OOS Rate (Out-of-Service Rate)
The percentage of a carrier's roadside inspections that result in an out-of-service order, meaning the driver or vehicle is prohibited from operating until the violation is corrected. National average vehicle OOS rate is approximately 21%. CarrierOk provides both driver and vehicle OOS rates and flags carriers exceeding national averages.
Definition
The Out-of-Service (OOS) rate measures the percentage of a carrier's roadside inspections that result in an out-of-service order — a directive that prohibits the driver from driving or the vehicle from being operated until the cited violation is corrected. OOS rates are calculated separately for driver violations and vehicle violations. Common driver OOS violations include hours-of-service exceedances, suspended or invalid CDL, and failed alcohol/drug tests. Common vehicle OOS violations include brake system deficiencies, tire failures, and lighting/electrical issues. The national average driver OOS rate is approximately 6%, and the national average vehicle OOS rate is approximately 21%. Carriers with OOS rates significantly above these averages demonstrate systemic compliance failures — either their maintenance programs are inadequate (vehicle OOS), their driver management is poor (driver OOS), or both. OOS rates are a component of the ISS score calculation and correlate with BASIC percentiles in the Vehicle Maintenance and Driver Fitness categories. CarrierOk surfaces both driver and vehicle OOS data (inspections_driver_out_of_service, inspections_vehicle_out_of_service) and provides alert flags (oos_alert_driver, oos_alert_vehicle) when a carrier's rates exceed national thresholds.
Why It Matters
For Underwriters
A vehicle OOS rate above 30% indicates chronic maintenance neglect — these carriers produce more mechanical-failure claims, and their equipment condition is a liability in nuclear verdict depositions.
For Brokers
High OOS rates mean your carrier's trucks are getting pulled off the road at inspection stations, causing transit delays and potential load failures — check OOS rates alongside BASICs to assess operational reliability.
For Developers
Use oos_alert_driver and oos_alert_vehicle as boolean flags to gate carrier approval — these are pre-computed against national averages so you don't need to maintain threshold logic.
Key Values
| National Avg Driver OOS | ~6% |
| National Avg Vehicle OOS | ~21% |
| Common Driver OOS | HOS, CDL, drug/alcohol |
| Common Vehicle OOS | Brakes, tires, lights |
In the API
/v2/profileRelated Fields
inspections_driver_out_of_serviceinspections_vehicle_out_of_serviceoos_alert_driveroos_alert_vehicleinspections_totalFrequently Asked Questions
What is a good OOS rate for a trucking company?
A good OOS rate is below the national average. For vehicle inspections, the national average is approximately 21%, so anything below 15% is considered strong. For driver inspections, the national average is approximately 6%, so below 4% is good. Carriers with zero OOS on a meaningful number of inspections demonstrate excellent maintenance and driver management programs.
What happens when a truck is placed out of service?
When a vehicle receives an OOS order during a roadside inspection, it cannot be operated until the cited violation is repaired. The truck stays at the inspection site (or is towed to a repair facility) until a qualified mechanic fixes the issue and the vehicle passes re-inspection. This can cause hours or days of delay depending on the severity of the violation and the availability of repairs.
What is the difference between OOS rate and BASIC percentile?
OOS rate is a simple percentage — inspections resulting in OOS orders divided by total inspections. BASIC percentiles are peer-relative rankings that incorporate the severity and recency of individual violations, weighted by time. A carrier can have a moderate OOS rate but a high Vehicle Maintenance BASIC if their violations are recent and severe. Both metrics inform risk, but BASICs provide more nuanced insight.
Related Terms
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.
ISS Score (Inspection Selection System)
FMCSA's composite 1-100 algorithm for prioritizing carriers at roadside inspections. Higher scores mean higher inspection probability. The insurance industry widely uses ISS as a single-number risk indicator because it synthesizes multiple BASIC dimensions. CarrierOk serves ISS scores via the iss_score API field.
HOS (Hours of Service)
Federal regulations limiting commercial driver operating hours to prevent fatigue-related crashes. Key limits include 11 hours driving, 14 hours on-duty, and mandatory 30-minute breaks. HOS violations are one of the 7 BASIC categories tracked in CarrierOk's BASIC percentile data.
Safety Rating
A rating assigned by FMCSA after a compliance review: Satisfactory, Conditional, or Unsatisfactory. An Unsatisfactory rating can trigger an out-of-service order. However, most carriers have never been reviewed and carry no rating — absence of a rating does not indicate safety. CarrierOk includes safety rating status in carrier profiles.