Traffic forecasts overestimated. by Andrew Herington

The explosive report from Infrastructure Australia “Spend more, waste more” makes damning criticisms of the record of State road bodies in assessing the economics of road projects. But it also contains some devastating information about trends in traffic projections.

The widely used engineering assumption is to project a continuous increase in future traffic growth of between 1.3% to 2%. All the work done for the East West Link by Veitch Lyster Consulting used this range of growth – based on this being the average for the last 17 years and would continue on the same pattern for the next 20 years. This extrapolation takes no account of changing trends but is used to justify the massive investment to expand road capacity.

The following table from page 24 of “Spend more, waste more” compares road agency forecasts for growth in road travel in the decade to 2011-12 versus what actually happened. Continue Reading…