The second type of adaptive traffic control systems often model traffic control as
a multi-stage problem or a MDP and solve it by dynamic programming or branch and
bound. Fuzzy logic, rule-based methods, and knowledge-based methods have also been
used in the second type of adaptive traffic control systems. For the second type of
adaptive traffic signal control systems, there are no fixed cycle length, phase sequence
and duration, and offset. All these parameters are determined in real time based on
existing and projected traffic flow conditions. The second type of adaptive traffic control
systems may not have the restrictions of cycle length, fixed phase sequence, phase
duration, and offset, and has attracted considerable attention in recent years. However,
this type of methods still has the following problems