Measuring Traffic Congestion

This paper examines traffic congestion, particularly in light of the growing public emphasis on the cost of congestion. Traffic behaviour and management are discussed in the context of congestion and its various causes. The importance of queues is highlighted. The separate roles of intersections and links are explored. It is suggested that many fallacies and misconceptions surround congestion, and doubts are placed on current estimates of the cost of congestion. To overcome this situation, an alternative approach to congestion assessment is proposed with an emphasis on queue formation and catastrophe theory. The new approach provides the basis for a straightforward and implementable way of estimating the occurrence and cost of congestion. The author suggests that some current practices could distort road investment priorities.