The network safety effects of dynamic route guidance

Driver information systems help drivers to navigate efficiently through a r oad network and avoid congestion. However, while a driver could save time b y complying with a route switch recommendation, they might experience an in crease in accident risk or cause other drivers to experience an increased r isk. If this is the case, it may be worth considering the accident risk of different routes as part of the route recommendation process. The integrati on of accident predictive models within a traffic network model, designed t o simulate route guidance, enabled these issues to be investigated. Dynamic route guidance, based on a minimum journey time criterion, is estim ated in a congested, urban network to result in accident reductions of a si milar proportion to distance reductions, but significantly less than journe y time reductions. The effect of considering accident risk in route recomme ndations was investigated. Deterring drivers from minor roads or from high risk junction crossings failed to produce significant accident reductions w hen compared to route recommendations based on travel time alone.