l rail-track new construction (RTNC) is estimated based on a proportion of RTCS. These 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 proportions were estimated from the same discrete railway sources, and varied from a high of 8.9% in Italy to an assumed low of 2.5% in developing countries - with an observed low of 4.0% in Japan. 6 The future levels of new construction for 2010, 2020 and 2030 were determined from the forecast values of RTRS, based on the same two components and methodology as for roads. Notes 1. The high (relative) ratios of PRCS-GDP for the industrialised and developing regions of Europe and Central Asia are believed (hypothesised) to be a result of communist central planning practises - which were not shared by China and North Korea. 2. The estimation process for base-year new construction is somewhat involved, and has no impact on forecast estimates. It is used solely as a point of comparison. In general terms, the expected level of maintenance spending on paved roads was estimated using a known (or assumed) value per pkm (ranging from USD 2 000-10 000, depending on GDPPC) times the number of pkm. The percentage of road spending devoted to new construction (% new) was then either known or assumed (depending on growth rate and GDPpc, with a range from 20% to 60%). 3. Data were primarily for individual railways in particular countries, using Annual Report values for rkm and net asset value for track-buildings-facilities (excluding rolling stock). Railways included: Queensland Rail (Australia), BNSF (United States), JR-East (Japan), Network Rail (United Kingdom), FS/RFI (Italy), CN/CP (Canada), DB (Germany). 4. Globe and Mail (2 November 2005), "Chinese railways plan to sell shares" (AP story), which reports planned spending of USD 61 billion over 2006-10, which in this model has been treated as plans for USD 10 billion/year over a 20-year period (2000-20), with r