COMPARISON OF 4 METHODS FOR CARRYING A FIBERGLASS EXTENSION LADDER

This paper describes the results of two studies aimed at comparing fou r methods of carrying a fiberglass extension ladder. The first study w as conducted in the actual work conditions while the other took place in ideal laboratory conditions. Twenty-one telephone technicians parti cipated in the held study while seven participated in the laboratory s tudy together with three subjects having no prior experience with heav y ladder handling. In the field study, the technicians were asked to c arry their ladder with each of the four carrying methods. After the co mpletion of each carrying task, the technician rated the method he had just tried on seven subjective measures. Technicians' heart rate was monitored during the complete experiment. In the laboratory study, a s imilar protocol was used with the difference that the carrying tasks w ere longer since oxygen uptake was also measured. All telephone techni cians had no prior knowledge or practice with three of the carrying me thods tested: they had experience only with the carrying method they u se in their daily work. Results of the held study show that carrying a fiberglass extension ladder on the shoulder with the arm 'Through-the -rungs' imposed the least strain on the cardiovascular system and this method was judged better than or at least equivalent to the carrying method in current use. The results of the laboratory experiment were c onsistent with those of the field study. The other two methods tested yielded a performance that was inferior to that of the method currentl y used by telephone technicians in both the held and laboratory studie s. The results further show that the study performed in actual work co nditions had better validity than the study performed in the laborator y. (C) 1998 Elsevier Science B.V. All rights reserved.