Modern 1:76 Scale Colour Light Signals

[St. Simon]

The requirements generally are just to have the signal to the left or above the track it refers to, but it is also desirable to bring the red as close as possible to the drivers eye level. Hence signals suspended from gantries are usually in the 'valley' of the structure gauge where they can be as low as possible. With tracks at the standard 11ft 4 inch spacing that will put the signal 5ft 8 inches to the left of the track centreline. 900 mm would put the signal high up above the structure gauge line.

That said the Southern did seem fond of putting their signals on top of gantries rather than suspended and would thus have no particular constraint so may well have used 900 mm if the sighting was acceptable.

Regards

 

 

Hi,

 

Signals are positioned as to give the maximum readability to the driver, the actual reason for the signals being suspended from gantries is generally that they are found in OLE areas and the gantries need to be higher to clear the wires, thus the signals are suspended to ensure that they fall in the 3.3 to 5.1 metre limits, elsewhere they are mounted above the gantry, so that they can be worked on by staff more easily.

 

It is a standard that the centre of the most restrictive aspect, usually, but not always, a red, to be 3.1 metres from rail head, while for horizontal positioning, Railway Group Standard GE/RT8037 ' Signal Position and Visibility' Section C2.3.2 Paragraph 2 states:

 

 

Signals above the structure gauge (for example, gantry or cantilever mounted) shall usually be positioned with the centre-line of the most restrictive aspect approximately 900 mm to the left of the running edge of the left-hand rail. It is permissible for such signals to be positioned further to the right if by doing so:

 

a) the readability throughout the required reading distance is improved, or

b) the association of the signal with the correct line is improved. 

 

I was wrong in that it is the Left hand running rail to centre of aspect, not track centre to centre of aspect, I apolgise for giving misleading information.

 

Regards,

 

Simon Paley

[59004 ( was Shedcombe....)]

Hi Simon,

 

Thanks for these extra bits of info and further clarification. I have now 15 signals designed on my layout, of which 3 are on gantries above track at 900 mm off the centre of the track. Tomorrow I will correct these to 900 mm off the inside of the railhead of the lefthand running rail. Now off to bed, up again in 4 hours ....

 

Regards,

Michel