How are the Safety Measurement System (SMS) percentile ranks calculated?

SMS evaluates the safety of individual motor carriers by considering all safety-based roadside inspection violations, not just out-of service violations, as well as state-reported crashes, using 24 months of performance data. SMS assesses motor carriers’ safety performance in each of the seven Behavior Analysis and Safety Improvement Categories (BASICs): Unsafe Driving, Hours-of-Service Compliance, Driver Fitness, Controlled Substances/Alcohol, Vehicle Maintenance, Hazardous Materials Compliance, and Crash Indicator.

SMS calculates a measure for each BASIC by combining the time- and severity-weighted violations/crashes (more recent violations are weighted more heavily), normalized by exposure, which is a statistical calculation that allows SMS to make a fair comparison between carriers with different levels of activity (e.g., a hybrid of the number of Power Units per Vehicle Miles Traveled or the number of relevant inspections). The SMS converts each carrier’s BASIC measures into percentiles based on rank relative to carriers with similar safety event groupings (i.e., number of relevant inspections, number of inspections with violations, or number of crashes).

The SMS is updated monthly, taking a snapshot of data on the third or last Friday of each month, and takes approximately 10 business days to process and validate the data before it is uploaded on the website.