U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Difference between Nominal and Substantive safety. Nominal safety: a design feature or roadway either meets minimum criteria or it does not. Substantive safety is the actual long term or expected safety performance of a roadway; determined by its crash experience measured over a long enough time period to provide a high level of confidence that the observed crash experience is a true representation of the expected safety characteristics of that location or highway.