Samenvatting
This revision of BS 505: 1939 has been prepared with the primary objective of introducing the higher optical requirements which research by the Road Research Laboratory has shown to be essential for modern traffic systems control. The opportunity has also been taken to delete reference to hand-operated fixed-time signals, as these are no longer in use. Detailed operating requirements for controllers have also been removed at the request of the Department of the Environment, since this subject is covered in greater detail than can be included in a British Standard in their own specification.