How planners' use and non-use of expert knowledge in land use and transport planning affect the goal achievement potential of plans? Experiences from three Scandinavian cities

Changing urban development in more sustainable directions poses numerous challenges for planning practitioners. Expert knowledge could be helpful for planners aiming at facing up to these challenges by developing innovative ways of meeting seemingly contradictive objectives and solving planning problems. This paper examines how planners' use and non-use of expert knowledge affect the content and goal achievement of plans, and discusses how changes in planning practice and research practice can contribute to improve goal achievement potentials. Goal achievement potential refers to whether the plans (if implemented) contribute to achieve defined objectives, which in this paper concern transition toward more sustainable mobility patterns and reduction of traffic volumes. The expert knowledge in question concerns how land use and transport systems developments influence traffic volumes in urban regions. Even if diffusion of research-based knowledge have been investigated, planners' use of expert knowledge when making plans, and the effects on the content of plans, have gained surprisingly little attention in planning research. Over the past few years, interesting discussions concerning this issue have emerged, but few empirical studies have been presented. The research in this paper involves case studies of strategic plan-making processes in three Scandinavian cities. A main finding is that whether the expert knowledge in question is used or not, and how it is used, indeed affect the goal achievement potential of plans. This knowledge is the main basis for many planners' knowing and acting, and fundamental for land use and transport planning being coordinated and for traffic-reducing measures being included in the plans. The knowledge is used for explaining cause-effect relations, and as arguments for selecting traffic-reducing measures. All examined plans also include strategies reducing their goal achievement potentials. This happens through a mix of mechanisms. When competing objectives or ideas seemingly call for traffic-increasing measures, the planners do not use the expert knowledge in question for explaining that these measures reduce the goal achievement potential of plans, for several reasons. It may seem as if the knowledge sometimes is ousted when it challenges the contextual agenda. Further, planners do not turn to written or research- based sources of knowledge for help in solving their planning problems. Instead, they rely on their embedded professional knowledge, which is sometimes outdated or misleading. It is found that changing towards land use and transport systems developments contributing to more sustainable mobility patterns requires considerable efforts from planning practitioners, as well as from planning researchers