Project Summary
The Institute of Transportation Studies at the University of California, Irvine, recently developed for ARB a tool that merges vehicle measurements with a highway network layer in order to form a picture of roadway vehicle activity. This system is called the California Vehicle Activity Database (CalVAD).
CalVAD is an excellent tool as it stands, but it is missing any information on non-highway vehicle activity. This proposed project would add arterial traffic flows to CalVAD. The initial focus will be to add HPMS data to CalVAD that will enable straightforward bounding box and area queries that rely on the PostGIS extension to PostgreSQL to be performed. Although the 2007 HPMS data are loaded into the CalVAD database, and can be queried along with other data, these data do not have any geographic referencing associated with each link. The key technical hurdle will be addressing the lack of georeferencing in that data set, as well as anticipating possible successors to HPMS data that might become available.
Arterial roads are where the majority of roadway vehicle activity takes place, but there is scant measurement of these flows. The primary barrier is the cost of measurement. Caltrans can justify putting loops into the state highways and installing weigh in motion stations at key locations, but local traffic authorities cannot justify installing count stations on every road. Even producing counts for the annual HPMS survey is limited to major arterials, with minor arterials and other roads allowed to be sampled every 3 years or more. And yet, without deploying any hardware, Google has managed to produce reasonably accurate estimates of link speeds on many of the major arterials in the state by relying on cell phone position data from mobile search queries. We want to anticipate this kind of new data, so as to allow CalVAD to grow and remain relevant in the future.