Safety & service
Understanding Tail Swing in a Delivery Truck
A delivery truck can clear a parked car with its front end and still strike it with the rear corner. The part of the body extending behind the rear axle moves through a different path when the driver turns. This outward movement, known as tail swing, is easy to overlook when attention is fixed on the curb or the road ahead. This Sigma Continental explanation shows why departures from tight spaces require attention to the entire truck, including areas moving away from the intended turn.
Distinguish the rear corner from the rear wheels
During a forward turn, the rear overhang can initially swing toward the side opposite the turn. A truck turning right may therefore move its left rear corner toward a nearby object. Tail swing is different from offtracking, in which the rear wheels follow a path inside the front wheels. Both movements affect the clearance needed around the vehicle. Commercial driver training addresses monitoring rear overhang during turns. 1
There is no single tail-swing distance for all delivery trucks. Rear overhang, wheelbase, steering angle, and vehicle configuration matter. A driver switching to a longer body should not assume the familiar truck’s reference points still apply. Learn the actual vehicle’s dimensions and turning behavior during approved training in a controlled area.
Plan room on both sides before turning
Before pulling away from a curb, loading area, or parking space, consider what is close to the rear corners. A bollard, signpost, another vehicle, or a person standing beside the truck can be outside the front’s path but inside the rear body’s sweep. Check the complete departure path before applying a steering input.
FMCSA reminds commercial drivers to allow adequate room and time for turns and to account for blind spots. 2 Where the layout allows it, establishing appropriate clearance before turning may reduce the risk. That does not mean swinging into another lane or crossing a sidewalk. If the space is insufficient for the whole vehicle, stop and choose a different approved maneuver.
Monitor the sweep throughout the movement
Use both mirrors to follow the truck’s sides and rear corners while continuing to observe the path ahead. Move slowly enough that an uncertain clearance can be addressed before contact occurs. Avoid staring at only the inside rear wheel: the outside rear corner may be approaching a separate hazard at the same time.
If a mirror view cannot establish clearance, stop, secure the vehicle, and get out to look. Use an appropriately trained spotter when available, with clear communication and a safe position. Do not continue because the front bumper has already cleared the obstacle. The relevant question is whether every part of the truck can complete the turn without entering another person’s or object’s space.
Recheck after changes to the truck or location
A different vehicle body, rear-mounted equipment, or changes in the parking area can alter the clearances a driver needs to manage. Report unfamiliar dimensions and ask for orientation before operating replacement equipment. At a familiar stop, a newly placed dumpster or parked van may remove space that was available yesterday.
Drivers moving between delivery vehicles should practice identifying these different movement paths before entering confined locations. Consider a left turn away from a loading entrance with a wall close to the truck’s right rear. Looking only into the left turn misses the initial movement toward that wall. Planning the complete path, observing both sides, and stopping when uncertain keeps a routine departure from becoming a preventable contact incident.
Sources and further reading
Review current guidance and follow the training and procedures provided for your role.
- Original Safety Articles collection
- California Department of Motor Vehicles — California Commercial Driver Handbook
- Federal Motor Carrier Safety Administration — Tips for Truck and Bus Drivers
