A 1995 North American survey of traffic management centers using ramp metering, identified reductions of 15 to 50 percent in freeway crashes.

A survey of traffic management centers using ramp metering reported that accidents on freeway systems under freeway management were reduced between 15 and 50 percent. While some other freeway improvements were implemented during the study periods, the combination of geometric, vehicle, and operational procedures resulted in significant reduction of accident rate.