Abstract
GPS-equipped smartphones provide new methods to collect data about travel behavior, including travel survey apps that incorporate automated location sensing. Previous approaches to this have involved proprietary or one-off tools that are inconsistent and difficult to evaluate. In contrast, e-mission is an open-source, extensible software platform that consists of (a) an app for survey participants to install on their Android or iOS smartphones and (b) cloud-hosted software for managing the collected data. e-mission collects continuous location data, user-initiated annotations, and responses to contextual, platform initiated survey questions. New studies can be set up using the existing University of California, Berkeley, infrastructure with no additional coding, or the platform can be extended for more complex projects. This paper reviews the requirements for smartphone travel data collection, describes the architecture and capabilities of the e-mission platform, and evaluates its performance in a pilot deployment. The results show that the platform is usable, with over 150 installations in a month; stable, with over 85% of users retaining it for more than 3 days; and extensible, with interface and survey customizations accomplished in a little over a week of full-time work by a transportation engineering researcher. We hope that e-mission will be a useful tool for app-based data collection and will serve as a catalyst for related research.
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