Forensic Engineering Assessment of Safety for Stand Up Forklifts

Richard M. Ziernicki, PhD, PE (NAFE 308F) | Ben T. Railsback, P.E. (NAFE 308F)


Forklifts operated from a stand up position rather than a seated position offer a significant advantage to increase warehouse capacity. Stand up lift trucks can be operated in warehouse aisles as narrow as 8 feet.

In contrast, traditional sit down lift trucks typically require aisles approximately 11 feet wide. Aisle width reduction can increase warehouse capacity approximately 20 to 25 percent. However, a significant hazard exists with the use of stand up lift trucks that does not exist with sit down lift trucks: the hazard of a horizontal rack beam entering the operator compartment and crushing the operator.

Sit down lift trucks are equipped with a roll over protective structure typically comprised of a canopy supported by four vertical posts. Stand up lift trucks are typically equipped with a overhead guard to protect the operator from falling objects, however the rear of the canopy is not typically supported by posts. The overhead guard design leaves the rear of the operator compartment open, and horizontal rack beams can intrude into the operator compartment, crushing the operator between the rack and the lift truck.

Hundreds of serious accidents have resulted from this hazard and over a dozen operators have sustained fatal injuries.

Another significant hazard related to stand up lift trucks is the hazard of a lower limb injury or foot crush due to the opening across the rear of the operator compartment. Numerous injuries have occurred to the lower limbs of stand up lift truck operators due to the close proximity of the operator’s lower limbs to the exterior of the lift truck, and the confined areas that stand up lift trucks operate in. The operator’s foot or leg can become pinned between the moving lift truck and a fixed object such as a rack system, column, or another lift truck.

The accident database compiled by one of the stand up forklift manufacturers indicates that the manufacturer’s stand up lift trucks have been involved in over 3,000 incidents/accidents in the last thirty years. Over 500 accidents involving lower limb injury/foot crush have occurred. Both foot crush injuries and horizontal intrusion injuries share a common theme: the operator becomes injured while the lift truck is traveling in a forks trailing manner (traveling with the forks or load end following the truck.)

Published By


Journal of the National Academy of Forensic Engineers, June, 2008
2008