Cities’ crash data flows: SFPD, DPH and SFMTA describe TransBase linkage and High Injury Network

City agencies told the Government Audit & Oversight Committee on July 23 how they share traffic‑collision information to guide Vision Zero investments.

Deputy Chief Dan Perea (SFPD) described police collision response and investigations. SFPD classifies collisions (property damage, complaint of pain, severe injury, fatal) and dispatches traffic‑specialist motorcycle officers for diagramming. Severe injuries and fatalities trigger expanded investigation by the Traffic Collision Investigation Unit and coordinated notifications to SFMTA, Public Health and city leadership.

DPH officials outlined the TransBase system and a probabilistic linkage the department conducts between police crash reports and hospital trauma records at Zuckerberg San Francisco General Hospital. That linkage — the Traffic Injury Surveillance System (TISS) — identifies severe injuries not captured in police reports; DPH said roughly 28% of severe injuries appear only in hospital data. The linked police‑hospital dataset forms the basis of the city’s High Injury Network, which MTA uses to prioritize quick‑build engineering projects, signal retiming, crosswalk upgrades and other capital and operational countermeasures.

SFMTA staff explained the agency’s rapid‑response protocol for fatal collisions (site visit within roughly 24 hours), and how crashes feed a planned program of citywide quick‑build installations on high‑injury corridors. Agency engineers said many fatality sites already fall inside the High Injury Network and described how the city balances immediate maintenance fixes (lighting, markings) with longer‑term capital solutions (road diets, signal work) and enforcement/education strategies.

Committee members asked how rapidly agencies respond to severe injuries and requested additional breakdowns (for example, trends in hit‑and‑run involvement). Agencies committed to returning with more granular data and emphasized the ongoing interdepartmental data improvements — including work to replace outdated record systems and make reporting more timely and geospatially precise.

The committee filed (closed) the hearing record for item 3 after the presentations and public comment.