cal. The addition of new infrastructures to create a network, however, allows considerable productivity gains by extending the use of existing infrastructures to everyone. Subsequently, when the network is largely completed, the addition of new infrastructures again has only limited impact, if any, on private sector productivity. But such additions can still have an effect on the economy, namely by making the regions in which infrastructures are abundant more attractive and thereby enhancing their competitiveness. This in turn may give rise to relocation of factors of production among regions. Attractiveness is therefore a factor, irrespective of whether the infrastructures lead to productivity gains. The political dimension of this process is clear, since it will benefit some regions at the expense of others as they compete among themselves to attract labour, capital and know-how. From an overall economic perspective, this highlights the importance of conducting cost/benefit analyses for large projects that also take into account the loss of attractiveness of those regions not concerned by the new infrastructure. Attention should also be paid to consumers' intrinsic evaluation of the infrastructure since this can generate knock-on effects, for instance in the form of higher property prices. What of the eventual economic benefits of infrastructure? As more and more networks are completed, for example, will the economic benefits stagnate? Generally, this seems less likely. As Stamford points out in his chapter on land transport, notwithstanding political factors that may have resulted in some INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 1. A CROSS-SECTORAL PERSPECTIVE ON THE DEVELOPMENT OF GLOBAL INFRASTRUCTURES TO 2030 uneconomic projects going ahead, it can be assumed that in OECD countries most of the transport infrastructure investments over the past 20 years have been cost-beneficial; and that it is very likely that some amount of cost-beneficial new 