Samenvatting
Recent results of a study into the effects of variable message signs raise questions on the feasibility of using aggregate parameters and indicators for evaluation purposes, as required by European guidelines. Using the Routekeuze-Informatiesysteem Amsterdam (RIA) evaluation as an example, this paper deals with a number of methodological problems, which must be faced when evaluating traffic management measures. A few solutions which may alleviate these problems are outlined. (A)