• intersection is the bottleneck of urban traffic
  • intersection is very different from the highway, which means that the highway model may not be applicable


role of traffic light

  • assign access to different lanes

We can just consider one direction first. The other direction can be attained by symmetry.

Key factors of congestion in intersections

  • When the traffic light turns from red to green, all waiting cars starts from speed 0.
  • The destination of each car is different. The left-turn takes more time, since it may collide with the cars from the opposite direction.

One Intersection

  • Car follower model may be applied to model the traffic when the traffic light turns green.
  • rate_all = rate_right + rate_straight + rate_left
  • What is the critical input arrival rate?

  • Traffic lights separate the left-turn traffic from others. Better efficiency?

From One Intersection to Urban Road Topology

  • Urban road topology can be constructed by connecting several intersections.
  • The simplest case is grid road topolgoy (Manhattan model), where the distance between intersections should be specified.
  • Will there be any cascade effect of delay in the network?


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