The aim of this report is to contribute to the economic analysis of new high speed rail investment projects requiring public funds. The economic evaluation of projects can help governments to obtain a clearer view of the expected net benefits of different lines of action, as it attempts to identify the projects which really deserve the sacrifice of other social needs competing for the same public funds.

We analyze the circumstances under which society may benefit from investing in high speed rail, and when it is sensible to delay the investment decision. The high speed rail network may be built gradually, adding new lines once the economic evaluation of projects shows a positive social profitability.