The Growing Problem in Truck Cab Design
by Blake McGowan, CPE
A very important study was published in the October 2012 issue of Human Factors titled, “U.S. Truck Driver Anthropometric Study and Multivariate Anthropometric Models for Cab Design.” I am always impressed when leaders from NIOSH, reputable universities, and industry collaborate on projects that result in applied and usable information; this is such a study.
Trucking is one of the most hazardous occupations, including fatal and non-fatal incidence, in the United States. Truckers spend long hours on the road, and the design of the truck cab can have a significant impact on safety and comfort. With the changes in U.S. anthropometrics, especially the changes in body mass index (BMI), there is a need to update the trucker anthropometrics since the previous data was provided in the 1970s and 1980s.
In recent years, major trucking manufacturers have begun a transition from the traditional percentile approach (5th to 95th percentile) to a multivariate accommodation model (MAM) approach to cab design. The MAM approach tries to reduce a large number of measured variables to a smaller number (two or three) of principle components (PC). So, after measuring the anthropometrics (35 different dimensions) on 1,950 truckers (1,779 males and 171 females) across the continental U.S. and across ethnic, gender, and age ranges, what did they find? Principle results include the following:
- Males truck drivers are significantly shorter (12 mm) and heavier (13.5 kg) than the general U.S. population.
- Male truck drivers have greater thigh and waist circumference (90 mm and 13.5 mm, respectively) than the general U.S. population.
- Compared to 30 years ago, male truck drivers are larger in abdominal depth, sitting forearm-to-forearm breadth, hip breadth, sitting waist circumference, and body weight.
These changes in truck driver anthropometrics may reflect the sedentary nature of the trucking occupation and the ongoing obesity epidemic in the U.S.
So how can we apply this information? A set of multivariate anthropometric models, which accommodate 95% of the current truck driver population, has been developed to help with future truck cab design. These models may also be applied when designing vehicle cabs for delivery occupations (local FedEx or UPS deliveries), sales representatives (e.g., traveling sales agents for the pharmaceutical industry), or even field workers. There is a great deal of useful data in this study that every ergonomist should apply to improve safety and comfort within the workforce.