Martin Brown wrote:

If you think we have a problem there are countries where traffic light
discipline is so bad that without policemen on every junction at rush
hour it all grinds to a complete standstill - think herringbone
pattern of cars in every junction all moving and hooting at random.

I've been at junctions where it ends up a free-for-all. The light goes
green for one road but access is obstructed, so they go on red. And
then it goes on from there - just go when you can. Many would say that
if the lights don't do their job, that's probably the best option.

Most gridlock (or starvation to be more technical) occurs where there
are two signals in close succession, such that the space between the
signals is filled quickly by one side and then the other side will have
nowhere to go. Actually this is commonly the situation at Henlys Corner
for the A406 Westbound. In the last couple of weeks they have been
resurfacing and there is currently no box junction and the approach has
become a lot emptier as a result.