A checklist for evaluating cab design of construction equipment.

Awkward postures during the oper­ ation of heavy construction equipment are a consequence of improper cab de­ sign and work procedures. Poor visi­ bility of the task, limited room in the cab, excessive forces required to operate levers/pedals, and improper seat designs are some of the characteristics of a poorly designed cab. If not controlled, awkward posture of any body part can result in in­ creased risk of fatigue, pain, or injury. Exposure to awkward postures, either repetitively or for prolonged periods, can lead to a variety of musculoskeletal disorders. Laboratory studies have shown that non-neutral trunk postures (i.e., flexion, lateral bending, and/or twisting) caused increased levels of muscle fatigue and intervertebral disc pressure in the lower back.(1) Epidemiological studies have shown that flexion, lateral bending, and twisting of the trunk are factors in the de­ velopment of low back pain.(2,3) Spinal disc compression can increase substan­ tially when the trunk changes from a neutral to a flexed posture.(4) Further­ more, prolonged sitting can also re­ sult in an increased risk of low back pain.(5) Laboratory studies of non-neutral shoulder postures have shown that pro­ longed elevation of the arms (abduc­ tion or flexion of the shoulder) causes extreme levels of muscle fatigue and discomfort.(1,6) Hagberg(7) demonstrated a positive relationship between shoulder elevation and increased risk of tendonitis in a cross-sectional field study. A rela­ tionship between non-neutral neck pos­ ture and the development of disorders has also been well documented.(8) The objective of this article is to intro­ duce a one-page checklist for evaluating cab design of construction equipment. The cab design evaluation checklist was developed, pilot-tested, and used to mea­ sure several characteristics of cab design (see Table I).