Household travel surveys response rates are decreasing. Weighting aims atreducing the impact of non response, but it is always necessary to postulate that people with some socio-demographic characteristics who do not respond to a survey have the same behaviour than people with the same socio-demographic characteristics who respond. But evidence seems to indicate that it is not always the case for travel. To reduce this bias of non-response, we initiated a project of a web survey in parallel to the household travel survey conducted by interview in Lyon. The idea is to propose to households who refuse to respond or are not reachable after a certain number ofattempts to respond using the web. This new and interactive mode of data collection offers respondents the possibility to choose a more appropriatemoment to complete the questionnaire, and does not require to set an appointment with the interviewer. The implementation of a web survey raises specific problems, in terms of design and administration of the questionnaire. Last but not least, if the launch of a web survey makes it possible to study behaviours little represented up to now (hyper-mobile households, with shifted schedules), the question of data comparability remains. Around 370 full web questionnaires have been stored in a database. That represents a global response rate of 8.5%, remaining that some households are not able to connect to internet at home or at their working place and that the survey was proposed only to a portion of households who have refused or who were not reachable after 8 attempts. The main objective of the data analysis is to assess the potential of the web for households travel surveys. Results indicate that short trips are often omitted in web survey. The comparison is therefore not limited to the number of trips, but the number oftours (succession of trips and activities between the exit of home and the next way back) is also considered in order to assess if differences are mainly due to short trip omissions or if some tours are also omitted. The comparison follows with trip/tour characteristics like transport mode, purpose, distance, duration, time of day. To take into account socio-demographics difference between populations which might generate different behaviours, the working population was focussed on, which constitutes 70% of the web sample. Data show that internet respondents move less than respondentsto interview. This slighter mobility concerns the daily number of trips and tours. The result remains even when focussing on working persons, to limit socioeconomic differences between the two samples. This gap can be explained by a triple effect: a higher immobility of the internet respondents, a lower statement of their daily trips and, in a certain extent, for working persons, a low number of trips by tour. An analysis by mode or purpose shows that the differences concern mainly a lower proportion of walking,mobility by car slightly weaker for working persons, and a participation in providing transport for others or leisure activities sharply weaker. For the covering abstract see ITRD E145999
Samenvatting