Statistical Bulletin Trn/2005/2
Scottish Household Survey Travel Diary results for 2003
14. Weekday adult trip rates (rates per adult and rates per household) ( Table 22)
14.1 Table 22 contains "experimental" statistics, based on the five years 1999 to 2003 taken together. These results have been provided for illustrative purposes: they are not considered to be "definitive" for the reasons given in section A4.6, so should be regarded as rough estimates. Table 22(a) shows the estimated number of trips per weekday per adult. For example, the first figure in the first row shows that an average of 2.15 trips per weekday per adult were reported in the survey (including imputed journeys). The remaining figures in this row have been scaled up by a factor of about 1.41 in an attempt to compensate for under-reporting (see section A4.6 for more details). The "scaled up" results show that an average of about 3.02 trips per weekday per adult were made: about 2.71 "Home based" (trips where either the origin or destination was home) and about 0.31 "Non-Home based" (where neither the origin nor the destination was home). The equivalent figure for weekends would be 2.62 trips per day per adult (1.82 scaled up by a factor of about 1.44).
14.2 Table 22(a) shows how the weekday trip rates per adult vary with the main mode and purpose of travel. For example, using the "scaled-up" results, an average of about 2 trips per weekday per adult were made by car or van compared with only about 0.35 by public transport. About 0.86 trips per weekday per adult were made for commuting purposes, compared with about 0.15 trips per weekday per adult for business purposes (see section A3.3 for details of how "journey purpose" is defined). As would be expected, the commuting trip rate per adult was higher for those aged 16-59 in employment (about 1.61); other people made relatively few commuting trips. Trip rates per adult tended to rise as the number of cars available for private use to the household increased: from about 2.18 trips per weekday per adult in households without access to a car for private use, to about 3.17 per adult for households with access to one car, and about 3.66 per adult for households with access to two or more cars.
14.3 The adult weekday trip rates per household, shown in Table 22(b), have been estimated by multiplying the weekday trip rates per adult in Table 22(a) by the relevant ratio of the total numbers of adults and households (overall, there are about 1.8 adults per household; the ratio rises from 1.4 for households with no cars to 2.4 for households with 2+ cars, because the latter are larger, on average). Table 22(b) shows that the estimated number of adult trips per weekday per household is about 5.35. Similar patterns to the weekday trip rates per adult can be seen. For example, more trips are made by car or van (3.54 adult trips per weekday per household) than by the other modes. On average, households with 2+ cars had about three times as many trips as households without access to a car.
14.4 Some of the figures in Table 22 differ greatly from those which were published in the previous edition of this bulletin. Unfortunately some of the figures published previously were calculated incorrectly. The biggest changes are to the figures on the "0 cars" and "2+ cars" rows, in both parts (a) and (b) of the table. Compared with the previous estimates, the "0 cars" figures are larger, and the "2+ cars" figures are smaller, and the differences between the trip rates for these two categories are smaller than had been shown by the incorrect figures published previously.