Mobile Agricultural Research Laboratory is Designed for Operator Comfort
Authors: Prussia Stanley E. , Shewfelt Robert L. 
Published: January 2012

Studies of changes in vegetable quality during commercial handling require extensive periods of research at production locations to measure initial physical and chemical characteristics. When working in open air facilities it was found that required accuracies could not be maintained and that some procedures could not be completed. High temperatures, wind, dust, and other adverse environmental conditions severely reduced human and equipment performance. The success of mobile facilities ranging from medical clinics to bookmobiles suggested the possibility of a mobile laboratory for on-site agricultural research. The value of Human Factors principles was recognized for designing a general purpose research laboratory. A large (2.44 m X 9.75 m) cargo trailer was purchased to give the space and durability needed for repeated trips lasting several days. In addition to laboratory space, living facilities were needed for up to three researchers while at remote field sites.

The completed mobile laboratory performed superbly on several trips in 1982 and 1983. Users of the lab compared it to a small but efficient kitchen which verified the value of attention to arrangement (work triangle, offset work stations, cabinet locations, etc.) and anthropometric principles (aisle width, counter height, adjustable stools, knee well dimensions, ceiling height, etc.). Productivity in the mobile laboratory was higher than in a modern laboratory in a Food Science building; possibly due to shorter distances between work materials and the presents of only necessary equipment.

Quantitative measurements showed the mobile laboratory conformed to established limits for environmental factors. An air conditioner and a furnace maintained the interior within ASHRAE specified exposure limits dispite a 5°C to 40°C outside temperature. An exhaust fan with 4.53 m3/min capacity provided adequate ventilation (10 air changes per hour as recommended for laboratory type space). Illumination was adequate for general office work (1076 lux) and for highly difficult inspection task (2153 lux) at the work stations when using either battery powered or generator powered fluorescent lamps.

Noise and vibration problems from the 10,000 watt electrical generator were minimized by placing it outside the laboratory on special vibration isolators. Vibrations from an air compresser were isolated by mounting it on the generator frame. Acceleration measurements at the sleeping section and at the work stations had a predominate frequency of 60 Hz. Measured acceleration values corresponded to ISO exposure limits (fatigue scale) ranging from 3.5 to 7.0 hours. Lack of fatigue symptoms after 10 hours exposure could be due to factors such as conservative standards, periodic movement, and reduced vibration under field conditions. A small battery powered water pump mounted under the sink caused noticeable vibration during short periods of operation. Background noise outside the laboratory (50.7 dBA) was reduced to 35 dBA with windows and doors closed. Operating the generator and air conditioner increased the noise level to 72 dBA. No speech interference was noticed for people at extreme ends of the laboratory. Outside the laboratory the noise level was 87 dBA at 1.83 m from the generator which is less than the 90 dBA eight hour exposure limit guideline given in The Walsh-Healey Act.

A substantial improvement in working conditions has been realized by developing a mobile research laboratory. Human factors principles were found to be very beneficial when making design decisions and evaluating the finished unit. Common sense judgments were also needed when principles conflicted or compromises were necessary between economic considerations and the optimum design from the human factors point-of-view. It is certain that the use of established principles and standards minimized expensive rework that could have otherwise been necessary due to unacceptable noise and vibration levels.