BR Mark 3 Coach?

Question

What are those orange square lights right next to the door outside on the BR Mark 3 Coaches?

thanks

Answer 1

If these are lit the brake interlock will not alow the train to move in a service condition.

With a locomotive coupled the train can be moved when they are lit if the dummy loco(TDM)is not attatched, though this is in a maintenance/shunting condition.

Answer 2

The orange door indication lights are part of a central door locking system intoduced in the late 80's early 90's after a series of accidents where passengers had fallen from trains.

Once all the trains doors are shut prior to departure, additional electric shunt locks activate to lock the door to prevent it being opened without authority from the guard/train manager.

The light indicates whether the lock has deployed or not.

Once all door indicator lights are out..then the train may depart.

Answer 3

Andy M is spot on. You will also see similar things on other carriages too.

Answer 4

They're part of the central locking system. They're illuminated when the central locking is released and provide an indication that the doors aren't locked.