A roadside inspection can turn up a violation and let the truck keep moving, or it can put the truck or driver out of service right there. Those are two very different real outcomes, and most discussion of FMCSA compliance talks about violation counts without separating them. So we pulled the real Safety Measurement System (SMS) input data -- over 5.8 million roadside inspections -- and looked at both: how often each BASIC category actually gets cited, and how often that citation is serious enough to be an out-of-service order.
| BASIC category | Real violation volume | OOS rate |
|---|---|---|
| Vh Maint | 1,914,895 | 14.78% |
| Unsafe | 609,590 | not in this extract |
| Fatigued | 443,495 | not in this extract |
| Dr Fitness | 335,764 | 5.88% |
| HM | 29,960 | 0.24% |
| Subt Alcohol | 12,993 | not in this extract |
Volume and out-of-service rate tell different stories
Volume and severity don’t move together: Vehicle Maintenance drew 1,914,895 real violations at a 14.78% out-of-service rate, while Driver Fitness drew far fewer (335,764) but a lower 5.88% rate — more citations doesn’t always mean a more severe one.
Vehicle Maintenance violations dominate the real count -- by a wide margin over every other category in the table above. That alone would suggest maintenance is where enforcement attention concentrates. What the out-of-service rate adds is a second, sharper signal: a real, substantial share of those maintenance violations are severe enough to be an immediate out-of-service order, not just a citation the driver keeps moving with. Driver Fitness violations run at a fraction of the volume but still carry a real, meaningful out-of-service rate of their own. Hazardous Materials violations sit at the opposite end on both measures -- the lowest real volume of the six categories, and the lowest real out-of-service rate, meaning a hazmat violation is comparatively rare at roadside and, when it happens, comparatively less likely to stop the truck on the spot (it still carries real separate regulatory consequences that don’t show up in an out-of-service rate).
Why Unsafe Driving and Fatigued Driving don’t show an out-of-service rate here
Not every BASIC category in this real extract has a recorded out-of-service rate -- Unsafe Driving, Hours-of-Service/Fatigued Driving, and Controlled Substances/Alcohol show real violation volume but no out-of-service figure in this specific dataset. Rather than estimate or backfill a number we can’t verify, the table shows exactly what the source data supports for each category and marks the rest honestly as not captured in this extract -- the same discipline every dataset behind CertQuestUSA’s Risk Index follows.
Where this data comes from
Every figure on this page is pulled live from the same real US FMCSA Safety Measurement System (SMS) input data (2023-01-01 through 2026-12-31) that powers CertQuestUSA’s public Risk Index. Full disclosed methodology, every BASIC category, and the EPA/OSHA/CMS/BLS datasets alongside it: see /risk-index.