Immobility and Mobility Seen Through Trip‐Based Versus Time‐Use Surveys

Abstract

Nationwide Transport Surveys and Time‐Use Surveys both reflect the daily agendas and schedules of the reporting individuals and should therefore yield comparable indicators of travel behaviour; for instance: immobility rate (share of persons not leaving the home on any one day), daily travel time, and number of trips per day. These two surveys exist in three countries from the same time period: Belgium, France, Great Britain. The comparisons demonstrate that they tell parallel stories, but that the levels of the variables are significantly different with lower immobility rates and longer travel times reported in the Time‐Use Surveys. These surveys should therefore be integrated in the analysis of travel behaviour analysis as a crucial yardstick. In Europe, where Nationwide Travel Surveys are intermittent and not harmonized, the harmonised Time‐Use Surveys allow for crucial European‐wide comparisions across time and space.

Notes

1. If long enough, such travel should be described by two activities in a TUS: one trip made with a passenger and another one made, before or after, with no passenger. Frequently, however, the trips are not long enough to fill one (or more) ten‐minute slot each. Information on participants' travel cannot reveal ‘kiss and ride’ trips in those cases.

2. This assumption is based on examination of the first 25 daily activity reports of the 2200 individuals in the French dataset who report no travel and, at the same time, presences in different places. For 23 of them, there is no doubt that the respondents did leave their homes and make some trips, although the automatic data processing indicated the contrary. These mistakes fall into three categories. In some cases, the machine wrongly coded answers due to faulty recognition of keywords. Incomplete answers were another source of errors (e.g. “I am going out” without any other information). Finally, some answers did not distinguish between the activity and the trips (e.g. “I am going shopping” just followed by “I am preparing meal”); it would have been necessary to separate them clearly either in the time of the interviews or when the data was analysed (e.g. “I am going to the store; I am doing my shopping; I am going back home”).

3. It is clear that five‐minute trips are, by far, too numerous. Respondents round times. In the Belgian case, the only postal survey, this behaviour also led to many non‐responses when departure and arrival times were very close. Missing times were imputed according to distance and transport means, and this method has smoothed frequency distribution a little.