(1996) anthropometry and biomechanics

HFDG Section 14 contents

January 15, 1996 FAA William J. Hughes Technical Center 14-i

Section 14 contents

14 Anthropometry and biomechanics ............................. 14-114.1 Generalapplication ofanthropometricandbiomechanicaldata ............................................................................................... 14-114.1.1 Userpopulation ............................................................................................... 14-1

P 14.1.1.1 Use of data ............................................................... 14-2P 14.1.1.2 Data to be used ........................................................ 14-2P 14.1.1.3 Using population extremes ...................................... 14-2

14.1.2 Usingdesign limits ............................................................................................... 14-2

P 14.1.2.1 Selecting the correct human physical and associated measurement characteristics .................... 14-3

P 14.1.2.2 Selecting the appropriate distribution information ............................................................... 14-4

P 14.1.2.3 Selecting the correct percentile statistic ................... 14-4P 14.1.2.4 Clearance dimension at the 95th percentile .............. 14-6P 14.1.2.5 Clearance dimension at the 99th percentile .............. 14-7P 14.1.2.6 Limiting dimension at the 5th percentile ................. 14-7P 14.1.2.7 Limiting dimension at the 1st percentile .................. 14-7P 14.1.2.8 Adjustable dimensions ............................................. 14-7P 14.1.2.9 Sizing determinations .............................................. 14-7P 14.1.2.10 Critical life support equipment ................................ 14-8

14.1.3 Avoidingpitfalls in applyinganthropometric data ............................................................................................... 14-8

P 14.1.3.1 Misuse of the 50th percentile or of the average ....... 14-8P 14.1.3.2 Misperception of the typically sized person ............. 14-8P 14.1.3.3 Summation of segment dimensions ......................... 14-8

Section 14 contents HFDG

14-ii FAA William J. Hughes Technical Center January 15, 1996

14.1.4 Solving acomplex sequence ofdesign problems ............................................................................................... 14-9

P 14.1.4.1 Design to body positions and motions of the tasks .......................................................................... 14-9

P 14.1.4.2 Construction or collection of unique position data ........................................................................... 14-9

P 14.1.4.3 Design reference points and zones ........................... 14-9R 14.1.4.4 Building and using reach envelopes ....................... 14-10R 14.1.4.5 Building visual envelopes or footprints ................. 14-10R 14.1.4.6 Building design solutions ...................................... 14-10P 14.1.4.7 Effects of clothing ................................................. 14-10

Exhibit 14.1.4.7 Additive effects of clothing on anthropometric measures ............................................. 14-11

P 14.1.4.8 Effects of tools and equipment lifted or carried ..... 14-12

14.1.5 Use ofdistribution andcorrelation data ............................................................................................. 14-13

R 14.1.5.1 Gaussian distribution of measurement values on a single human physical characteristic .................... 14-13

Exhibit 14.1.5.1 Percentile values .................................... 14-13

R 14.1.5.2 Using bivariate distribution data ............................ 14-13R 14.1.5.3 Use of correlation and multiple

correlation data ....................................................... 14-14

14.1.6 Use of models ............................................................................................. 14-14P 14.1.6.1 Data applicable to the design problem ................... 14-15P 14.1.6.2 Common errors ...................................................... 14-15P 14.1.6.3 Use of design limits approach ................................ 14-15P 14.1.6.4 Model treatment of multiple variables ................... 14-15P 14.1.6.5 Joint mobility and reach interaction ....................... 14-15

14.2Anthropometricvariability factors ............................................................................................. 14-15

R 14.2.1 Foreign populations .................................................. 14-15R 14.2.2 Race ......................................................................... 14-15R 14.2.3 Body slump .............................................................. 14-15


January 15, 1996 FAA William J. Hughes Technical Center 14-iii

14.3Anthropometricandbiomechanicaldata ............................................................................................. 14-1614.3.1 Data usage ............................................................................................. 14-16

P 14.3.1.1 Use of anthropometric and biomechanical data ..... 14-16P 14.3.1.2 Task considerations ............................................... 14-16

14.3.2 Static bodycharacteristics ............................................................................................. 14-16

R 14.3.2.1 Static data .............................................................. 14-16

