Regional High Injury Network


High injury networks (HINs) include stretches of roadways where the highest concentrations of collisions occur on the transportation network. An HIN is intended to show where fatal and serious collisions are occurring in the region. An HIN, however, is not an assessment of whether a street or location is dangerous. Rather, an HIN suggests which corridors within a transportation network carry a higher risk of injury. When developing an HIN, jurisdictions typically want to identify a subset of the network where the most collisions are occurring (>50%). Developing an HIN can prove helpful for a variety of reasons, including:

  • Identifying areas of need;
  • Providing agency staff with more information on where they can focus limited resources;
  • Providing opportunities to understand how communities of concern or disadvantaged communities are impacted by higher rates of collision and serious injury; and
  • Assisting with building greater public and political support.

In 2018, SCAG developed its first regional HIN. In developing the HIN, SCAG reviewed HIN methodologies for a variety of jurisdictions including Los Angeles, San Francisco, Portland, and Portland Metro. SCAG borrowed elements from their approaches to develop one that could work for the entire region. To learn more about where injuries are occurring throughout Southern California, please view this supplemental web resource developed in conjunction with SCAG’s regional HIN.

In 2020, SCAG convened a statewide working group to develop recommendations for High Injury Network (HIN) statewide guidance. The group was formed from members of the Strategic Highway Safety Plan (SHSP) Bicycle and Pedestrian Challenge Teams. This work was motivated by recommendations from California’s Zero Traffic Fatalities Task Force and culminated in the development of this report, which includes a review of California HINs developed at the city, county, and metropolitan planning organization levels of government, and provides details on which components were included in each HIN and how they were created. Based on HINs reviewed, the report presents recommendations for statewide guidance on a definition and methodology for HINs. In September 2021, the report was shared with Caltrans and staff are currently reviewing the report and considering how the recommendations can be institutionalized into statewide guidance.