This project explored the potential of archived multi-day GPS data to expand the understanding of travel-time reliability. While reliability is often observed and considered at the system or segment level, travel-time uncertainty is also experienced at the household and trip level. Any move toward incorporating reliability into regional travel models will necessitate a re-examination of travel-time variation at more disaggregate levels. The analysis uses multiday vehicle-based GPS data analyzed within the Transportation Secure Data Center (TSDC). 

There were three major goals for the research. The first goal was to consider the ways in which multiday GPS data could be translated into data on reliability. The second goal was to explore relationships between trip- and household-level travel-time reliability and related trip, household, network, and urban location factors. The third goal involved use of the topic of reliability as a case study to test the usefulness of the TSDC in its current form for academic research.

The results are found in Chapter 1 of the online report below:

http://www.fhwa.dot.gov/planning/tmip/publications/other_reports/multiday_gps/fhwahep15026.pdf