Vehicle occupancy in New Zealand's three largest urban areas

As in several other countries, vehicle occupancy in New Zealand has been gradually declining. The Government's Energy Efficiency and Conservation Strategy (2003) identified increasing vehicle occupancy rates as one means of reducing energy use and CO2 emissions from transport.

Measurements of vehicle occupancy are often by simple observation of vehicles on the road. Such measurements are naturally unable to relate differences in occupancy to variables such as trip purpose, driver demographics, and so on. Our analysis describes the vehicle occupancy in terms of such variables in New Zealand's three largest urban areas (Auckland, Wellington, Christchurch) by using a large nationwide survey, the New Zealand Household Travel Survey 1997/98. The analysis is extended, where possible, by linking the driver information to travel information from others in the same household. Hence, contrasting patterns may be found among several different types of vehicle occupancy: single-occupant vehicle, household adult passengers, household child passengers, non-household passengers.

Implications for transport policy are considered, by comparing our results both to overseas research on vehicle occupancy and to our recent stated choice experiments in the same three New Zealand cities. Our stated choice research with morning commuters found a significant effect of trip-time reductions from a high occupancy vehicle lane on car-pooling in Auckland. Mode choice was also affected by other variables related to occupancy, particularly driving children to school.

Reports

The paper was presented at the Australasian Transport Research Forum 2003 in Wellington, New Zealand. The working paper is available as a pdf document:

The study on vehicle occupancy is being updated using the 2004-2008 Ongoing Household Travel Survey dataset and should be published in early 2010.