Abstract
IMPACTS is a computer image processing system with significant potential for incident detection. After a brief description of the system, the paper considers the role of such a system in incident detection. The problem of differentiating between congestion and the after effects of an incident are discussed. Data is presented showing how the output produced by the IMPACTS system can be used to measure the use of road space by moving and stationary traffic, and how this can be interpreted in terms of accidents. Examples are given, using real-time images from surveillance cameras on existing road networks, both motorway and urban. (A)