Exhibit 14.3.2.1 Static human physical characteristics (head) ........................................................ 14-18 Exhibit 14.3.2.1 Static human physical characteristics (seated) ...................................................... 14-22 Exhibit 14.3.2.1 Static human physical characteristics (standing) .................................................. 14-26 Exhibit 14.3.2.1 Static human physical characteristics (standing position and hands) .................... 14-30

P 14.3.2.2 Relevant static anthropometric data ....................... 14-17

14.3.3 Dynamic(mobile) bodycharacteristics ............................................................................................. 14-3014.3.3.1 Rangeof whole body motion ............................................................................................. 14-30

P 14.3.3.1.1 Trunk movement ................................................. 14-31P 14.3.3.1.2 Whole body movement ....................................... 14-31

14.3.3.2 Joint motion ............................................................................................. 14-31P 14.3.3.2.1 Single joint movements ....................................... 14-31

Exhibit 14.3.3.2.1 Joint movement ranges ........................ 14-32

P 14.3.3.2.2 Range of motion for two joints ............................ 14-34 Exhibit 14.3.3.2.2 Change in range of joint movement with movement in an adjacent joint ................ 14-35

P 14.3.3.2.3 Design limit approach ......................................... 14-35

Section 14 contents HFDG

14-iv FAA William J. Hughes Technical Center January 15, 1996

P 14.3.3.2.4 Use of this guides dynamic data ......................... 14-36

14.4 Reach ............................................................................................. 14-36P 14.4.1 Task and body position effects ................................. 14-36R 14.4.2 Reach envelope data collection ................................ 14-37

Exhibit 14.4.2 Reach envelopes in vertical and horizontal planes .............................................................. 14-37

P 14.4.3 Reach envelopes for control actions ......................... 14-38P 14.4.4 Reach envelope interaction with the reach task ........ 14-38

Exhibit 14.4.4 (a) Touch, grip, and grasp functions that interact with arm reach ............................... 14-38

Exhibit 14.4.4 (b) Thumb and forefinger grasp boundary data for females in the 46 cm and 61 cm horizontal planes .................................. 14-40

Exhibit 14.4.4 (c) Thumb and forefinger grasp boundary data for females in the 0 and -15 cm vertical planes ............................................. 14-41

R 14.4.5 Strength or fine manipulation ................................... 14-42

14.5 Humanstrength andhandling capacity ............................................................................................. 14-4214.5.1 Musclestrength factors ............................................................................................. 14-42

14.5.2 Exertedforces ............................................................................................. 14-43

R 14.5.2.1 Maximum young male force or resistance for a control ............................................................ 14-43

Exhibit 14.5.2.1 Male muscle strength of the arm, hand, and thumb for control forces (5th percentile values) ...................................................... 14-44

P 14.5.2.2 Increasing strength values ...................................... 14-45P 14.5.2.3 Decremented strength values ................................. 14-46R 14.5.2.4 Comparative strength ............................................. 14-46R 14.5.2.5 Preventing tremor in positive control

performances .......................................................... 14-46

14.5.3 Push andpull forces ............................................................................................. 14-47

R 14.5.3.1 Horizontal direction of force .................................. 14-45


January 15, 1996 FAA William J. Hughes Technical Center 14-v

Exhibit 14.5.3.1 Horizontal push and pull forces that can be exerted ............................................................ 14-47

R 14.5.3.2 Vertical direction of force ...................................... 14-48

Exhibit 14.5.3.2 Static muscle strength data for vertical pull exertions .................................................. 14-49

R 14.5.3.3 Forces for handles .................................................. 14-48

14.5.4 Lifting andcarrying ............................................................................................. 14-52

P 14.5.4.1 Lifting and carrying limits ..................................... 14-52

14.6 Design forphysical comfort ............................................................................................. 14-52

R 14.6.1 Adjustment capabilities ............................................ 14-52R 14.6.2 Restrictions to movement ......................................... 14-52R 14.6.3 Body support ............................................................ 14-53P 14.6.4 Body posture ............................................................ 14-53P 14.6.5 Demands upon tasks ................................................. 14-53

HFDG 14 Anthropometry and biomechanics

January 15, 1996 FAA William J. Hughes Technical Center 14-1

14 Anthropometry and biomechanicsDesigners and human factors specialists incorporate scientificdata on human physical capabilities into the design of systemsand equipment. Human physical characteristics, unlike those ofmachines, cannot be designed. However, design oversight canplace unnecessary demands and restrictions upon user personnel.

