If you've ever looked up a trucking company's safety record, you've seen the term "out-of-service rate." But what does out-of-service actually mean, and why does it matter? Here's the complete explanation.
What Is an Out-of-Service Violation?
An out-of-service (OOS) violation occurs when a federal or state inspector determines during a roadside inspection that a commercial motor vehicle or driver poses an imminent safety hazard. The vehicle or driver is immediately prohibited from operating until the violation is corrected.
Out-of-service violations are the most serious outcome of a roadside inspection. They indicate a safety problem severe enough that an inspector determined the truck or driver was too dangerous to continue operating on public roads.
Vehicle OOS vs. Driver OOS
There are two types of out-of-service violations tracked by the FMCSA:
What Is an OOS Rate?
The out-of-service rate is the percentage of a carrier's inspections that result in an OOS violation. It's calculated separately for vehicle and driver violations:
OOS Rate = (Inspections with OOS Violations / Total Inspections) × 100
For example, if a carrier had 100 inspections and 25 resulted in vehicle OOS violations, their vehicle OOS rate would be 25%.
National Average OOS Rates
The FMCSA publishes national average OOS rates that serve as benchmarks:
| Metric | National Average | What It Means |
|---|---|---|
| Vehicle OOS Rate | 23.2% | About 1 in 4 inspections finds a vehicle unsafe to operate |
| Driver OOS Rate | 6.4% | About 1 in 16 inspections finds a driver unfit to operate |
Carriers with OOS rates significantly above these averages have worse-than-typical safety records. CarrierRecord uses OOS rates as a major component of our safety grading system — vehicle OOS rate accounts for up to 30 of 100 possible points.
Why OOS Rates Matter
OOS rates are one of the most reliable indicators of a carrier's safety culture because they reflect the actual condition of equipment and drivers at the point of inspection. Unlike self-reported data, OOS violations are documented by trained inspectors under standardized criteria.
- For shippers and brokers: A high OOS rate signals that a carrier may not maintain its fleet properly, increasing the risk of delays, breakdowns, and accidents
- For the public: OOS rates reveal which trucking companies are putting unsafe vehicles and drivers on the road
- For legal cases: A carrier's OOS history can establish a pattern of negligent maintenance in personal injury litigation
Check Any Carrier's OOS Rate
Every carrier profile on CarrierRecord shows vehicle and driver OOS rates compared to the national average.
What Triggers an OOS Violation?
The FMCSA maintains specific out-of-service criteria that inspectors follow. These are published in the North American Standard Out-of-Service Criteria handbook. The most common triggers include:
Vehicle OOS (Most Common Causes)
- Brake defects — The #1 cause of vehicle OOS violations. Includes worn brake linings, air leaks, out-of-adjustment brakes, and inoperative brake components
- Tire/wheel issues — Bald tires, flat tires, cracked rims, loose lug nuts
- Lighting — Inoperative headlamps, taillights, turn signals, or clearance lights
- Frame/body defects — Cracked frames, missing mud flaps, damaged fuel tanks
- Cargo securement — Improperly secured loads that could shift or fall
Driver OOS (Most Common Causes)
- Hours-of-service violations — Driving beyond the 11-hour driving limit or 14-hour duty window
- Invalid CDL — Expired, suspended, or wrong-class commercial driver's license
- Medical certificate — Expired or missing DOT medical examination certificate
- Record of duty status — Falsified or missing log books/ELD records
- Alcohol/drugs — Positive test or evidence of impairment
How CarrierRecord Uses OOS Data
CarrierRecord's safety grading system weighs both vehicle and driver OOS rates when calculating a carrier's overall safety grade. The vehicle OOS rate contributes up to 30 points and the driver OOS rate up to 20 points of the 100-point scale (lower scores are better). Carriers are also ranked against others in their state using percentile comparisons based on OOS rates.
You can look up any carrier's full safety profile by searching their name or DOT number on CarrierRecord. Every profile includes OOS rates compared to the national average, inspection history, crash records, and a letter safety grade.
Related Reading
- FMCSA Inspection Levels Explained — What happens at each of the six roadside inspection levels
- What Is a CSA Score? — How FMCSA's Safety Measurement System uses OOS data
- What to Do After a Trucking Accident — How OOS history can be relevant after an accident
- What Is a DOT Safety Rating? — The difference between safety ratings, CSA scores, and letter grades