The Dutch national transport policy is focused on using roads more efficiently in order to reduce congestion. Variable message signs (VMS), gating systems, dynamic route information panels (DRIPs) and dedicated lanes on highways are well-known examples. A lot of studies investigate the effects of these measures on travel behaviour. Recently, an investigation has been finished which examines the environmental effects of these measures: noise, air pollution, soil and water pollution, external safety, energy use, landscape and nature. This research is the first step on this subject. The paper deals with the approach of the subject, the outcomes and proposals for policymakers. The main conclusions are: (1) The environmental effects of traffic management measures in order to optimise the use without expanding the capacity (for instance DRIPs) turn out to be most positive; and (2) expanding the capacity using traffic management "tailor made" (for instance, dedicated lanes), is less positive for the environment, but the environmental effects are less negative compared to expansion of the transport network. (A)
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