n 2000 to USD 1 342 billion in 2030, a cumulative growth of 110% over 30 years. The ratio of rail capital stock-to-GDP increases slightly from 1.1% to 1.2% over that period, which is only impressive in light of the downward trend of this ratio for road capital stock (for industrialised countries). Risk factors for rail new construction The results above are based on very subjective assumptions, which might reflect "wish lists" to the extent that these are embedded in EU TEN-T programme and Chinese plans for railway expansion. Unlike road construction - for which there is a clear consumer-revealed preference through autonomous traffic growth and vehicle ownership - rail construction is largely driven around the world by government policy. 26 There are many factors that might prevent (if desirable) or render unnecessary (i.e. make undesirable) the forecast levels of new construction on rails. These include: Conscious government policy to constrain/reduce public expenditures - (and clearly antagonistic to "sustainability" concerns which are addressed next): Up to (perhaps) 20% of the rail new construction (i.e. USD 10-12 billion/year) could be diverted with some attendant (but possible bearable) consequences in terms of deteriorating overall rail infrastructure quality and continued modal shift toward road vehicles (as perhaps did happen inadvertently over 1970s-90s in many countries).27 Land use and environmental limitations of rail infrastructure expansion, especially the difficulty of right-of-way access around urban areas. 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 Improvement in rail maintenance and management (especially efficiency enhancements and extension of infrastructure life): Up to (perhaps) 5% of the rail new construction (i.e. USD 3 billion/year) could be saved in the long run. Lower-than-anticipated growth in HSR use and rail freight traffic. Conversely, there a