"Basil Jet" wrote in message
...

Late at night, the traffic lights on Finchley Road at the junction of West
Heath Avenue often go red for a couple of seconds before reverting to
green. This is far too short for another traffic or pedestrian phase to
have occurred in between. It seems that sensors facing into the side roads
detect that there is no traffic there and that this causes the green phase
for the side roads to be skipped, but unfortunately the other lights have
flipped to red before this decision is made. Surely this must be a mistake
rather than design.

It is quite common for lights to run though a short cycle when they have not
been triggered for some time. I presume the controller is running some sort
of error check sequence.

Colin Bignell