New Zealanders’ trip chains and tours

In 2003, we reformulated the 1997/98 NZHTS trips dataset into trip chains and tours. "Trip chains" describe how New Zealanders link their travel between "significant" locations, namely home, work or education, and other activities where they remain more than 90 minutes. "Tours" describe how New Zealanders link their trip segments in a round trip that begins and ends at home.

The results reported from the NZHTS (and indeed many other household travel surveys internationally) are often based on 'trip legs' or 'trip segments', commonly referred to as 'trips'. Such 'trips' often differ from what most the general population would consider as a 'trip' (which is closer to what we will define as "trip chain"). For example, if I drive home from work but stop briefly twice (e.g., to get a newspaper, and later to pick up children), that travel comprises three trip legs but only one trip chain. If the trip legs are each relatively short (i.e. < 2 km), then policy- or decision-makers might consider that some or all could be replaced by walking, when in fact, as part of the longer trip chain, the mode for each leg cannot be individually substituted. Furthermore, this does not take account of the fact that, once selected, a mode is generally used for both the outward and return journey, in what we define as a "tour".

Our reformulation of the 1997/98 NZHTS dataset into trip chains and tours led to a greater understanding of New Zealanders' travel behaviour, particularly their use of the car. Our work helped to correct misunderstandings about the nature and frequency of short trips; enabled better quantification of the potential for change from short car trips to public transport and active modes (walking and cycling); and enabled new and improved performance measures about short trips.

In 2008, based on our previous reformulation of the 1997/98 New Zealand Household Travel Survey dataset, we reformulated the 2004-07 Ongoing NZHTS trips dataset into trip chains and tours (round trips beginning and ending at home). Using the reformulated datasets, we made comparisons between New Zealanders' travel patterns in 1997/98 and the four-year period of 2004-07 and commented on the emergence of some trends in New Zealand travel behaviour.

Among other things, in comparing 2004-07 with the earlier 1997/98 dataset, we found that:

  • The mean number of trip chains per day (2.3) and the mean number of tours per day (1.3) were essentially unchanged.
  • Both trip chains and tours showed an increasing propensity to have fewer segments.
  • Vehicle-driver-only trip chains increased significantly to 53% from 48% of all trip chains. Vehicle driver only tours increased significantly to 50% from 47%.
  • The vast majority of trip chains and tours are 'non-work/non-education' tours (e.g. personal business; social welfare; social; recreational)
  • Walk-only trip chains declined to 11% from 13%

Formal recognition of the importance of our alternative units (trip chains and tours) for monitoring trends has come recently in the Ministry of Transport's Transport Monitoring Indicator Framework. Two of the travel behaviour indicators in the framework will be based on trip chains.

Reports

O’Fallon, C., & Sullivan, C. (2009). Trends in trip chaining and tours: analysing changes in New Zealanders’ travel patterns using the ongoing New Zealand household travel survey. Wellington:  New Zealand Transport Agency. Research Report 373 (pdf)

O'Fallon, C. & Sullivan, C. (2009). New Zealanders' travel patterns: trends in trip chaining and tours. Presented at 31st Australasian Transport Research Forum, Auckland, October 2009. Paper (pdf)

O'Fallon, C. & Sullivan, C. (2005). Trip chains and tours: definitional issues associated with household travel surveys. Presented at 28th Australasian Transport Research Forum, Sydney, September 2005. Paper (pdf)

O’Fallon, C., Sullivan, C. (2005). Trip chaining: understanding how New Zealanders link their travel. Wellington: Transfund New Zealand. Research Report No. 268 (pdf)

Sullivan, C. & O’Fallon, C. (2004). Understanding the nature of “short trips” in the New Zealand context. Presented at Towards Sustainable Land Transport Conference, Wellington, November 2004. Paper (pdf)