Substantive safety focuses on which metric?

• A. Historical collision data
• B. Traffic volumes
• C. Expected crashes based on long-term data trends
• D. Roadway characteristics

Answer: (C)

Substantive safety is about the actual risk of crashes as a measurable outcome, estimated from long-term data trends. By looking at extended histories of crashes and how they relate to exposure over time, you get an expected number of crashes that reflects underlying risk rather than just counting past events in a single year. This approach lets you gauge safety performance and predict future risk to guide improvements.

Historical collision data describe what happened in the past, and traffic volumes relate to exposure, while roadway characteristics describe the environment. But the metric used to assess substantive safety is the expected crashes based on long-term data trends, which combines past crash information with how exposure and conditions evolve over time to project future crashes.