Bracket signals. Is there a standard clearance above rail

[dasatcopthorne]

Guys.

 

Does anyone know if there is a standard 'clearance from rail to underside of a bracket signal on Non-Overhead lines please.

 

Dave.

[Compound2632]

The standard structure gauge, I would suppose?

[Kris]

There would be a minimum clearance but I suspect that the height above this would be subject to sighting lines. 

[Miss Prism]

Don't forget to allow for smoke deflectors on the undersides of gantry signals, where these were fitted (some companies seem to like them, others did not).

 

[TheSignalEngineer]

Non-electrified lines loading gauge plus 12 inches was specified for steam traction at least as far back as the 1928 Requirements.  If possible electrification was to be considered it was 15 feet above rail level.

[TheSignalEngineer]

It also depends where they were located if they were outside the minimum required clearance from the side of the track they could be any height. We had one at Langley Green where you could virtually step onto the landing from ground level. 

Different rules applied if situated on the passenger areas of a platform. In this situation the required clearance was the whole structure to be at least 6 feet back from the platform edge and providing 8 feet 6 inches clear headroom above the platform surface.

Edited March 14 by TheSignalEngineer
Headroom corrected,

[Wickham Green too]

2 hours ago, TheSignalEngineer said:

... If possible electrification was to be considered it was 15 feet above rail level.

Would that be above running rail or above third rail ?  🙄

[Compound2632]

3 hours ago, TheSignalEngineer said:

Non-electrified lines loading gauge plus 12 inches was specified for steam traction at least as far back as the 1928 Requirements. 

 

Is that a greater clearance than the structure gauge?

[TheSignalEngineer]

29 minutes ago, Wickham Green too said:

Would that be above running rail or above third rail ?  🙄

Running rail. Third rail followed same rules as steam.

[Michael Hodgson]

3 hours ago, TheSignalEngineer said:

Different rules applied if situated on the passenger areas of a platform. In this situation the required clearance was the whole structure to be at least 6 feet back from the platform edge and providing 8 feet 6 inches clear headroom above the platform surface.

Would that headroom be measured to the bottom of the upper quadrant arm in the on position lower quadrant arm when off, and similar allowance for movement of the spectacle plate?

[TheSignalEngineer]

1 hour ago, Michael Hodgson said:

Would that headroom be measured to the bottom of the upper quadrant arm in the on position lower quadrant arm when off, and similar allowance for movement of the spectacle plate?

It is the clearance to any part if the structure, be it post, flitches, arms. If a lower quadrant arm is hung down from the roof or a gallows bracket it would be to the tip ofthe arm in the OFF position

[TheSignalEngineer]

I've just corrected the platform headroom to 8 feet as in the Requirements in 1928 and 1950. My memory let me down but it is about 30 years since I personally signed off the paperwork for one.

We did tend to design to have the bottom of the structure of a colour light at a bare minimum of 11 feet above rail rather than measuring from the platform. You would always get a clever b******** who would decide that rebuilding thesubstandard platform would after all be in the project the week after the signal had been installed.

One Inspecting Officer seemed very keen on what he called the Umberella Effect. That was a SPAD caused by a  driver not seeing a red aspect as a city gent was holding his open brolly in line of sight. 

 

[TheSignalEngineer]

17 hours ago, Compound2632 said:

 

Is that a greater clearance than the structure gauge?

The Requirements were a minefield of Must Do, Desirable, contradiction and getout clauses. The 'Desirable Standard'  structure gauge for steam and 3rd rail shown on the drawing  in the Requirements was 15 feet above the running rail.

Company loading gauges at the time of the 1928 Requirements varied between 13 feet and 13 feet 9 inches.

The standard clearance above loading gauge was shown in the text as 12 inches. In certain circunstances this could be reduced as low as 6 inches with special permission from the  Inspectorate.

Edited March 15 by TheSignalEngineer

[TheSignalEngineer]

A couple of examples from my past.

 

First at Langley Green Middle. It's low for sighting under the footbridge. The R/H doll used to carry the distant arm for Langley Green East. 

 

Off topic note:- Tin shed on left is Cox & Danks who cut up a few locos in the 1960s including some Kings.

 

Next a standard GWR bracket for the Up Through line at Leamington with Gallows Bracket extemside to the left foe the Up Platform. It hangs down for sighting under the canopy.

