Traffic Forecasting at 'Strategic', 'Tactical' and 'Operational' Level A Differentiated Methodology Is Necessary

In this paper we discuss why traffic forecasting is such a difficult endeavour, and point at alternatives to the current widespread use of traffic models almost independently of the problem faced by the planners. It will be argued that it is inherently impossible to make exact predictions about the magnitude of general' traffic growth 20-30 years ahead, since many of the influencing factors depend on inherently unpredictable geopolitical trajectories as well as contested political decision-making. Due to the context-dependency of each particular planning situation, it is also hardly possible to make exact, quantitative predictions about the impact of implementing a specific infrastructure project, compared to doing nothing'. We propose separating the so-called strategic, tactical and operational levels of traffic forecasting into three distinct methodological approaches reflecting the different degrees of openness and closure of the systems at hand: scenario analyses at the strategic level; theory-informed, mainly qualitative analyses supplemented with simple calculations at the tactical level; while more traditional micro-simulations should be applied only at a detailed operational level.