Semaphores - paraffin/electrical lamps

[Phil25]

Hello. I was curious when exactly did electrical lamps on semaphores become common on british railways. After asking this question to an AI I didn't really get a response, I've only been told that it was 'around early to mid 20th century' and that 'old semaphores usually kept their oil lamps'. This answer doesn't quite satisfy me. In fact from my personal observations many mid-20th century stations still had oil lamps (based on the fact that many of the signal boxes had the lamp in/out indicators). Also the AI told me that some newer electric lamps used a lower voltage (?) or something like that in order to achieve the old green aspect (this happened because of blue lenses & the burning paraffin's color). But I haven't confirmed this yet and AI sometimes makes things up. Perhaps you could share your observations, I'm sure there will be even some stations that haven't changed to electrical lamps for a long time.

Some photos

Famous Exeter West Signal Box

Normal picture of an upper quadrant semaphore

Signal gantry, most of the signals are of old GWR design

 

[Gloster]

A few random comments. A major problem with using electric lamps in semaphores is that you either have to provide feeds to the signal at the appropriate voltage or have batteries, which need to be checked and either changed or recharged on site. The eight-day oil lamp does not have this problem: all you need is a Lampman, who can cover a lot of lamps in a day. You also have the fail safe principle: electric lamps may have to be treated as Out after a certain period of a power cut, while paraffin lamps are unaffected (*). Additionally, some signal boxes remained without electric mains well into the 1980s.

Quite simply I think that the rate of conversion was slow, particularly in rural areas, as the savings were modest compared to the costs. When short of cash, the railway had much more effective ways of saving cash than eliminating a simple and robust practice. I was a Lampman and a Si[gnalman in boxes with paraffin-lit signals.

* - Paraffin lamps are pretty reliable, but they do go out. I have memories of climbing a high Home Signal in the rain because the lamp had gone out in a gale sweeping across the Somerset Levels, but such events were rare if the Lampman knew his job.

 

[Rescars]

Presumably semaphores would need at least some simple wiring to operate their lamp in/out indicators. Were these fitted to all signals as a matter of course, or could direct observation and/or visual tell-tales be relied on for lamps in direct line-of-sight from the box?

 

[frankmoh]

The 1975 Nuneaton crash was caused by dodgy gas lighting, so I assume BR has thought about switching over to electric some time after that.

 

[Gloster]

Presumably semaphores would need at least some simple wiring to operate their lamp in/out indicators. Were these fitted to all signals as a matter of course, or could direct observation and/or visual tell-tales be relied on for lamps in direct line-of-sight from the box?

Normally signals that could be seen clearly from the box did not have a Light In/Light Out indicator as the signalman could check them; if he could only see the rear, there was a small eyelet in the lamp case that was visible when the signal was at Danger. It was only signals out of the view of the signalman that had the In/Out indicator fitted in the lamp case and wired to an indicator in the box..

 

[John Webb]

Those signals out of sight of the box were fitted with a bimetal strip which, if the lamp went out, broke a circuit. This could either be relayed independently to the supervising box, but sometimes formed part of the signal arm repeater circuit. These circuits comprised a switch with two contacts linked to the signal arm and a pair of local batteries. With the arm at either danger or proceed, a voltage was sent to the box which operated an indicator in the box to show what the arm was indicating. If the arm wasn't at the correct position (within certain limits) no voltage was sent to the box and the box indicator would show 'Wrong'. The lamp warning could be added to this circuit to break it if the lamp went out; the indicators in the box were than usually be marked 'Lamp out' instead of 'Wrong'. (Apologies I've no close-ups of such indicators at St Albans South!)

 

[matchmaker]

Don't believe AI - according to it there are still oil lit semaphore signals on NR in Scotland. As far as I know, all remaining NR semaphore signals in Scotland have been electrically lit for at least 10 years!

 

[John Webb]

.....Also the AI told me that some newer electric lamps used a lower voltage (?) or something like that in order to achieve the old green aspect (this happened because of blue lenses & the burning paraffin's color). But I haven't confirmed this yet...

