Travel classification

A trip leg is a section of travel by single mode with no stops. The relevant NZHTS variables used for calculating λ values were respondent age, travel mode, trip duration, trip origin activity and trip destination activity. Survey weightings and a person response status filter were applied to all trips within the analysis. λ values were calculated for major transportation modes in main urban areas (MUA), secondary urban areas (SUA) and rural areas (RA). A full definition of these areas is provided in appendix C. Given the New Zealand accessibility methodology calculates accessibility for travel from home, only home-based trips (trips which originated at the home) were included in the analysis (the use of a folded matrix, ie trip from destination to home was not included). The MoT conditions of use stipulate that analysis of travel trends for a subset of the data may only be undertaken when the sample size of the subset is over 120 trip legs or 60 persons.

The analysis of travel time includes multiple legs with each part of the trip chains using several modes although the travel has a single primary purpose. Travel time analysis can also be applied to trip chaining where trips of different trip purposes are joined, such as shopping on the way home from work. Consequently, the travel times are made up of walking elements within journeys, direct transfers between public transport services and indirect transfers requiring walking trips between public transport services. These are all counted as part of the trip. This captures the real time involved when selecting a mode or travel, rather than just the time by the primary mode of travel. The difference is likely to be significant for public transport services, where walk times at either end of the trip and between services may add significantly to the overall trip duration, but will also account for the effects of parking supply where a longer walk trip may be required. Only trips of more than 100m were captured, as the NZHTS does not gather information for walking trips of less than this distance.

λ values were calculated for travel to eight destination types; three of which were directly drawn from the NZHTS, while education trips were classified into approximate groupings based upon respondent age. A further category was created to capture trips for other purposes while some activities, determined to be less useful for this analysis, were not used. The survey activity classifications and new activity designations are outlined in table 13.1. Travel to all purposes by mode is also calculated, as a combination of all the categories from table 13.1 that were used in the new activity designations. When considering chained trips for multiple purposes there is usually a dominant trip purpose and linked trip purposes. In these circumstances it is assumed the characteristics of the trip are most influenced by the dominant trip purpose.

Table 13.1    Main data categories and descriptions in NHTS

NZHTS activity description

New activity designation(s)

Home

n/a (is origin for all trips)

Work – main job

Employment

Work – other job

Employment

Work – employer’s business

n/a

Education

Primary school

Intermediate school

High school

Tertiary education

Shopping

Shopping

Social welfare

Other

Personal business/services

Other

Medical/dental

Other

Social visits

Other

Recreational

Recreational

Change mode

n/a

Accompany someone else

n/a

Left country

n/a

Other

n/a

Overnight Lodgings

n/a