Optimizing Signal Timing at Multiple Intersections under Oversaturation Conditions

In transportation networks, traffic conditions are often in an oversaturated state. In this case, by coordinating the si gnal timing at multiple intersections to improve the significant road bottleneck capacity is necessary. Urban roads have entry capacity and exit capacity affected by the signal timing at intersection s and properties of left-turn lanes and straight lanes of roa ds. With the help of the discrete-time model, road entry capacity and exit capacity are formulated, and then the bottleneck road capacity under oversaturation conditions can be determined. Based on which, the objective function is to improve the significant bottleneck capacitie s and throughput of vehicles entering and leaving a special transportation n etwork by using effective green times at multiple intersect ions as the decision variables, through applying the Ant Colony Algorithm to find an optimal signal-timing plan. The results of numerical example indicate this approach to optimizing the signal timing of multiple intersections is feasible and effective.