Abstract
In September 1990 the motorway orbiting Amsterdam was completed. This ring road together with some connecting highways, offer a number of alternative routes. For instance, travelling from Zaanstad to Utrecht, there is a choice to be made between the Coentunnel and the Zeeburgertunnel. The availability of these alternative routes offers the road authorities the possibility for guiding the traffic by using Variable Message Signs (VMS). The complex situation together with the high traffic volumes make it difficult to estimate the effects of VMS on the traffic. To get the necessary insight into these effects two simulation models have been developed. One model was based on the principles of METANET, the other on the principles of CONTRAM.