This Round Table is one of a series of research events to discuss tools to improve transport planning. It addressed the macroeconomic effects of transport infrastructure policies, and aimed at identifying analytical and empirical tools that could determine the overall volume of public expenditure for transport infrastructure investment. It also sought to identify state-of-the-art methods for assessing the macroeconomic impact of transport infrastructure investment. Macroeconomic studies help to identify overall funding needs for infrastructure investment and allow overall rates of return on investment expenditure to be derived. Several effects of transport infrastructure investment, such as the impact on the efficiency of logistics systems, or the growth effects of induced changes in the pattern of urbanisation, are not (or not fully) captured by other planning instruments. Background papers were provided by David Canning (Harvard University), Charles Hulten (University of Maryland) and Andreas Kopp (OECD/ECMT Transport Research Centre).