Definitions. Anthropometry is the scientificmeasurement and collection of data about human physicalcharacteristics and the application (engineeringanthropometry) of these data in the design and evaluationof systems, equipment, manufactured products, human-made environments, and facilities. Biomechanicsdescribes the mechanical characteristics of biologicalsystems, in this case the human body, in terms of physicalmeasures and mechanical models. This field isinterdisciplinary (mainly anthropometry, mechanics,physiology, and engineering). Its applications addressmechanical structure, strength, and mobility of humans forengineering purposes.

This final technical section of the HFDG provides additionalanthropometric and biomechanics data beyond that used inprevious technical sections. Previous data are cross referenced,where appropriate. Unlike the other sections, this sectionprovides more guidance about the nature of the data, its selection,and its proper use. It provides rules for applying the vast amountof human form data available to specific design fit, function, andhuman task performance.

The section also covers application principles and their resultingrules, human body measurement data (static and dynamic), rangeof motion and strength data, as well as comfort information.

14.1 Generalapplication ofanthropometricandbiomechanicsdata

In this document, body size, strength, and mobility data arepresented to represent the current FAA maintenance population.In the future, this population will include a wider range of ethnicbackgrounds. Minorities and females are expected to increase.The average age is expected to decrease. These changes will beimportant for future systems design.

In this general section, design criteria and guidelines are givenfor: (1) ascertaining user population data, (2) using the designlimits approach, (3) avoiding pitfalls in applying the data, (4)using distribution and correlation data, (6) solving designproblems, and (7) using models.

14.1.1 Userpopulation

Anthropometric data are most appropriate when they are derivedfrom a survey of the existing worker population of interest. Sincethe sub-population associated with the FAA has not beensurveyed, information from substitute sources is used as a basisfor design.

14 Anthropometry and biomechanics HFDG

14-2 FAA William J. Hughes Technical Center January 15, 1996

P 14.1.1.1 Use of data. Anthropometric and biomechanics datashall be used in the design of systems, equipment (includingpersonal protection equipment), clothing, workplaces,passageways, controls, access openings, and tools.

Discussion. The humans interface with other systemcomponents needs to be treated as objectively andsystematically as are other interface and hardwarecomponent designs. It is not acceptable to guess abouthuman physical characteristics or to use the designersown measurements or the measurements of associates.Application of appropriate anthropometric andbiomechanics data is expected.

P 14.1.1.2 Data to be used. Designers and human factorsspecialists shall use the anthropometric and biomechanics dataprovided in this guide. If additional data are needed, they shalluse the more complete data given in DoD-HDBK-743. If otherreference or new data collections are considered, the contractorshall obtain the approval of the acquisition program office.

Discussion. If this guide does not present data needed forthe problem at hand, the designer will have to selectappropriate sample information from DoD-HDBK-743.In that handbook, the 1988 military male and femalesurvey distributions can be used to represent FAAmaintenance personnel when needed, as it represents themost comprehensive samples available. Note that civilianworking populations could be expected to have a largerrange of sizes and ages than the military. Samples withcomprehensive measures are not available.

P 14.1.1.3 Using population extremes. Designers and humanfactors specialists shall draw upon the extremes of the larger malepopulation distribution and the extremes of the smaller femalepopulation distributions to represent the upper and lower rangevalues, respectively, to apply to anthropometric andbiomechanics design problems.

Discussion. The use of separate male and femalepopulation data is a conservative approach that results inmore inclusive design dimensions than the samepercentiles would from a composite population.

14.1.2 Usingdesign limits

Initial rules in this section address the design limits approach. Tounderstand this approach it is helpful to consider the overall stepsand choices that one makes in applying anthropometric andbiomechanics data. The design limits approach entails selectingthe most appropriate percentile values in population distributionsand applying the appropriate associated data in a design solution.These steps are listed in this introductory material and areexplained in detail in the initial three guidelines of thissubsection. If the reader has applied the design limit approachand understands it, the reader can skip the rest of thisintroductory material as well as the explanations associated withthe first three guidelines, do not skip the guidelines.



