This licentiate thesis is about the provision of transport infrastructure a nd the regional impacts of such provision. Three different techniques have been investigated that can be used for the assessment and forecasting of the effects of infrastructure: transport demand models and parametric and nonparametric econometric estimation techniques. The main interest is focused around the regional effects of the Öresund fixed link, which was opened on July 1, 2000. The thesis is a collection of three papers plus a general introduction: papers 1 and 2 are concerned with the effect of accessibility in the transport networks on productivity on an individual firm level. In paper 1, a translog cost function, extended with an accessibility variable, is estimated for 24 business aggregates using panel data techniques and tests on a dataset covering single workplaces in Scania over the years 1990-98. The results are not conclusive, and cannot be used for forecasting of the after-situation. In paper 2, a non-parametric method, propensity score matching, is applied on the same dataset to test if productivity differs in high accessibiliby areas compared to those with low accessibility, while controlling for other differences between firms. The result here is the same as in the first paper: for no business there is a significant difference in productivity that can be related to accessibility. In paper 3, a framework for the external validation of models of transport, land use and environment is developed, with a focus on transport forecast models. The scenario assumptions and forecast results of earlier models are presented and compared. A before-and-after database under construction for the Öresund region is also presented, to be used for validation of such models.