What does CMF < 1 indicate?

• A. Increase in crashes.
• B. No change in crashes.
• C. Reduction in crashes.
• D. It depends on the countermeasure.

Answer: (C)

Crash Modification Factor shows how a safety countermeasure changes crash frequency by comparing crashes with the countermeasure to crashes without it. A CMF less than one means there are fewer crashes after implementing the countermeasure than before, signaling a reduction. For example, if crashes drop from 100 to 70, the CMF is 0.70, reflecting a 30% reduction. A CMF equal to one means no change, and a CMF greater than one means more crashes after the countermeasure. The idea that it depends on the countermeasure isn’t needed here—the value itself indicates a reduction when it’s below one.