Platform Signals at Birmingham New Street

[meepmeep]

I have been watching this video of trains in and out of New Street

I'm curious as to the patterning on the red platform signals. Does anyone know why they are not a solid red and also seem very large?

Forgive me if it's a dumb question!

Jeremy

 

[John Webb]

They are LED signals and the patterning is because the different coloured LEDs for the different aspects are intermixed with each other. As far as I can see they are the same size as other colour light signals - about 9inches/230mm in diameter.

 

[meepmeep]

Thank you John! I have learned something today.

 

[Signal Head]

These are 'VMS' LED signals. They do have a larger apparent aspect diameter than an old filament type head with glass lenses. I think the old lenses are about 8" diameter. Part of the apparent increase may well be because the light is evenly spread over the entire aspect as it's provided by lots of small LEDs rather than a single, central source like a lamp. With the doublet lens arrangement there tended to be some 'fall-off' towards the circumference, more apparent in daylight.