Delimitation of Traffic Coordinated Control Sub-Area for the Road Network Containing Freeway

A practical approach is presented for determining boundary of urban traffic signal coordinated control sub-area when freeway exists. It is based on the analysis of quantitative measure of interconnection between intersection and freeway ramps. According to these quantitative indexes, those intersection(s) and ramp(s) that relate with each other closely should be delimited in the same sub-area and be coordinately controlled. The proposed approach lays a foundation for research on coordinated control of freeway ramps and adjacent intersections which is an essential element in improving efficiency and mitigating congestion of freeway network.