QUESTA is a scenario-development project that was carried out by a team within the Netherlands' Ministry of Transport, Public Works and Water Management. The aim of the project was to develop descriptions of possible future developments inside and outside the Dutch traffic and transport system. RAND Europe assisted the project team by providing advice and support in different phases of the project on an as-needed basis. One of RAND Europe's major contributions to the project was the development of a system diagram for the policy domain of traffic and transport (a task that was performed jointly with TNO Inro). The diagram represents the traffic and transport system as a system composed of three inter-connected markets, each of which experiences a dynamic interaction between its own demands and supplies. The three markets are: a trip market, a transport market, and a traffic market.