Although Planning Support Systems (PSS) were, and are still, seen as very promising for improving urban planning practices, several decades of developing generations of such technologies have not bridged the implementation gap. To close this gap, a realistic evaluation of what works and what doesn’t is needed. In this paper Marco te Brömmelstroet present a framework to support such evaluation based on the ‘quality of planning’ concept. This framework is subsequently used to assess the added value of a state-of-the-art PSS. In a controlled experiment he tests if there are systematic differences on planning quality between an assisted planning process supported by a PSS and an unassisted planning process, without a PSS.
The results are presented in both descriptive and parametric statistics to provide a rich account of both systematic and non-systematic effects.
The outcomes show that the PSS brought a systematic added value to a number of dimensions of the quality of the planning process. It was especially strong in supporting the group process and in providing insights in mechanisms of urban problems to the participants. However, the quality of the outcomes was not systematically improved. These findings raise some interesting questions on what PSS aspire and what they currently achieve. Especially the importance of mediating between the instrument and participants seems an important element. The measurement framework was useful in supporting this analysis and could be further developed an used in research on PSS usability.