Beyond the Typical Day: Evaluating Multi-Day Travel Behaviour Through a Core–Satellite Survey Approach in the Greater Toronto and Hamilton Area

This study evaluates the need for extended-duration travel surveys and builds the case for a core-satellite survey design in capturing multi-day travel behaviour. Leveraging the 2022 Transportation Tomorrow Survey (TTS) as the core, two satellite surveys were conducted in 2023 and 2025 in the Greater Toronto and Hamilton Area (GTHA), Canada, using GPS-based data collection methods. These satellite surveys targeted multi-day observations to assess how much additional behavioural insight can be gained beyond a typical one-day survey. This paper details the survey design and implementation of the 2025 cycle and compares travel patterns observed across the core and satellite datasets. To guide efficient multi-day survey design, Shannon’s entropy is used to quantify variability in individual travel behaviour across varying observation lengths and sample sizes. The findings reveal that while increasing both the number of observation days and the sample size enhances the informational value of the data, the marginal gains diminish beyond a certain point. Most of the day-to-day variability in travel is captured within the first five weekdays, suggesting that a five-day observation window and a sample size of at least 600 individuals can provide a sufficient balance between behavioural coverage and statistical robustness. These results support the use of targeted satellite surveys to complement large-scale, typical-day surveys in a cost-effective and methodologically sound manner.