The AI got that correct. Running the filament lamp at, typically, 10volts for a 12volt bulb, gives a yellower colour more like that of the paraffin lamp's flame colour and so gives the required green light through the blue filter on the signal arm. It also has the advantage that the electric lamp life is much extended by running at a lower voltage, so the bulbs need changing less frequently.

We have fitted a number of our semaphore signals displayed at the St Albans South box with 'warm white' LED lamps but have still had to add a yellow filter in front of the lamps to get the right 'green' appearance through the blue filter.

 

[Harpo]

Hereford still had a lampman around 1998. NR made him redundant and paid him off so that the maintainer could employ him to do the same job the following week.

 

[MarkyT]

I believe working at height H&S concerns finally killed off the oil lamp on a wide scale. Ground signals that don't involve climbing to access can still have them theoretically, but once the tall semaphores are tackled in an area, it makes sense to eliminate all the oil lamps. With primary cells for illumination in areas without mains supply, locked battery boxes can be mounted low down on the signal post so can be reached without climbing any ladders. Modern NR approved LED oil lamp replacement units have voltage free proving contacts that can operate indicator and alarm circuits. If a semaphore signal needed lamp repeat indications for an oil lamp, then the same feature is always replicated in its electrical replacement. Batteries for these installations are typically changed on a 3 month cycle, lasting significantly longer between attention than their oily forebears.

 

[Llanigraham]

Hereford still had a lampman around 1998. NR made him redundant and paid him off so that the maintainer could employ him to do the same job the following week.

Caersws and Llanidleos Rd level crossing, on the Cambrian, had parafin lamps right up to the time ERTMS took over on the line.
The Lamp Hut is still in-situ at Caersws station.

 

[satisnek]

The semaphore signals at Kidderminster were oil lit up until the 2000s and only had electric lighting for the last few years of their existence. They contrasted sharply with the SVR's signals which were electrically lit from installation.

As an aside, those who have visited the SVR will have probably noticed the 'fairy lights' strung down the platform at Kidderminster Town. These were originally erected for the Queen's Platinum Jubilee in 2022 but have since become the permanent illumination in place of the gas lamps (I think there's an issue with the piping). They're LED filament lamps with two filaments and have a yellow/orange glow which is emulative of an oil flame. Could these be specialist railway signalling lamps which would explain why I can't find them on Amazon?

 

[Phil25]

This could either be relayed independently to the supervising box, but sometimes formed part of the signal arm repeater circuit.

Your response reminded me of a certain video and I managed to find it, it's a 1950s Absolute Block guide, you can see this kind of repeater (shown below). However I think these kind of repeaters were unusual, atleast for some companies.

if he could only see the rear, there was a small eyelet in the lamp case that was visible when the signal was at Danger

I looked up some semaphores and that's indeed correct, I'm assuming that they all had these small eyelets (some pictures I found shown below, they all have this eyelet)

(appears to be a Midland lower quadrant signal)

(lower quadrant signal, you can see what appears to be an eyelet)

(upper quadrant, probably the best example I've found)

 

[John Webb]

I looked up some semaphores and that's indeed correct, I'm assuming that they all had these small eyelets (some pictures I found shown below, they all have this eyelet)

The 'eyelet' is known as the 'Backlight'.

(appears to be a Midland lower quadrant signal)

It is indeed a Midland Railway signal, I suspect possibly not far from St Pancras.
Of note is the 'blinder' - a form of 'shutter' which moves in unison with the arm, and which shuts off the backlight when the arm is in the clear position. So besides the backlight allowing the signalman to see the lamp is burning, it also helps him to check that the arm is moving correctly at night.

 

[Gloster]

The 1975 Nuneaton crash was caused by dodgy gas lighting, so I assume BR has thought about switching over to electric some time after that.

But that was on a Temporary Speed Restriction board and, by their nature, changing them over to electric supply was a lot more difficult. They are also not part of the signalling system.

