Data & methodology

Source

Every incident on CrashGuide comes from the California Highway Patrol's public Computer-Aided Dispatch (CAD) feed — the same live incident information CHP publishes for all of its communications centers statewide. We poll the feed roughly every 75 seconds, identify ourselves to CHP's servers, and archive each incident's full lifecycle: when it was first reported, every dispatch log update, and when it cleared. CHP does not archive this data; once an incident scrolls off the live feed it is gone from public view. CrashGuide preserves it.

Enrichment

We resolve each incident's county and city with the U.S. Census Bureau's geocoder, parse roadway and cross-street from the dispatch location string, and identify the likely reporting agency (a CHP Area office for most freeway incidents; a local police department for many city-street incidents). When coordinates cannot be confirmed at high confidence, maps show an approximate area rather than a precise pin.

Known limitations

Dispatch data is preliminary and unverified — initial reports are often revised as an incident develops, and some never receive updates. Coverage is strongest on freeways and state highways, which CHP patrols; many city-street collisions are handled by local police departments and never appear in CHP's feed. Severity classifications reflect the dispatch type code, not medical outcomes. Nothing on this site is an official record; official collision reports are available only from the investigating agency.

What we never publish

The CAD feed contains no names and no personal identifying information, and we never add any from any other source. No person is identified on this website, ever.