This paper describes an intelligent interface developed to assist in the task of collecting detailed information regarding daily travel behaviours. The computer-assisted telephone interview (CATI) system, developed by the MADITUC Research Group for the Montreal large-scale travel surveys, is structured in three main screens (household, person and trip) and assists the interaction between an interviewer and a respondent during a phone interview. This tool enhances the quality of the data collected by performing real-time validation of the spatio-temporal details related to travel behaviours. In addition to describing the design of the CATI tool, this paper proposes some empirical measurements associated with the CATI use by the interviewers owing to the processing of numerical logs saving every action taken by the user during an interview. Using these data, variables significantly influencing interview duration are identified.