 

[matchmaker]

The semaphore signals at Kidderminster were oil lit up until the 2000s and only had electric lighting for the last few years of their existence. They contrasted sharply with the SVR's signals which were electrically lit from installation.

As an aside, those who have visited the SVR will have probably noticed the 'fairy lights' strung down the platform at Kidderminster Town. These were originally erected for the Queen's Platinum Jubilee in 2022 but have since become the permanent illumination in place of the gas lamps (I think there's an issue with the piping). They're LED filament lamps with two filaments and have a yellow/orange glow which is emulative of an oil flame. Could these be specialist railway signalling lamps which would explain why I can't find them on Amazon?

The signals on the SVR were definitely not electrically lit from installation. I remember having to fill, trim, light and install all the signal lamps at Bridgnorth one Saturday afternoon in the late 1970s as there was late running that evening. I even lit the lamp at the (fixed) distant, which gave the loco crew a hell of a shock as they'd never seen it lit before!

 

[satisnek]

The signals on the SVR were definitely not electrically lit from installation. I remember having to fill, trim, light and install all the signal lamps at Bridgnorth one Saturday afternoon in the late 1970s as there was late running that evening. I even lit the lamp at the (fixed) distant, which gave the loco crew a hell of a shock as they'd never seen it lit before!

Sorry, I wasn't being clear. Those at Kidderminster were.

 

[matchmaker]

Sorry, I wasn't being clear. Those at Kidderminster were.

I understand now.

 

[MarkyT]

Your response reminded me of a certain video and I managed to find it, it's a 1950s Absolute Block guide, you can see this kind of repeater (shown below). However I think these kind of repeaters were unusual, atleast for some companies.

View attachment 190300

I don't recall these on the WR or SR. WR boxes typically had a round 3 position on - wrong - off arm indicator for each signal, balanced to wrong, driven by a polar circuit powered from a local equipment cabinet near the signal, often using primary cells where there was no mains. Lamp repeats were usually summated in groups of signals, each indicated by a lamp indicator unit with a built-in alarm bell relay along with an acknowledgement switch and a test key.

Signal arm indicator above, later variant. Other round variants depicted a mini signal arm instead of the arrow, and there were earlier wooden boxed designs similar to lamp indicator/alarm units, as seen below.

 

[Welly]

Lincoln station did have oil lit semaphores in the station area into the 21st century but the ones furthest out were electrically lit. All the semaphores were removed in 2008.

 

[D1511]

I can remember the paraffin smell from the semaphores controlled from Kingsknowe box when I used to spot there in the late 70s. They were removed in about 1980 along with the hand wound level crossing.
If I encountered that smell again now, it would be a "Proust's Madeleines" moment!

 

[Gloster]

I can remember the paraffin smell from the semaphores controlled from Kingsknowe box when I used to spot there in the late 70s. They were removed in about 1980 along with the hand wound level crossing.
If I encountered that smell again now, it would be a "Proust's Madeleine's" moment!

Just don’t dip your madeleine in paraffin.

 

[John Webb]

I can remember the paraffin smell from the semaphores controlled from Kingsknowe box when I used to spot there in the late 70s. They were removed in about 1980 along with the hand wound level crossing.
If I encountered that smell again now, it would be a "Proust's Madeleines" moment!

Shame you're not near us at St Albans - we have a number of paraffin lamps we put on display on our open afternoons at the St Albans South box; people do often comment on the smell!
In fact, we never started off in 2008 with the intention of having such lamps on display! We'd built a replica 'Lamp Hut' for storage and then people started giving us lamps to put in it, so we got them into working order and a quarter of the lamp hut is now used for lamps.

 

[Chrius56000]

. . .Did Morecambe Promenade Station have Paraffin Lit Semaphore Signals up to its closure in 1994?

. . .I remember my Dad's Late Neighbour, Mr. Middleton, who was the Railman there prior to closure, said that the few signals at what was left of Torrisholme Junction that remained on the Heysham Port branch didn't have any lamps as there were no trains timetabled to use the branch in darkness, was he correct?