 

This was its replacement. IIRC the red aspects were 16'6" Above Rail Level

[The Stationmaster]

On 14/03/2024 at 23:37, TheSignalEngineer said:

A couple of examples from my past.

 

First at Langley Green Middle. It's low for sighting under the footbridge. The R/H doll used to carry the distant arm for Langley Green East. 

 

Off topic note:- Tin shed on left is Cox & Danks who cut up a few locos in the 1960s including some Kings.

 

Next a standard GWR bracket for the Up Through line at Leamington with Gallows Bracket extemside to the left foe the Up Platform. It hangs down for sighting under the canopy.

 

This was its replacement. IIRC the red aspects were 16'6" Above Rail Level

The WR standard height above rail level for the red aspect of colour light signal heads mounted on either bracket or gantry structures was 17ft 6".  

 

The Leamington bracket picture above was of course erected by the LMR and appears to be the later BR standard style of bracket structure for such situations - the design seems to have been deveopled from a tructure designed by the Southern Region judging by where the earliest examples seem to have appeared.

 

The middle photo shows Leamington South's Up Main Home (right hand doll) and Up Platform Line Home Signals and was altered during the LMR era .   The signals in that spot had a fascinating, and in some respects unusual, history.  The earlier bracket signal on that site had every appearance - from the spacing of the dolls - to be a splitting (junction) signal but it wasn't - the higher doll, on the right - was the Up Main Line Inner Home while the doll on the left, with arms at a lower elevation, was the Up Platform Line Home Signal; the signal also had centre pivot arms instead of normall full length arms..  Both dolls carried a lower arm distant signal for Leamington South Jcn.

 

The replacement tubular steel structure had both dolls above the platform of the bracket structure and was photographed (see Warwickshire railways site) in that form but with the arms altered to Upper Quadrant by the LMR.   I don't know when the original Up Main Home Signal - bracketed from the platform canopy was removed thereby causing the arm applying to become the Up Main the Home Signal.   SE's photo shows the structure in what was, I believe,  its final state with the arm applying to the Up Platform Line altered to provide better sighting from trains standing under the canopy and for platform staff.

[TheSignalEngineer]

On 24/03/2024 at 16:41, The Stationmaster said:

The Leamington bracket picture above was of course erected by the LMR and appears to be the later BR standard style of bracket structure for such situations - the design seems to have been deveopled from a tructure designed by the Southern Region judging by where the earliest examples seem to have appeared.

 

The middle photo shows Leamington South's Up Main Home (right hand doll) and Up Platform Line Home Signals and was altered during the LMR era .   The signals in that spot had a fascinating, and in some respects unusual, history.  The earlier bracket signal on that site had every appearance - from the spacing of the dolls - to be a splitting (junction) signal but it wasn't - the higher doll, on the right - was the Up Main Line Inner Home while the doll on the left, with arms at a lower elevation, was the Up Platform Line Home Signal; the signal also had centre pivot arms instead of normall full length arms..  Both dolls carried a lower arm distant signal for Leamington South Jcn.

 

The replacement tubular steel structure had both dolls above the platform of the bracket structure and was photographed (see Warwickshire railways site) in that form but with the arms altered to Upper Quadrant by the LMR.   I don't know when the original Up Main Home Signal - bracketed from the platform canopy was removed thereby causing the arm applying to become the Up Main the Home Signal.   SE's photo shows the structure in what was, I believe,  its final state with the arm applying to the Up Platform Line altered to provide better sighting from trains standing under the canopy and for platform staff.

The semaphore was altered when the layout changes at the North box were made, I think it would be 1966. It was like that in March 1967. I haven't got an exact date for my photo but the one before was Western Invader and the one after Western Fusilier. My guess based on that would be late 1976.

Leamington platform end bracket and the Up Starter were replaced by colour lights either late 1977 or early 1978 as spot renewals. At the time I was doing a resignal by stealth of as many bits of the Banbury line as possible under the cover of track remodelling. box rationalisation, DM's minor works and S&T minor renewals. In nine years we managed to renew all of the main line running signals and provide track circuits for most sections on nine route miles, reducing ten boxes to five, increasing MGR train loads and improving headway times in the process.