Development of freeway incident-based congestion measures

This research project presents the development of incident-based congestion measures to be used in testing the effectiveness of an ITS deployment program in reducing off-peak incident-based congestion. These measures are used to identify the location and quantify the duration of incident-based congestion on the freeway system as it exists today. These measures are also used to estimate aggregate delay and the characteristics of queues caused by incidents on various segments of the freeway network. To meet these objectives, three measures were established. The first measure quantifies individual station incident-based congestion. The second is a measure of the aggregate impact of individual incidents across freeway segments. And finally, the third measure is an index to quantify system-wide incident-based congestion.;These measures were tested on traffic data obtained from the metropolitan Detroit freeway system. The estimated system-wide off-peak incident-based congestion produces an average of 2.5 minutes of incident-based congestion per station per day. The congestion ranged from a low of 0.4 to a high of 10.5 minutes of delay per day over the 12 segments included in the study.