A Strategic Transport Model-based Tool to Support Urban Decision Making Processes Introduction -need to Support Urban Decision Making Processes

The complexity of decision making processes in urban land-use and transport systems raises the demand for an efficient support tool. Such a tool was developed at TUW-IVV in a modular structure: a strategic transport (and land-use) model, a set of policy measures, a set of objective functions and different optimisation methods. The suitability of the TUW-IVV concept has been proved in several EU research projects. Within these projects all modules were continuously improved. Some examples: taking into account user benefits for non motorised modes in cost benefit analysis, considering constant travel time budgets, use of new optimisation methods. The TUW-IVV concept has several advantages: low data requirement, easy to implement as well for small as for big cities, short run time and compatible with more detailed models. Reliable decision support tools are available. But in reality most land-use and transport relevant decisions are made bypassing the planning administration. A future task will be to improve policy maker awareness about supporting tools. Interaction between transport planning, land-use planning and regional economy is highly complex. As a result even effects caused by the change of a single policy measure can be difficult to understand. Especially as, in reality, most decision making processes have to consider a combination of different policy measures. In addition numerous different protagonists are involved on different administrative and legislative levels. Politicians as well as planners make their decisions under these circumstances (Fig. 1). A tool, which predicts effects caused by different possible actions, is highly welcome in this situation. To asses long term effects of numerous competing possible decisions, extreme accuracy of the predictions is not the crucial matter. Rather characteristics like availability of necessary data, low expenditure to set up the model and a short run time are essential for the suitability as a tool to support urban decision making processes.