Definition. The design limits approach is a method ofapplying population or sample statistics and data abouthuman physical characteristics to a design so that adesired portion of the user population is accommodatedby the design. The range of users accommodated is afunction of limits used in setting the population portion.

To understand the design limits approach it is helpful to considerstep by step the choices that design personnel make in applyingthese human physical data.

a. Select the correct human physical characteristic and itsapplicable measurement characteristic (description) forthe design problem at hand.

b. Select the appropriate population, representativesample, or guideline information on the selected humanphysical characteristic and measurement description toapply to the design problem.

c. Determine the appropriate statistical point(s), usuallypercentile points from guideline information or from thesample distribution(s) in order to accommodate a desiredrange of the human characteristic within the distributionof the user population.

d. Read directly or determine statistically the measurementvalue(s) that corresponds to the selected statisticalpoint(s) relevant to the population distribution.

e. Incorporate the measurement value as a criterion for thedesign dimension, or in the case of biomechanics data,for the movement or force solution in the design problem.

The design limits approach is accomplished during the selectionof percentile value(s) as the statistical point(s) in step c above.Steps (a) and (b) are explained under the first two rule paragraphsbelow. Steps (c), (d) and (e) are explained under the third ruleparagraph below. The terms in bold above are defined in therules that follow. An example problem covering all steps followsthe third rule in paragraph 14.1.2.3. Different percentile valuesapply to design issues involving clearance, reach limits,adjustments, and sizing. These types of design limits problemsare covered in paragraphs 14.1.2.4 through 14.1.2.9.

P 14.1.2.1 Selecting the correct human physical and associatedmeasurement characteristics. Design personnel shall selecthuman and measurement characteristics that are relevant to thecomponent of design under consideration and are based upon:

a. an analysis of human tasks associated with the system,equipment, facility, or environment,

b. consideration of normal, degraded, or emergency modesof task activities, and



c. consideration of the importance and frequency ofexpected task performance.

Definitions. Human physical and associatedmeasurement characteristics refer to specific physical,mobility, or strength features of human users and to theexplicit way that a human feature or capability ismeasured for use as general anthropometric orbiomechanics data or as data for a specific design.

Explanation. (Step a from 14.1.2). Select the correcthuman physical characteristic and its applicablemeasurement description for the design problem at hand.The associated measurement description tells howmeasurements are taken for population or sampledistribution data. The decision to use a particularcharacteristic is one of selecting the correct variable(s) forthe problem. If the problem calls for biomechanicsinformation, for example, strength information, the sameinitial step of identifying the specific human characteristicand how it is measured would apply.

P 14.1.2.2 Selecting the appropriate distribution information.When the design limits approach is used, designers and humanfactors specialists shall select the appropriate sample distribution(including the male, female, and nationality compositions) fromguideline, handbook, or survey sources.

Discussion. Information presented in this guide isderived from the most relevant distributions for the usersand for the general problem areas. Part of the selectionprocess may be to choose the most appropriate male orfemale distribution information.

Explanation. (Step b from 14.1.2). Select theappropriate population, representative sample, orguideline information appropriate for guideline data onthe selected human physical characteristic and itsmeasurement description that applies to a design problem.

A population distribution has certain definingparameters. For instance, a population mean and varianceare sufficient to define a known normal (or Gaussian)distribution (the bell shaped curve associated with thevariability of many human characteristics).Usually, the entire population of users has not beenmeasured so sample distribution data and statistics aregenerally used. Information from large samples canestimate population parameters and thus can be used.

P 14.1.2.3 Selecting the correct percentile statistic. Designcriteria for a human physical integration problem shall be basedupon the range of the population to be accommodated. Designersand human factors specialists shall determine the appropriatestatistical points, usually percentile statistics, to accommodate an



appropriate range of the population distribution for the specificdesign problem.

Definitions. The percentile statistic is determined byranking all data values (using the applicable measurementvalues related to the selected human physicalcharacteristic) in the sample and determining thepercentage of data that fall at or below a specific datumvalue. This percentage is known as the percentile value(or point) of the selected datum.By definition, the point below which five percent of thedata values fall is known as the 5th percentile statistic.The point below which one percent of the data falls isknown as the 1st percentile. Similarly, the midpoint ofthe distribution is the point below which 50 percent of thedata falls and is defined as the 50th percentile. Toaccommodate 95 percent of the population or sample,choose the 95th percentile statistic, to accommodate allbut the top one percent choose the 99th percentilestatistic.

