This paper focuses on the spatio-temporal aspects of congestion caused by an incident and the way in which this can be alleviated by a traffic management intervention. A kinematic wave model of traffic is applied to investigate the issues of congestion. Expressions are derived in closed form for a number of quantities of interest, including the maximum extent of the region, the time at which that occurs, relevant times for an intervention, and the effects of that on the size of the congested region. Special forms of these expressions are established for the case of the linear speed-density relationship, and calculations are performed to illustrate the application of the resulting analysis to examples of incidents both with and without intervention.
