Behaviour of traffic lights on an intersection

[Phystam]

In today's society, motorisation has led to an enormous number of private vehicles. This can lead to traffic concentrations in several places and deadlocks at junctions. The installation of traffic lights helps to avoid deadlocks to a certain extent, but there is still a risk of deadlocks when the traffic is very heavy.
Observations suggest that deadlocks are caused by the fact that there are only two phases This means that after the end of the east-west traffic, the north-south traffic starts immediately, even though there are still private cars in the intersection, causing a deadlock.
Therefore, a "yellow light" is considered necessary to avoid deadlocks. The yellow light blocks traffic entering the intersection from both the east-west and north-south directions, but does not block traffic exiting the intersection. The yellow light phase lasts until the car has completely exited the intersection. If the yellow light condition persists for any length of time, the vehicles in the intersection will be removed and the next phase will take place.

↓ private cars block each other...