Congestion Management

Regardless of whether congestion is being caused by an accident or normal rush hour traffic, the changeable message signs are capable of automatically displaying information related to the level of congestion on the freeway. In the Toronto COMPASS System, the messages describe the average traffic conditions on the express and collector lanes for a pre-defined upcoming section of the freeway. The average traffic condition is defined in terms of "MOVING WELL" (75 km/h and above), "MOVING SLOWLY" (40 to 75 km/h), and "VERY SLOW" (less than 40 km/h). Motorists may use this information to decide whether to continue travelling on their original route or take an alternate route by transferring onto the express or collector lanes. In the Missisauga and Burlington COMPASS Systems on the Queen Elizabeth Way, the congestion messages describe the average traffic conditions and the congestion area boundaries with respect to the CMS location. If the CMS is upstream of the congestion area, the message will warn motorists where the arrival end of the queue starts. If the CMS is already within the congestion area, the message will let motorists know the downstream end of the congested queue.

The congestion management program is a fully automated system using data from the vehicle detector stations installed in the COMPASS System to select and display congestion management messages on the changeable message signs. As often as every 20 seconds, the COMPASS computer calculates the travel time for vehicles over pre-defined sections of the freeway and updates the messages on the signs based on the average speeds and travel times calculated. Used properly, this traffic information can help balance the traffic flow, maximize roadway capacity usage, reduce motorist travel times, and improve safety on the freeway.