A traffic simulation approach to evaluating the benefits of incident management programs

Quantifying the impacts of ITS technologies is an important and necessary undertaking in order to justify the expenditure of public funds on ITS projects. For example, roadway incidents such as accidents, broken-down vehicles or other events that reduce the capacity of the facility impose a substantial cost to society when delays, congestion, secondary incidents, and environmental emissions are taken into consideration. These impacts can be substantially reduced through implementation of incident management programs. Significant benefits can be gained from early incident detection, quick response, provision of real-time traveller information and timely dispatch of emergence services. This can result in reducing traffic delays, secondary accidents, air pollution, and generally improve road safety and real-time traffic control. Recently, there has been a growing interest in developing traffic incident management plans for integrated freeway and arterial road networks and evaluating the effectiveness of such plans in minimising the effects of congestion. This is particularly important when evaluating incident management plans involving traffic being diverted to adjacent arterial networks. The impacts of incident management programs on network performance can be evaluated either in field studies or using traffic simulation. Field studies are generally expensive to conduct and they don't offer flexibility in investigating alternative scenarios. The use of computer modelling, and microscopic traffic simulation in particular, offers a more feasible and cost-effective approach, in which input conditions can be varied (e.g. to reflect incidents during peak and non-peak conditions) and their impacts on network performance evaluated