Integration of a phone-based household travel survey and a web-based student travel survey

A significant share of transportation forecasting models are based on household travel survey data, frequently gathered through phone-based travel surveys. Over the last decade, these surveys have faced a variety of issues, namely a decrease in response rates and increases in potential sampling biases since their sampling frames are typically constructed using a list of land-line numbers. Although the weighting process can manage some of these issues, their scale is becoming a problem. In recent years, several experiments have been conducted in order to integrate multiple survey methods and data sources to obtain better quality databases. This paper reports on an experimentation conducted in 2012 in the region of Sherbrooke, in the province of Quebec, Canada. A web based travel survey was conducted among the regions' student population-in parallel to the large-scale household phone travel survey- in order to increase both the representativeness of the sampling frame and the response rate among 20-29 year-olds. This paper presents the methodology used to integrate both survey samples in order to create a more representative view of typical travel behaviors in the region of Sherbrooke. The paper demonstrates that by combining the samples, we succeed in reducing heterogeneity in sampling rates among population segments which translates into an increase in trip rates (global and transit) for the target population. Challenges related to the combination of survey methods and samples are discussed.