What is a High-Injury Network (HIN)? How to Build One for Your Community

Every year, roughly 40,000 people die on U.S. roads. But these fatalities and serious injuries don’t happen randomly—they cluster on a small fraction of the road network. A High-Injury Network (HIN) maps exactly where those concentrations occur, giving transportation agencies the data they need to direct limited safety dollars where they’ll save the most lives.

If your community is pursuing a Safe Streets for All (SS4A) grant or developing a safety action plan, building a HIN is likely one of your first requirements. This guide explains what a HIN is, why it matters, and the step-by-step process for creating one.

What is a High-Injury Network?

A High-Injury Network is a map-based analysis that identifies the roads and intersections with the highest concentration of traffic fatalities and serious injuries. Rather than treating every road equally, a HIN reveals the small percentage of streets that account for a disproportionate share of severe crashes.

HINs are increasingly required in federal grant applications, local Vision Zero plans, and state safety programs. USDOT specifically references High-Injury Networks in SS4A grant guidance as a recommended analytical tool for Safety Action Plans.

Why Build a High-Injury Network?

• Prioritize limited funding — Focus safety investments on corridors and intersections where they’ll have the greatest impact on reducing fatalities and serious injuries
• Strengthen grant applications — SS4A and HSIP grants expect data-driven prioritization. A HIN demonstrates analytical rigor to reviewers
• Build public support — Visual maps showing crash concentrations communicate urgency to elected officials, residents, and stakeholders far more effectively than tables of numbers
• Meet federal requirements — The Federal Highway Administration (FHWA) encourages systemic safety analysis, and HINs align with the Safe System approach promoted in the National Roadway Safety Strategy
• Guide equitable investment — HINs can be overlaid with equity data to ensure historically underserved communities receive proportionate safety improvements

How to Build a High-Injury Network: 6 Steps

HIN Best Practices

Use Severity Weighting

Raw crash counts treat a fender-bender the same as a fatality. Severity-weighted scoring (like EPDO) ensures your HIN prioritizes the most dangerous locations, not just the busiest ones.

Include Vulnerable Road Users

Pedestrian and cyclist crashes are often underreported in crash databases but represent some of the most severe outcomes. Consider creating separate HIN layers for pedestrians, cyclists, and motorists to reveal mode-specific risk patterns.

Update Regularly

A HIN is not a one-time exercise. As crash patterns shift due to new development, road modifications, or changing travel behavior, your HIN should be refreshed annually or when new data becomes available.

Overlay with Equity Data

USDOT and many state DOTs now require or encourage equity analysis alongside safety analysis. Overlay your HIN with census tract data on income, race, vehicle ownership, and transit access to identify whether high-injury corridors disproportionately affect disadvantaged communities.

Common Challenges

• Data quality issues — Missing coordinates, inconsistent severity coding, and underreported pedestrian/cyclist crashes all affect HIN accuracy. Budget time for data cleaning.
• Choosing the right threshold — Too broad and everything is “high injury.” Too narrow and you miss important corridors. Test multiple thresholds and validate against local knowledge.
• Segment length sensitivity — Very short segments can appear disproportionately dangerous due to a single crash cluster. Normalize by segment length or use consistent segmentation.
• Communicating results — Technical maps don’t always resonate with decision-makers. Use interactive dashboards and clear visualizations that tell a story about where people are getting hurt.

HINs and SS4A Grant Applications

If you’re applying for an SS4A Action Plan Grant, building a HIN is one of the most impactful analyses you can include. USDOT reviewers look for evidence that applicants understand where their worst safety problems are concentrated and have a data-driven strategy for addressing them.

Your HIN can directly inform multiple elements of a Safety Action Plan:

1. Comprehensive safety analysis — The HIN itself serves as the foundation of your crash analysis
2. Project prioritization — HIN corridors become candidate locations for safety countermeasures
3. Equity considerations — Overlaying the HIN with equity data satisfies the equity analysis requirement
4. Implementation strategy — The HIN guides where to invest implementation grant funding

Explore the SS4A Award Map to see which communities have received funding and the types of safety challenges they’re addressing.