Development of marginal costs for heavy vehicle bridge usage

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Publication details

Austroads 2012, Development of marginal costs for heavy vehicle bridge usage, Austroads research report no. AP–R407-12, report prepared by N lake, T Martin & T Thoresen, Austroads Ltd., Sydney, NSW. ISBN: 978921991318.

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This report develops approaches that estimate the marginal cost (MC) of bridge wear for heavy vehicle usage and estimates the availability and reliability of the data needed to use these approaches. Two approaches were examined. The first was an engineering approach based on the life-cycle costs (rehabilitation/capital and maintenance) of bridge wear at a given level of heavy vehicle traffic. The second was an econometric approach based on historical bridge expenditure (rehabilitation/capital and maintenance) and heavy vehicle bridge usage data. Both approaches determine a bridge wear cost relationship with heavy vehicle bridge usage from which the MC of bridge wear can be derived.

A methodology to estimate both the short-run marginal cost (SRMC) and the long-run marginal cost (LRMC) was defined using the engineering approach. The methodology relies on the provision of adequate, accessible and reliable traffic and cost data, and the estimation of fatigue life. The econometric approach has the potential to estimate SRMC and LRMC, although this approach has the limitation that it may not reliably make these estimates for load increases beyond those captured by historical cost and traffic data due to the assumptions needed to make these estimates.