g road assets that deteriorate over time. A smaller component actually goes to augment the road capital asset value. Over the entire 2000-30 period, a declining ratio of road capital asset value-to-GDP is forecast - which implies an increase in the productivity of road transport infrastructure. Rail-track infrastructure requirements (2000 to 2030) While the same economic factors also determine rail-track infrastructure requirements, government policy to affect modal shift (from road to rail) has an important influence. Rail-track infrastructure requirements (new construction) of between USD 49-58 billion/year are forecast between 2010-30, with a range of +20% of this amount subject to deliberate policy intervention to fully implement/ accelerate rail upgrading to achieve modal shift targets (or not, as the case may be). INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 4. KEY FACTORS DRIVING THE FUTURE DEMAND FOR SURFACE TRANSPORT INFRASTRUCTURE Policy implications Relevant policy implications arising from these forecasts, which might be usefully addressed in future work in subsequent phases of the OECD Futures Project, include: Infrastructure benefits are expected to exceed infrastructure costs. Benefits from road transport infrastructure will be more heavily weighted to economic/ productivity benefits, while benefits from rail-track infrastructure will more likely be derived from social/environmental outcomes. Economic/business model. The current model, reliant on annual appropriations control of general tax revenues, will come under intense stress in coping with the heightened fiscal demands of infrastructure requirements. Greater reliance on specific taxes (e.g. hypothecated fuel taxes or road fees) and direct road user charges (e.g. heavy vehicle charges, tolls) will need to be encouraged. Governance/funding of infrastructure. In addition to resolving the funding issue for surface transport infrastructure there is the governance issue, which must address 