Identifying factors to reduce car use by morning commuters

This research programme was undertaken between 1998 and 2003 in partnership with Dr Charles Sullivan of Capital Research, Wellington and Professor David Hensher of the Institute of Transport Studies, Sydney. It was funded by the New Zealand Government's research and development investment agency, the Foundation for Research, Science and Technology

Extensive consultation with government agencies, local authorities, the New Zealand Automobile Association and passenger transport providers, among others, led us to focus our research programme on managing and reducing car use by:

  • examining the "big picture" in which people make their travel decisions
  • developing an understanding of the constraints they face when they make travel decisions in various contexts, including:
    • weekday morning commutes (before 10 a.m.)
    • weekend travel
    • their children's journey to school
    • ascertaining people's response to various options to encourage a reduction in car use.

Our work on the latter led to a separate research programme trialling Walking School Bus networks in 4 Christchurch schools.

We designed and administered a sophisticated stated preference questionnaire of 613 car drivers in Auckland and Wellington in 1999/2000. In 2001, we revised this survey and administered it to 252 car drivers in Christchurch. We geo-coded the home to work distances for all 3 cities. We analysed the resultant database using standard statistical methods along with multinomial logit analysis. We compared our sample composition with the 1997/98 New Zealand Household Travel Survey (involving 8000 individuals) and found that our sample was broadly comparable.

Recognising that each of these regions (Auckland, Wellington and Christchurch) is different, we analysed each region separately, as well as developing a national model. We estimated the marginal effect of these policy tools, both "carrots" and "sticks", on an individual's decision to travel by car:

  • implementing a $5 or $10 toll ($2.50 and $5 in Christchurch)
  • implementing a 10 or 30 per kilometre vehicle registration surcharge
  • increased parking constraints:
    • a $5 or $10 surcharge on public car parking buildings ($2.50 and $5 in Christchurch)
    • implementing short term (P<120) on-street parking within .5 or 1.5 kilometres of the work place
    • increasing on-street parking charges to $2.50 or $5 per hour ($1.25 and $2.50 per hour in Christchurch).
  • improved frequency of passenger transport services, either in the "peak" periods or "off-peak" (not included in Christchurch)
  • improved / shortened trip times for passenger transport and high-occupancy vehicles
  • reduced passenger transport fares by 25% or 50%
  • improved routing of passenger transport services
  • improved cycle lane availability along 50% or 100% of the route to work / place of study (Christchurch only).

The major results quantifying the impact of these policy tools on car use were published in 2004 in the international journal Transport Policy.

A more detailed description of the variables used in the multinomial logit and nested logit analyses reported is available here [pdf].

From the above information and the contextual data we collected, we developed "profiles" of different mode users, identifying the characteristics of those car drivers most likely to switch to using passenger transport, being car passengers, car pooling or other modes (e.g. walking or cycling). We also identified perceptual barriers to using passenger transport in particular and "concrete" barriers to mode switching generally.

We also collected data on people's attitudes and ability to work a "compressed" work week and to "telecommute" (work from home) one or more days per week. We found 23% of respondents were receptive to these concepts.

Our survey also gathered information about car drivers' attitudes towards their cars, passenger transport, ride sharing (car pooling), and cycling (Christchurch only). For more about how these attitudes relate to peoples’ decisions, and about the design and structure of the car driver surveys, see the pdf files below.


Transport Policy paper 2004 (pdf)

Design of the survey (pdf)

Description and attitudes of sample population (pdf)

General results

Appendix A: Main questionnaire (Christchurch) and showcards

Appendix B: Supplementary (school) questionnaire and showcards

Appendix D: Maps showing toll cordon area (pdf)
Maps showing toll cordon area (zipped)