The network safety effects of dynamic route guidance

Driver information systems help drivers to navigate efficiently through a road network and avoid congestion. However, while a driver could save time by complying with a route switch recommendation, they might experience an increase in accident risk or cause other drivers to experience an increased risk. If this is the case, it may be worth considering the accident risk of different routes as part of the route recommendation process. The integration of accident predictive models within a traffic network model, designed to simulate route guidance, enabled these issues to be investigated. Dynamic route guidance, based on a minimum journey time criterion, is estimated in a congested, urban network to result in accident reductions of a similar proportion to distance reductions, but significantly less than journey time reductions. The effect of considering accident risk in route recommendations was investigated. Deterring drivers from minor roads or from high risk junction crossings failed to produce significant accident reductions when compared to route recommendations based on travel time alone.