Methodology for Variable Speed Limit Activation in Active Traffic Management

Active Traffic Management (ATM) is a tool that can stabilize traffic flow and improve safety by dynamically managing and controlling traffic based on the prevailing traffic conditions. This paper analyzes the traffic flow characteristics of G6 freeway in Beijing of China based on survey data. The relationships among traffic parameters such as standard deviation of speeds (SDS), average speed and occupancy are established in order to calibrate the critical thresholds for the activation of a VSL system in ATM. Furthermore, the control logic of a VSL system is proposed based on the relationships between SDS and other parameters.