Proceedings of the National Institute for Farm Safety (NIFS) Annual Conference, June 23-27, 2002, Ponte Vedra, Florida. Columbus, OH: National Institute for Farm Safety, 2002 Jun; :1-24
Agriculture continues today as one of the most hazardous industries in the U.S. with comparatively high fatality rates. Hundreds of farmers die each year due to rollovers despite the fact that highly effective engineering controls are available in the form of rollover protective structures (ROPS). In 1999, the Division of Safety Research within the National Institute for Occupational Safety and Health (NIOSH) initiated a four-year project aimed at leveraging new technology to increase ROPS use on tractors. One component of this project is the design and development of cost-effective rollover protective structures (CROPS). The cost of commercially available ROPS average about $900, excluding installation. As an incentive to farmers who may see this price as prohibitive, particularly when retrofitting older tractors, the NIOSH CROPS project aims to design and test specifications for a midsize tractor ROPS that can be assembled by a farmer for less than $425. This project builds on expertise within NIOSH for advanced computer-aided analysis and testing of ROPS, including overturn field testing using a remotely-controlled tractor. In general, the sequence for design of the CROPS is: (1) conceptualization, (2) computer-aided design (CAD), (3) engineering analysis and simulation, (4) prototype fabrication, (5) static testing, (6) field testing, (7) evaluation and redesign. Steps (2) and (3) are completed largely on the computer by use of CAD software to examine the fit and form of the design and engineering analysis software (finite element) to evaluate simulated performance under structural loading. Steps (5) and (6) are completed based upon a physical prototype and the performance requirements of the SAE J2194 standard. Depending on the results of step (7), the process may be repeated. As of May 2002, four CROPS prototypes have been evaluated. Each prototype was fabricated from common structural materials conforming to popular consensus standards. The prototype designs have used standard steel pipe and rectangular tubing. To date, only prototype 4, which was constructed from 2"x4"x1/4" rectangular tubing, has successfully passed the first longitudinal test of SAE J2194 for a tractor reference mass of 3728 kg (8220 lb). This reference mass is the maximum mass listed for a Ford 4600 in the Nebraska tractor test. For a Ford 4600, the minimum reference mass required by the SAE J2194 standard (unladen with no ballast) is estimated at 2667 kg (5880 lb) from the Nebraska Tractor Test. Prototype 4 has successfully passed the longitudinal, vertical crush, and transverse load tests for a reference mass of 2351 kg (5184 lb). The goal of the CROPS project is to increase ROPS usage on tractors by providing farmers with lower cost ROPS. The product of the project will be the specifications for an inexpensive ROPS design which could easily be assembled. While, it cannot be easily estimated at this point in time how many farmers could benefit from a CROPS design, it is anticipated that developing such designs may provide an additional option to promote safer tractor operation by America's farmers.