension resignalling proposed a CBTC overlay on the Metropolitan surface section using the existing mechanical interlocking machines and miniature lever frames albeit controlling wholly colour light signals, apart from LUs electro-pneumatic semaphore shunting discs. That project foundered and the new trains used traditional signalling and trainstops for a few years until Seltrac could be substituted. At Medstead and Four Marks, the Mid Hants Railway has a traditional semaphore layout, apart from a new colour light Home tucked around the corner in one direction out of sight of the platforms). You won't find anyone pulling levers in the traditional signalbox today though as control has been transferred to a new cabin nearby with an IFS panel and relay interlocking. The layout has full track circuiting, point machines and electro-hydraulic actuation of the traditional semaphores temporarily while the old building and lever frame are being fully refurbished. The Ecclesbourne Railway is planning to incorporate SSI in a future signalling scheme, the first processor-based full interlocking in heritage I think. The pioneers of that tech are probably mostly retired now and the railway is close to the former home of BR Research. It is arguably heritage of its own right now, but I can see the grey boxes and 19" racks with flashing lights would be a somewhat niche interest!

 

[High Dyke]

Safer, and improved efficiency.

Not entirely. Signal sections are now longer, although the service frequency has not increased. On that basis replacing the semaphore signals has not necessarily improved efficiency.

 

[Bald Rick]

Not entirely. Signal sections are now longer, although the service frequency has not increased. On that basis replacing the semaphore signals has not necessarily improved efficiency.

Improved efficiency in that there is less to operate, maintain, repair and renew, and less to go wrong, all of which means lower costs, for no reduction in output. That is the very definition of improved efficiency.

 

[Harpo]

@MarkyT mentions ‘booking boys’. ‘Train Recorders’ were still employed in some GEML panels in the late 1970s, and maybe beyond, doing that same job of writing up the TRB.

 

[InkyScrolls]

Again I understand the need for powerful lights to be fitted, but I'm sure these could be fitted into the signal arm. I do think keeping an element of heritage even on the mainline should be factored in; it's not just enthusiasts who appreciate this. I'm not suggesting a full-scale replacement of traffic light signals with semaphores, but it would be good if we could see them reinstated in places, albeit with suitably strong lights and a means to operated from the nearest signalling centre, if there is no box nearby.

But why?

 

[D365]

It would be cheaper to put a semaphore on a tv controlled by in cab signalling. This tv could be repeated throughout the train for the passengers who want it. That's far more visible than putting them in actual signalling locations.

Such a facility does in fact exist in the form of ETCS ”Training Displays”.

But why?

Will somebody think of the enthusiasts!