Kulash produced a model similar in concept to that described above but with a level of disaggregation in the procedure prior to aggregation for final national projection. This study parallels a continuing discussion in the USA and elsewhere into the effects of car ownership on transit usage but was unusual in its advocacy of large scale investment in public transport facilities as a dynamic influence on levels of auto ownership and use. The use of forecasting methods in Australia provides an interesting comparison with other developed countries. In 1971, 71 per cent of the Australian population resided in the seventeen largest cities. Despite a recent trend towards increased Federal Government involvement in road transport, trunk roads remain largely the responsibility of the six Australian states. The widespread use of extrapolatory curves in Australian studies exposes the main weakness of this method, namely the assumptions on and effect of saturation level.