Abstract:To find an effective method to control an oversaturated network,it is essential for the traffic control system to make a quick response to the oversaturated circumstance.Accordingly,the traffic signal control subarea related to the oversaturated link should be delimited at the very beginning.The oversaturated link was identified at first,and then the connection model was presented and verified on the basis of quantizing the connection index between intersections.A dynamic method was proposed to delimit the coordinate control subarea under oversaturated condition by defining the congested area,interim area,normal-state area and dissipated area.The threshold values of connection index for subarea delimitation were calibrated and the detailed steps of delimitation were also explained via a case study.The research of delimiting signal coordinate subarea under oversaturated state lays the foundation for the research of traffic control strategies for an oversaturated urban traffic signalized network.