Large commercial trucks have areas around them that cannot be seen as easily as the space surrounding a passenger vehicle.

Their size, cab position, trailer length, and reliance on mirrors can leave substantial areas beside, behind, and immediately in front of the truck outside the driver’s direct view.

FMCSA refers to these areas as blind spots or “No-Zones.”

A blind spot does not automatically explain why a truck collision occurred. Commercial drivers are expected to monitor surrounding traffic and account for limited visibility when changing lanes, turning, merging, or making other maneuvers. When a crash involves a vehicle that may have been outside the driver’s direct view, the investigation can focus on whether the driver used available mirrors and observations appropriately before moving the truck.

Blind Spots Extend Around Several Parts of a Large Truck

A semi-truck’s visibility problem is not confined to one small area beside the trailer. FMCSA explains that commercial vehicles can have significant blind spots on all four sides. Passenger vehicles can become difficult or impossible for the truck driver to see while traveling alongside, immediately behind, or close to the front of the truck.

That creates particular concern when traffic remains beside a truck for an extended period. A vehicle that was visible moments earlier can enter an area not adequately shown by the mirrors.

Truck drivers therefore need to maintain awareness of surrounding traffic over time rather than relying only on a single mirror check immediately before a maneuver. FMCSA advises commercial drivers to check mirrors regularly so they remain aware of vehicles entering their blind spots.

Lane Changes Can Turn a Visibility Gap Into a Collision

A Puyallup semi-truck accident attorney reviewing a sideswipe or lane-change collision may need to determine where the passenger vehicle was positioned before the truck began moving laterally.

FMCSA describes inadequate surveillance as a situation in which a commercial driver needs to look before completing a maneuver but either fails to look in the appropriate place or looks without detecting approaching traffic. Lane changes and turns are among the situations in which this problem can occur.

Commercial driver guidance calls for multiple mirror checks around a lane change: before changing lanes, after signaling, after beginning the movement, and again after completing it. Drivers are also instructed to remain aware that mirrors do not display every surrounding area.

After a crash, vehicle damage, lane markings, witness accounts, video, and available onboard information may help establish whether another vehicle was already occupying the lane when the truck began moving.

Right Turns Create a Different Blind-Spot Conflict

Truck turns can create a particularly dangerous situation on the passenger side.

Large trucks often require more room to turn than passenger vehicles. FMCSA warns that trucks making right turns may initially move left to create enough space to complete the maneuver. Other road users are advised not to enter the opening between a turning truck and the curb.

From the truck driver’s perspective, however, the wide turn does not remove the obligation to monitor the surrounding area. A passenger vehicle, cyclist, or pedestrian near the truck’s right side can become difficult to see as the truck and trailer change angles through the turn.

An investigation involving a right-turn collision may therefore consider the truck’s approach, turn signal, mirror use, path through the intersection, and the location of the other road user before contact occurred.

The issue is not merely that the truck had a blind spot. The more specific question is whether the driver accounted for that known visibility limitation before and during the turn.

Backing Creates a Visibility Problem Directly Behind the Truck

The area behind a long commercial vehicle presents another challenge because the driver cannot simply turn and obtain the same rearward view available in a smaller vehicle.

FMCSA warns pedestrians that truck drivers cannot see directly behind their vehicles while backing. Commercial driving materials also emphasize frequent mirror use during tight maneuvers.

Backing accidents may happen in loading areas, parking lots, delivery locations, construction environments, or other spaces where vehicles and people move close to a truck.

When such a collision occurs, the investigation can examine more than the final position of the truck. Questions may include whether mirrors were properly positioned, whether the driver checked the area before reversing, whether another person was directing the maneuver, and whether cameras or proximity-warning equipment were installed.

Mirrors Reduce Blind Spots but Do Not Eliminate Them

Commercial truck mirrors are designed to increase what drivers can see, but they do not create complete visibility around the vehicle.

FMCSA research notes that large trucks have substantial areas obscured from both direct and indirect driver vision. Convex mirrors can increase the field of view compared with standard planar mirrors, but they can also distort the appearance of objects.

Mirror adjustment consequently matters. Commercial driving guidance instructs drivers to check mirror adjustment before a trip and use visible portions of the vehicle as reference points for judging the position of objects shown in the mirrors.

After a collision, investigators may examine whether mirrors were damaged by the impact, how they were positioned, and what areas they would have shown before the crash.

A driver saying another vehicle was “in my blind spot” does not by itself resolve the question of fault. Blind spots are a known characteristic of large trucks that drivers are trained to manage.

Passenger-Vehicle Drivers Also Benefit From Understanding No-Zones

Preventing blind-spot collisions requires awareness from everyone sharing the road.

FMCSA advises passenger-vehicle drivers not to linger beside large trucks. One practical guideline is that if a motorist cannot see the truck driver’s face in the truck’s mirror, the truck driver may not be able to see that vehicle.

Drivers can also avoid attempting to pass on the right while a truck is making a wide right turn and can move through side blind spots without remaining alongside unnecessarily.

These precautions do not automatically transfer legal responsibility for a collision to the smaller vehicle. They are safety practices designed to reduce the opportunity for a visibility conflict to develop.

A Blind Spot Is the Beginning of the Investigation, Not the Conclusion

When a truck driver claims another vehicle was hard to see, it raises questions. An investigation should look at where both vehicles were, when the truck began to move, if signals were used, how mirrors were set, what the driver could see, and if any video or witness accounts support either side.

Large trucks have significant blind spots. The FMCSA reminds drivers to check these areas often, as smaller vehicles can easily disappear from view.

After a crash, the key question is not just about the blind spot. It’s whether the truck driver and other road users acted appropriately given this limitation and what the evidence shows about what happened before the crash.