SMS (Safety Measurement System)
FMCSA's quantitative system for measuring motor carrier safety performance using inspection, crash, and investigation data. SMS produces the BASIC percentile scores that underpin the CSA enforcement program. CarrierOk computes all 7 BASIC percentiles from SMS source data and updates more frequently than FMCSA's monthly cycle.
Definition
The Safety Measurement System (SMS) is FMCSA's methodology for quantifying motor carrier safety performance. SMS ingests data from three primary sources: roadside inspections (conducted by state and federal law enforcement), crash reports (state-reported crashes meeting FMCSA severity thresholds), and compliance investigations. From this data, SMS computes BASIC percentile scores across seven categories by comparing each carrier's violation rates, severity, and recency against a peer group of carriers with similar inspection exposure. The SMS methodology applies time-weighting — more recent violations count more heavily than older ones — and severity-weighting — certain violations (like driving under the influence) receive higher severity weights than minor infractions (like a missing reflector). SMS data is updated monthly by FMCSA, typically during the last week of each month, using a 24-month rolling window. The system requires a minimum number of inspections before producing percentiles — carriers with insufficient inspection history will not have BASIC scores. SMS is the backbone of FMCSA's CSA program and the source of the BASIC percentile data that drives most carrier safety assessments in insurance and brokerage. CarrierOk processes SMS source data and computes all 7 BASIC percentiles (including the 2 FMCSA withholds from public view), making the complete safety picture available via a single API call.
Why It Matters
For Underwriters
SMS is where your BASIC percentile data originates — understanding that it uses time-weighted, severity-weighted, peer-relative methodology helps you interpret the scores correctly and explain them to agents and policyholders.
For Brokers
SMS data reflects actual roadside enforcement encounters, not self-reported information — a carrier can claim a perfect safety record, but their SMS profile shows what inspectors actually found.
For Developers
SMS updates monthly with a 24-month rolling window — build your caching and refresh logic around this cadence. CarrierOk processes SMS updates same-day, so polling our API monthly captures the full FMCSA update cycle.
In the API
/v2/profileRelated Fields
basic_percentile_unsafe_drivingbasic_percentile_hours_of_servicebasic_percentile_vehicle_maintenancebasic_percentile_controlled_substancebasic_percentile_driver_fitnessbasic_percentile_hazardous_materialsbasic_percentile_crash_indicatorbasic_measure_unsafe_drivingbasic_measure_hours_of_servicebasic_measure_vehicle_maintenanceFrequently Asked Questions
What is the Safety Measurement System?
SMS is FMCSA's system for quantifying motor carrier safety using data from roadside inspections, crash reports, and investigations. It produces BASIC percentile scores across seven safety categories by comparing each carrier against peers with similar operations. SMS uses time-weighting (recent events count more) and severity-weighting (serious violations count more) over a 24-month rolling window.
How often is SMS data updated?
FMCSA updates SMS data monthly, typically during the last week of each month. Each update recalculates BASIC percentiles using the most recent 24 months of inspection and crash data. CarrierOk processes these updates and makes them available via API the same day. Between monthly updates, individual inspection records may post to FMCSA's systems but won't be reflected in BASIC percentiles until the next monthly recalculation.
What is the difference between SMS and CSA?
SMS is the measurement system — it's the methodology and data processing that produces BASIC percentile scores. CSA is the enforcement program — it uses SMS data to identify high-risk carriers and take intervention actions (warning letters, investigations, compliance reviews). Think of SMS as the scorecard and CSA as the action plan. Together, they form FMCSA's primary framework for carrier safety oversight.
Related Terms
CSA (Compliance, Safety, Accountability)
FMCSA's enforcement and compliance program that uses the Safety Measurement System to identify and prioritize high-risk motor carriers for intervention. CSA drives BASIC percentile scores, warning letters, and compliance reviews. CarrierOk provides all 7 BASIC percentiles, alert flags, and historical trend data via API.
BASIC Percentile
A 0-100 peer-relative safety score across seven FMCSA categories: Unsafe Driving, HOS, Vehicle Maintenance, Controlled Substances, Driver Fitness, Hazmat, and Crash Indicator. Higher is worse. CarrierOk computes all 7 BASICs including the two FMCSA withholds from public view.
FMCSA (Federal Motor Carrier Safety Administration)
The federal agency within the U.S. Department of Transportation that regulates the trucking and bus industries. FMCSA issues operating authority, sets safety standards, and maintains the databases — SAFER, SMS, MCMIS, L&I — that CarrierOk indexes four times daily to power its carrier intelligence platform.
SAFER (Safety and Fitness Electronic Records)
FMCSA's public-facing website for looking up motor carrier safety information, including operating status, authority, and limited inspection data. SAFER does not compute BASIC percentiles, does not serve ISS scores, and updates less frequently. CarrierOk replaces manual SAFER lookups with a comprehensive, API-accessible carrier intelligence platform.