Explanation. (Step c from 14.1.2). Determine theappropriate statistical point(s), usually percentile points,from guideline information or from a sample distribution,in order to accommodate the desired range of the humancharacteristic within the distribution of the userpopulation.

Usually, for design purposes, it is impractical toaccommodate the extremes of the distribution becausethere is so much variability at the extremes and so fewcases. often, persons who are extreme in dimensionalmeasurement values (in the lowest or highest one percent)know it, and they behave so as to compensate for thedesigned portions of their environments.

In step c, designers select the most applicable statisticalpoint(s) from the appropriate distribution to accommodatethe portion of the population that is appropriate to thedesign problem. The design limits approach involvesselecting the appropriate percentile statistic(s). It waspreviously noted that different kinds of design problems(clearance, reach, adjustment, and sizing) call for differentstrategies and result in the selection of different percentilestatistics.

(Step d). Read directly or determine statistically theappropriate measurement value (or datum value) thatcorresponds to the selected statistical point relevant to thepopulation (or applicable sample) distribution.For any percentile statistic used as applicable to a designproblem, there is a measurement value or data point thatcorresponds to the criterion percentile statistical value.This measurement value can be calculated or counted



from the rank order data distribution, or it can be readdirectly from a tabular or graphical representation of thedistribution.

If population distribution characteristics (for example,normality) and population parameters (for example, meanand variance) are known, then other statistical propertiescan be determined (for instance, percentiles andassociated measurement values (see paragraph 14.1.5.1).(Step e). Incorporate the measurement value as acriterion for the design dimension (or, in the case ofbiomechanics data, for the movement or force solution) inthe design problem.

The actual measurement value is used as the designdimension, force, or movement solution to the designproblem at hand. Since the example design problem isone of accommodating the reach capabilities, the designerwill chose the female distribution to represent the shorterreach capabilities in the population.

Example. A designer who has an application probleminvolving human reach capabilities decides (step a) thatthe human physical characteristic "functional (thumb-tip)reach" is applicable to this reach problem. In this case theassociated measurement description is as follows: thehorizontal distance from the wall to the tip of the thumb ismeasured with the subjects shoulders against a wall, thearm extended forward, and the index finger touching thetip of the thumb. (See exhibit 14.3.2.1, physicalcharacteristic 43.) ( Step b) The designer would like tohave distribution information from a compositepopulation which includes both male and female data andwhich represents the applicable FAA population. Sinceno such survey data exist for this population, this guidedirects (14.1.1.2) that substitute distribution data forseparate male and female populations be used (see exhibit14.3.2.1). Since the example design problem is one ofaccommodating the reach capabilities, the designer in stepb will chose the female distribution to represent theshorter reach capabilities in the population. In step c themost appropriate percentile statistic would be the 5thpercentile of the female sample distribution. This pointwould assure that the reach of almost all male and femalepersonnel except those smaller than the 5th percentilefemale would be accommodated. In step d of theexample, the measurement value for the 5th percentilefemale is 67.7 cm (26.7 in) as read from exhibit 14.3.2.1,physical characteristic 43. In step e of the design exampleabove, the 67.7 cm (26.7 in) value would be used as thecriterion dimension in the design to accommodatepersonnel reach.

P 14.1.2.4 Clearance dimension at the 95th percentile. Designclearance dimensions which must accommodate or allow passage



of the body or parts of the body shall be based upon the 95thpercentile of the male distribution data.

P 14.1.2.5 Clearance dimension at the 99th percentile. If acertain clearance design dimension is critical to the activities ofthe entire population or could be life threatening to likely userswho are at the larger extremes of the distribution, then a humanmeasurement value that is at least the 99th percentile male shallbe used as the criterion design dimension.

Discussion. Whole body clearance dimensions forfrequently used passageways and dimensions for criticalescape hatches need to be based on the 99th percentilestatistic. This practice ensures 99 percent of the userpopulation who are smaller than this measurement valuewill have proper clearance.

P 14.1.2.6 Limiting dimension at the 5th percentile. Limitingdesign dimensions, such as reach distances, control movements,display and control locations, test point locations, and handrailpositions, that restrict or are limited by body or body part size,shall be based upon the 5th percentile of female data forapplicable body dimensions.

