High injury networks (HINs) include stretches of roadways where
the highest concentrations of collisions occur on the
transportation network. The HIN is intended to show where fatal
and serious collisions are occurring in the region. The HIN,
however, is not an assessment of whether a street or location is
dangerous. Rather, the 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
Determining geographic areas where crashes are concentrated,
and the causes of these crashes, so that efforts can be
focused on the most challenging areas and crash factors.
Strengthening collaboration to focus street improvements and
education campaigns (e.g., Go Human) along the HIN.
Prioritizing investments within these areas to reduce
Through case studies from the Cities of San Francisco and Los
Angeles, Oregon Metro, and the Portland Bureau of Transportation,
SCAG developed a methodology to map a regional HIN. To identify
where most of the collisions are occurring, SCAG created an HIN
at a regional scale utilizing a five-year dataset from U.C.
Berkeley’s Transportation Injury
Mapping System (TIMS 2010-2014). This interactive story map
identifies the high injury network for the SCAG region
by modes. Although SCAG’s Regional Safety Existing Conditions
Report provides crash rates at the regional and county levels,
the HIN is not normalized by vehicle miles traveled (VMT) or by
population, as would be done to create crash rates. The HIN crash
scores are purposefully not normalized by VMT or population
because the intent was to identify corridors with the highest
concentrations of serious injury and fatal crashes, compared to
the rest of the county, no matter the number of VMT or
population. This intent is tied directly to achieving our Towards
Zero Deaths-related safety targets and to help local
jurisdictions focus on improvements where they are most needed.
SCAG has identified cities in our region that are a part of
SCAG’s high injury network. SCAG aims to work closely with these
cities to identify safety concerns, reduce fatalities, and
serious injuries, and in turn achieve our regions safety targets.
While developing HIN at a regional level helps in identifying
cities in the SCAG region with safety concerns, it is recommended
that cities develop an HIN at the city level to identify
concentrations of collisions. Details on High Injury Network
mapping are provided in the Transportation Safety and Security
Technical report (linked above) and at Connect SoCal.