Special issue: Network reliability and transport modelling

With increasing demands for better and reliable service due to improvements in the quality of life, many systems (such as the communication networks and drainage systems) have incorporated "reliability analysis" as an integral part in their planning, design and operation. However, very little attention has been given to the reliability analysis of road networks. On the other hand, Intelligent Transport System (ITS) has developed rapidly in recent years. Impetus was received from the investigation of the effects of ITS on two types of road congestion; namely, recurrent and non-recurrent congestion. The former is referred to as the predictable traffic conditions caused by an excess of demand over supply, following a defined pattern, e.g. peak period traffic and seasonal variations. The latter includes non-recurrent congestion situations resulting from a temporary reduction in the capacity of a length of road due to accidents, bad weather, construction works or other short-term disruptions to traffic flow. The introduction of ITS and the concept of "reliability analysis" has generated an urgent need for better understanding of road network reliability under recurrent and nonrecurrent congestion scenarios.