r vehicle ownership or road construction requirements. 22. Some of these countries/regions may in fact decide that they have over-invested in certain aspects of their road system, and may choose to allow some to deteriorate in quality. This model generally assumes that all replacement capital needs are met. 23. These are arc-elasticities calculated over the 10-year period, and are not equivalent to "marginal" (behavioural) elasticities. 24. This does not imply that such new construction is not economically desirable, just that public finance policy and constraints may not allow the "wealth/output- maximising" level of road new construction to occur. Several of the political/finance factors that might be limiting include: degree of political stability, degree of public corruption, lack of public revenue raising capacity, tax avoidance and high inflation. 25. This would not generally be practical along with the public finance factor. 26. The exception is the North American privately owned freight railways. 27. This does not imply that such new construction is not economically desirable, just that public finance policy and constraints may not allow the "wealth/output- maximising" level of road new construction to occur. 28. Bleijenberg (2002), p. 4. 29. The discussion at the Second Steering Group Meeting (12 December 2005) of the OECD Futures Project: Global Infrastructure Needs identified the importance of relating "needs" and "costs" to "benefits" - SO as to highlight that such requirements were economically justified (i.e. as cost-beneficial), rather than being engineering/ political "wish lists". 30. This is a finding of Canning-Pedroni (1999). 31. Conservative, as benefits are expected to exceed costs (by an unknown amount), on the maintained assumption that these relationships reflect some amount of public capital constrained behaviour. 32. This compares to annual GDP growth of 2.9% (2004-30), implying an arc-elasticity of vkm-to-GDP of 1.00. Note that this was not assumed, but resulted from the combination of