21: Ensuring Quality in Stated Response Surveys

While most travel surveys ask respondents about their existing behaviour or attitudes, there is a growing requirement for modelling and policy purposes to obtain information about how travellers are likely to react in new hypothetical situations, where there is little existing experience on which to make choices. In the field of traffic policy, the demand for innovative traffic solutions has grown significantly as a consequence of increasing traffic problems. Typical examples of such innovative traffic solutions are: new pricing systems e.g., congestion pricing), new vehicles (e.g., new environmental friendly motorbikes (Sammer and Thaller, 1997), electric cars), new public means of transport (e.g., Swiss Metro (Abay, 2000), German Transrapid), new traffic regulation strategies (e.g., access to the central business district only by specific cars), etc. For the transport user, these innovative traffic solutions represent hypothetical markets. The respondents in the various surveys usually have no first-hand experience of the situations offered as alternatives from which to choose.