University of California Institute of Transportation Studies

There are two official sources of data on traffic incidents in California: 1) the Statewide Integrated Traffic Records System (SWITRS), intended to include incidents leading to injury or death; and 2) the California Highway Patrol (CHP) data on Caltrans’ Performance Measurement System, PeMS. Traffic safety researchers rely heavily on the post-processed SWITRS database, which provides only some crucial information about crashes. In 2015, the Road Ecology Center at UC Davis developed a third method to collect all incident data that appear on the CHP real-time incident-reporting web-site (https://cad.chp.ca.gov/). These data are assembled into a database called CHIPS, for California Highway Incident Processing System. Analyses indicate that the number of incidents recorded in a given period are similar in CHIPS and SWITRS but lower in PeMS. Also, many SWITRS records (e.g., 36% in 2018), but no CHIPS records, lack or have inaccurate location information on incidents. Through case studies, the research group examined three ways that CHIPS can be used to support data and policy analysis. This report proposes future pathways for creating a more integrated system for collecting and analyzing crashes.