signal post id plates..

[nickt]

Hi all.
Does anyone know the reason for different colour signal id plates.
some were black background with white text and numbers and some white background with black text and numbers.
Thanks.

[Andrew]

Hi all.
Does anyone know the reason for different colour signal id plates.
some were black background with white text and numbers and some white background with black text and numbers.
Thanks.

I have asked a friend who is a signalling systems engineere, and he advises me as follows (cheers, Ron!):-

"Its a historical thing.

"Early" prefix plates are Black Text on White background

"Modern" prefix plates are White Text on Black background.

As for the reasoning, I don't have a clue (neither does my colleague!). At a guess, it was probably some pre-ergonomic ergonomist suggestion that White on Black stands out better than Black on White. However, they all tend to look the same when covered in snow! "

[nickt]

Hi Andrew,
Thanks for reply. And to your friend.
I had forgotten about my post, I was instructed in the end to use black back ground and white letter format in the end. Stands out well, but was still curious to know which colour scheme and when (roughly).