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. These dates are estimates and are
subject to change; if there are problems with the validation, the process could
take longer than expected.
To understand more about the BASICS, review the SMS factsheet and briefings on the
Compliance, Safety, Accountability Website.
For even more detail, review the
SMS Methodology document. The document outlines which values are assigned
for each violation and how they are weighted in Appendix A, starting on page A-4
in the
SMS Methodology document.
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