A blind spot is an area around a vehicle that the driver cannot see, either directly through the windows or by using the mirrors. Every vehicle has them, but large trucks and buses have much larger blind spots than passenger cars. FMCSA calls these areas around large trucks the No-Zones.
Blind spots contribute to lane-change crashes, turning collisions, backing incidents and struck-by injuries to pedestrians and workers on foot.
Where Are a Large Truck's Blind Spots?
According to FMCSA safety guidance, large trucks have four main No-Zones:
- Front: roughly the first 20 feet in front of the cab, where a low car or a pedestrian can be hidden below the driver's line of sight.
- Rear: roughly 30 feet behind the trailer. Trucks have no rear-view mirror, so a vehicle tailgating the trailer is invisible.
- Left side: along the driver's side, behind the cab door.
- Right side: the largest blind spot, extending along the passenger side and across more than one lane. Right turns and right lane changes are especially risky.
A useful rule shared with the public is that if a car driver cannot see the truck driver's face in the truck's side mirror, the truck driver cannot see the car.
Regulations and Equipment
Under 49 CFR 393.80, commercial motor vehicles generally must have two rear-vision mirrors, one at each side, positioned to give the driver a view of the highway to the rear along both sides. Many fleets add convex mirrors, hood mirrors, backup cameras, side-view camera systems and blind spot detection sensors to reduce what the driver cannot see. Drivers check mirrors as part of the pre-trip inspection and report defects on the driver vehicle inspection report.
How to Reduce Blind Spot Risk Step by Step
- Adjust mirrors before every trip. Set flat and convex mirrors so they cover the sides of the trailer and adjacent lanes.
- Scan constantly. Check mirrors every few seconds and before any lane change, turn or merge.
- Signal early. Give other drivers time to move out of the No-Zone.
- Make right turns carefully. Turn slowly, watch the right mirror throughout, and avoid swinging wide into the left lane.
- Get out and look before backing. Walk around the vehicle, use a spotter where possible, and back toward the driver's side when you can.
- Use technology as a supplement. Cameras and sensors help, but they do not replace mirror checks.
- Control yard traffic. Separate pedestrians from trucks at docks and yards with marked walkways and rules.
Common Mistakes to Avoid
- Driving with mirrors that are dirty, cracked or out of adjustment.
- Relying on cameras or sensors and skipping mirror checks.
- Backing without a walk-around or spotter.
- Workers walking behind or beside trucks without making eye contact with the driver.
How SMS360 Helps
SMS360's Vehicle Accident Register helps fleets record and review crashes, including lane-change, turning and backing incidents linked to blind spots. Reviewing these records over time helps identify drivers, routes or vehicles that need coaching, equipment upgrades or other corrective actions.
Frequently Asked Questions
What is the biggest blind spot on a truck?
The right side is usually the largest blind spot on a large truck. It can extend along the full length of the trailer and across more than one lane, which is why right turns and right lane changes require extra care.
How far behind a truck is the blind spot?
FMCSA guidance describes the rear No-Zone as about 30 feet behind the trailer. Vehicles following closely in that area cannot be seen by the truck driver and have little time to react if the truck stops suddenly.
Do backup cameras eliminate blind spots?
No. Backup and side cameras reduce blind spots but do not eliminate them, and they can be affected by dirt, glare and weather. Drivers should continue to use mirrors, walk-arounds and spotters as their main defenses.
