Document ev6QQbV2LKpw5B2Q0K7vEBJjg

60 ROSS A. MC FARLAND surroundings, the location of controls and instruments, and the way the operator performs his duties. A functional concept of accidents should be maintained throughoutr--that is, the errors that may occur while the operator is working at the machine should be anticipated. The repetition or recurrence of near or real accidents clearly indicates a need for redesigning. Another consideration relates to human limitations. It should be assumed that no worker is a perfect one. In fact, he may be far below the ability assumed by the designer. If his duties are too complex, the cumulative burden is great and he may reach or exceed his limits of attention and ability. Finally, a wide margin of safety should be provided to eliminate any possible situation that places the operator near his maximum ability with regard to aptitude or. effort, especially when adverse factors are present.6 1. Operational Job Analysis No engineer would accept an assignment to design a motor unless he'was also provided with information as to what the motor was for, the conditions under which it would operate, and the type of load it was expected to handle. In other words, specifications are required and these rest upon an analysis of the job the motor is to perform. If we view an employee as an intricate industrial machine, then before he is assigned to a given task, the work should be analyzed in terms of demands to be placed on this human machine. No engineer would design a motor to operate under condifiohs 6f extfeme coTd' without"considering-the-possibledamage that might result from this operating condition and providing the neces sary safeguards, such as proper tolerances, lubricants, and the like. Surely, the human machine should receive as much consideration as a motor. The potentiali ties of job analysis for the prevention of industrial accidents are very great, but thus far they have been only partially exploited and developed. Job analysis can be divided into three broad areas: the surround, the ma chine, and the operator. The surround refers to the operational area within which the operator is, required to perform. For example, poorly lighted areas or passages are one of the conditions among which the operator must sometimes perform his work. The second, arga .is the machine. Job analysis can be applied to equipment '^sTgnl0|Jnrem^ma^|mv^mrinpp^fbr^sfety-Hhd"c.prres|oirmngwreduction-- in ihdustr^kw'?d%We'tiiifi area, which deals specifickl)yj^ifh;the selection and placement of personnel,'is generally not included in human engineering. The hazardous features and conditions of some jobs are evident upon casual insp'ectio'n."'N'0"specirh-professional skill is required-todetennine.that-a-power- . driven ripsaw is potentially dangerous to the hands of the operator. The services of a safety engineer are not required to reach the conclusion that the operator may come in contact with the blade. His services become valuable, however, in deciding what kind of a safety device should be employed and just how it should R. A. McFarland, Human Factors in Air Transport Design. McGraw-Hill, New York, 1946. HUMAN ENGINEERING AND INDUSTRIAL SAFETY 61 'A|| ^ die. designed and used. Common sense and unaided observation can, in some inr "?$y'r~'3t:anceS,1)6 ac^ec)uate to identify the potential dangers of a job. The dangerous aspects of other jobs can be identified by knowing some of the ^' ^technical features of the equipment. For example, the danger inherent in some i'i'bioelectric generators when there is a sudden loss of load can be deduced from. B,istir, characteristics of the generator, the turbines, and the controlling valves. ,`J Direct observational and logical procedures can often utilize somr e of the P*. >f*iAr -,special +te.cr*hVnmiqimuie^Os +thVlfa +t havekboeaenn rdlnevvAellAonpAeJd aas. -a1i,d1 ~s in locai.t1ingJ.t1he Jd_a___n__g__er spots in . loll SSulichi1 Aa*iddss AaSs Tmnofltt.iioflTnl--Tpliipc.ttu.lirreA npVhortftrongrrrtarpkVh\xyr, ilMn+teflwrvsriieoTwiresi vwirii+thK aevxnpneriiennncAeAdrl an<* ana'ysis of contro1 movements and forces become especially useful yte '^jobs,that are intricate, those that are part of a more complicated system of 1 `TM`and equipment, and those in which failures and accidents rarely occur. Each ^df''these methods is a tool useful in abstracting from an operator's performance I ` !bbse items that- involve danger to the operator, his fellow workmen, or the inl&A'llation and its personnel. . fel'TOln. such studies, the concept of an error rather than an accident is often 'SKvE*' '/Preferable because of the additional latitude-in the connotation of the term "error." lp^.%KS1.nte corrective action can be taken by the detection of "near accidents," atten- 8*ven to both potential and real accidents. A search for-errors in perform> 'pttf-'1' , 'ie;may uncover near accidents or events that would result in catastrophe under iJijjlpAl circumstances. Indeed, many accidents can result only when more than ^e.rroriBTirad'erln-SDHre'-systems.-oiie-marmake an-error and'the mistake will Isfoinpensated for by another operator or by some characteristic of the maffihery. Serious trouble may develop only when more than one error is made '^Qjrigwhere in the system within a limited period of time.. Thus, some errors can jKii'c .thought of as sufficient conditions for an accident, whereas other errors are Sg^e'c^smy, but not sufficient, conditions for an accidentXA program for reducing '^^ccijpsnts must consider both kinds. wben attention is directed to errors so as to include instances in which ,, sJ^r.`'^riPus trouble might have developed but did not, an observer might spend many m Witching a competent operator without finding:.enough cases'to.. .permit /;P.|^S|s.study and evaluation. Accordingly, special techniques are,needed to.ac- ,, ;^/^&^ptheTSiiF5rrgSp'ee6^FrClTetp5rformanee 'either by'rMpefimefitally increasing ifppfequency of errors or by telescoping time so that an adequate sample of available for study. Some of the typical methods used..in this kind of job ^^malylis will now be examined.2 , l^imemn&~M&tiom^Study-r^-'I:iine and motion-study- has-made-ditbie-direct '"gfifappution to problems in safety. To a considerable extent this can be attributed j^g;|Mmi8mider8tanding of the nature and purpose of this type of . analysis. Time' ^W^ilption study is simply a means for obtaining a description of current methods Sjjjji" It is when the findings from the time and motion study are used as a f|or setting up new and presumably improved methods of . work that disfment comes.