Understanding the requirements for a blind-spot monitoring system on tractors from the operator’s perspective

Unintentional run-overs occur because the operator of a tractor is unable to physically see all around the machine. Therefore, there is a need to devise an effective blind-spot monitoring system for tractors to prevent unintentional run-overs. The purpose of the study was to identify the locations of blind spots around two types of tractors (i.e., with and without a front-end loader), with the ultimate goal of conceptualizing a blind-spot monitoring system capable of eliminating all existing blind spots. Grids were constructed around all four sides of the tractors to determine the presence of blind spots for drivers of varying sitting height (i.e., 5th, 50th and 95th percentile male for erect and slumped postures) at four horizontal planes representing people of varying stature who might be in the vicinity of the tractor (i.e., standing male, standing female, standing child, kneeling adult). Generally, the proportion of markers not visible decreased as the sitting height increased. Differences between erect and slumped sitting postures were not statistically different suggesting this variable could be ignored in the assessment of blind spots around tractors. The proportion of the markers not visible to the operator varied from 0 to 34%, with higher values observed for the tractor with the front-end loader installed. Values were as high as 42% of the markers not visible for the condition where a passenger was present in the passenger/trainer seat. Use of the existing rear-view mirrors eliminated only a small fraction of the blind spot area around the tractors. Through trial and error, it was determined that five and eight cameras would be required to fully detect the entire blind spot area around the two tractors selected for this study. A blind-spot monitoring system composed of five or eight cameras would create substantial additional monitoring burden for the tractor operator and, therefore, is not a feasible solution. A hybrid blind-spot monitoring system consisting of cameras and proximity sensors warrants further investigation.