Ergonomic considerations in trucking delivery operations: An evaluation of hand trucks and ramps

Truck drivers who perform customer deliveries routinely use ramps and two-wheeled hand trucks to unload product from the trailer. During this activity, drivers exert high hand forces when maneuvering the hand truck down the ramp and are exposed to an elevated risk of slips and falls due to increased frictional requirements at the shoe-ramp interface. This study was performed to evaluate the effects of hand truck design, hand truck load, and ramp characteristics on musculoskeletal stresses experienced by drivers when going down ramps. Hand forces and working postures were recorded with motion analysis hardware and software while an experienced driver performed ramp delivery operations using various combinations of hand truck (three types, two braked, one unbraked), product load (three levels, 37, 78, 151 kg), and ramp (four types, three planar surfaces with slopes ranging between 19.1 degrees and 21.6 degrees and one stepped surface with a slope of 19.2 degrees) in a full-factorial design, Hand forces were reduced by more than 60% when using brake-equipped hand trucks. Brakes also reduced the frictional requirements at the shoe-ramp interface. Frictional requirements were reduced with longer ramps and were lowest for the long ramp with the stepped surface, It was concluded that brakes are a very desirable feature for hand trucks used in ramp delivery operations, A strong conclusion regarding ramp design was not reached. Although the stepped-surface ramp required the lowest friction, the noncontinuous design of its walking surface may create a tripping hazard, and additional study is needed.