Developing a Good Practice Guide on Travel Forecasting

Primary Author : Ian Clark

Organisation : Flow Transportation Specialists


This paper will document work carried out by Ian for NZMUGS, leading to a “good practice guide” being prepared, which was presented to the NZMUGS conference in September 2016. The work was in response to concerns expressed, both at AITPM and NZMUGS conferences, about inadequacies in the way the transport modelling industry was dealing with uncertainties in forecasting.


The work included a literature research on the accuracy of forecasts and the main sources of inaccuracy. It included surveys among NZ practitioners on current practices, leading to commentary on the topics of: toll roads, conservatism, transparency, optimism bias, length of forecast, the effects of new technology, looking back as well as forward, trip generation, consistency, and risk.