Development and validation of a hazard self-assessment worksheet for tractors with modified controls

Incidents involving large machinery are a leading cause of fatal and nonfatal agricultural injuries. Many farmers with disabilities choose to modify their work environments to accommodate their personal abilities. Modified tractors may present greater risk to the operator as they are often one-of-a-kind designs that have not been subjected to rigorous safety testing. A reliable instrument for self-assessment of tractor hazards would facilitate the identification of factors that could contribute to losing control of the tractor, personal injuries, or repetitive strain injuries. The objective of this project is to develop and validate a worksheet that could be used by farmers or rehabilitation professionals to identify hazards in agricultural operator enclosures with modified controls. The worksheet will also provide an opportunity to estimate the risk associated with the potential hazards; this will provide a means to prioritize existing hazards in terms of the likelihood and severity of potential injuries that may result. The hazard self-assessment worksheet was created based on research on tractor-related agricultural hazards and injuries. A pilot study was conducted to assess the reliability and validity of the worksheet. Six participants used the worksheet to evaluate three staged tractor cabs with modified controls concurrently with an expert rater. The kappa statistic was used to assess inter-rater agreement. Based on the results of the pilot study, the overall inter-rater reliability and concurrent criterion validity appear to be acceptable. The overall inter-rater reliability for the hazard identification portion of the worksheet had an observed proportion of agreement of 0.809 and an overall kappa of 0.427 which indicates moderate agreement. The overall concurrent criterion validity for the hazard identification portion of the worksheet had an observed proportion of agreement of 0.843 and an overall kappa of 0.555 which also indicates moderate agreement. The risk estimation portion of the worksheet could not be adequately assessed due to low prevalence of situations where the participants found that the potential hazards were present and proceeded to estimate the associated risk. Based on the results of the expert panel review, the worksheet items are adequately relevant and clear, but the wording on some could be improved. The HSAW show promise as a self-administered tool for hazard identification; however, it should be assessed in a full scale study involving farmers with disabilities to verify the estimates of reliability and validity presented here.