Comparison of forward-facing and backward-facing tractor egress

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Falls and near-falls from tractors during ingress and egress are a health hazard that researchers should work to prevent. To gain an understanding of the factors contributing to such falls, a pilot study was completed in which kinematic analysis of tractor egress was performed using three individuals whose heights represent 5th, 50th and 95th population percentiles, respectively. The three participants were instructed to ingress and egress from the tractor. They always faced toward the tractor during ingress, however, egress involved two positions: facing toward the tractor (i.e., climbing down as one climbs down a ladder; hereafter referred to as backward facing egress or BFE) and facing away from the tractor (i.e., stepping down as one walks down a staircase; hereafter referred to as forward facing egress or FFE). Each participant completed three BFE replicates and three FFE replicates on each of the five tractors selected for this pilot study, yielding a total of 90 ingress/egress measurements. The participants’ movements were recorded with two digital video cameras to capture motion in two perpendicular planes. Kinovea motion analysis software was used to complete kinematic analysis. The observed time of descent was greater for BFE than FFE with many of the differences statistically significant at the 5% level. On average, BFE required approximately 1.4 times longer than FFE. Three-point contact was maintained 56% of the time during FFE and 68% of the time during BFE, with this difference significant at the 5% level. Maximum values for excursion of the knee joint ranged from 73 to 131° for FFE and from 44 to 111° for BFE. Although statistical analysis could not be completed because knee flexion was not visible for every step, the data suggest that the activity of FFE requires greater excursion of the knee joint than does the activity of BFE. Jumps from the bottom step to the ground were observed in 3 instances for BFE (7% of BFE trials) and in 26 instances for FFE (58% of FFE trials). Overall, it has been confirmed that kinematic analysis is able to detect differences between forward facing egress (FFE) and backward facing egress (BFE). The experimental evidence suggests that BFE is safer behaviour than FFE.