tj.stevenson
Member
- Joined
- 16 Aug 2015
- Messages
- 7
Apologies for the poor picture, but I wonder if someone could satisfy my curiosity regarding these very common trackside installations.
As they occur in large regularly spaced groups and seem to have some optical components, I have wondered for a long time what it is they do.
As they occur in large regularly spaced groups and seem to have some optical components, I have wondered for a long time what it is they do.