FHWA-funded searchable database of Crash Modification Factors with star-quality ratings.
Why: the citable source for “this countermeasure reduces crashes by X%”; star rating + applicability (crash type, severity, context) decide defensibility.
When:
- countermeasure selection
- safety B/C
- calming effectiveness claims
Example questions:
- CMF for adding a raised median on 4-lane urban arterial, for KABC injury crashes?
- Is the study context comparable to mine?
Rule
Never quote a CMF without its star rating, crash type, and base condition.
Free companions
Trainings & Resources — free training videos, the 2-page CMF Quick Start Guide, the “CMFs in Practice” 5-guide series, and guidance on applying multiple CMFs (the part everyone gets wrong). Note the Clearinghouse now lives at cmfclearinghouse.fhwa.dot.gov — the old .org link redirects.
Related: Countermeasure Selection and CMFs · Highway Safety Manual (HSM)