 world the responsibilities of the nation state are being "hollowed out" upward, i.e. where greater oversight responsibility is assumed at the supranational level. This is because states have increasingly sought to establish international mechanisms to facilitate and mediate their relationships as such inter-state relationships have become more complex. In this context, supranational bodies, such as the EU and WTO, will become increasingly important with respect to policy issues and the terms of engagement. For example, the EU plays a particularly important role in the European water sector, as it is instrumental in setting standards and requirements that have a significant impact on water services and infrastructure. The "hollowing out" of the nation state is also taking place downward, as responsibility for a range of infrastructure service functions are devolved away from central government either to local or regional bodies, or delegated to state or non-state agencies. Making the right decisions in this increasingly complex institutional environment will become ever more challenging. Improving the policy toolbox Finally, an important aspect to emerge from the sectoral chapters is the need to improve the tools at policy makers' disposal. Among the items addressed in these chapters are the quantitative and qualitative inadequacy of the infrastructure-related statistics and data sets currently available; the utilisation of more sophisticated cost/benefit analysis, notably methods that include consideration of indirect effects of infrastructure development and not just the direct effects; more widespread use of accrual accounting for infrastructure cost, depreciation expense and financing costs; and the potential of network-wide asset planning and project identification as well as comprehensive asset management and performance measures. 6. The road ahead The economic, demographic, political and technological changes that the next two to three decades are set to bring will have significant implications for infrast