Discussion. For example, the maximum height from floorlevel to an accessible part of any piece of equipment needsto be within reach of the 5th percentile female maintainer,which will ensure that at least 95 percent of the userpopulation can access this part of the equipment.

P 14.1.2.7 Limiting dimension at the 1st percentile. If certainlimiting design dimensions are critical to the activities of theentire population or could be life threatening to likely users whoare at the smaller extremes of the applicable distribution, then the1st percentile of the female distribution shall be used as the basisfor the criterion dimension.

Discussion. Dimensions for reaching emergency orlifesaving equipment are examples where access cannotbe denied to the smaller extremes of the population.

P 14.1.2.8 Adjustable dimensions. Any equipment dimensionsthat need to be adjusted for the comfort or performance of theindividual user shall be adjustable over the range of the 5th to95th percentiles.

P 14.1.2.9 Sizing determinations. Clothing and certain personalequipment dimensions that need to conform closely to thecontour of the body or body parts shall be designed and sized toaccommodate at least the 5th through the 95th percentile range.If necessary, this range shall be accommodated by creating anumber of unique sizes, where each size accommodates asegment of the population distribution. Each segment can bebounded by a small range of percentile values.



P 14.1.2.10 Critical life support equipment. Dimensions or sizesof critical life support equipment shall accommodate, at least, therange defined by the 1st through the 99th percentiles of thedistribution.

14.1.3 Avoidingpitfalls in applyinganthropometric data

There are several common errors to be avoided by designerswhen they apply anthropometric data to design. These are: (1)designing to the midpoint (50th percentile) or average, (2) themisperception of the typical sized person, (3) generalizing acrosshuman characteristics, and (4) summing of measurement valuesfor like percentile points across adjacent body parts.

P 14.1.3.1 Misuse of the 50th percentile or of the average. The50th percentile or mean shall not be used as design criteria as itaccommodates only half of the users.

Discussion. When the population distribution is Gaussian(normal), the use of either the 50th percentile or theaverage for a clearance would, at best, accommodate halfthe population.

P 14.1.3.2 Misperception of the typically sized person. Designersor human factors specialists shall not use the concept of atypically sized person where the same percentiles values areexpected across many dimensions. A person at the 95 percentilein height is unlikely to measure at the 95th percentile in reach orother dimensions. A percentile value and its measurement valuethat pertains to a particular body part shall be used exclusivelyfor functions that relate to that body part.

Discussion. When the middle 30 percent of a populationof 4000 men was measured on 10 dimensions, only one-fourth of them were "average" in a single dimension(height), and less than 1 percent were average in fivedimensions (height, chest circumference, arm length,crotch height, and torso circumference). Keeping in mindthat there is not an "average person," one also must realizethat there is not a "5th percentile person" nor a "95thpercentile" person. Different body part dimensions arenot necessarily highly correlated. An implication is thatone can not choose a person who is 95 percentile instature as a test subject for meeting 95 percentilerequirements in reach or other dimensions.

P 14.1.3.3 Summation of segment dimensions. Summation of likepercentile values for body components shall not be used torepresent any human physical characteristic that appears to be acomposite of component characteristics.

Discussion. The 95th percentile arm length, for instance,is not the addition of the 95th percentile shoulder-to-elbow length plus the 95th percentile elbow-to-handlength. The actual 95th percentile arm length will besomewhat less than the erroneous summation. Todetermine the 95th percentile arm length, one must use a



distribution of arm length rather than component partdistributions.

14.1.4 Solving acomplex sequence ofdesign problems

In this section, rules are presented for approaching complexdesign problems that requires the consideration of a sequence ofrelevant design reference locations (such as seat reference pointsand eye reference zones), human physical characteristics,statistical points, and measures. The recommended approachinvolves identifying the necessary human activities and positionsand establishing reference points and envelopes for the necessaryactivities. These envelopes impact the location and design ofcontrols and displays as well as the placement of work surfaces,equipment, and seating accommodations. The effects of clothingor carried equipment are then used to expand the dimensions.

P 14.1.4.1 Design to body positions and motions of the tasks.Design personnel shall base the necessary operator andmaintainer body positions and motions on personnel tasks to beperformed during normal, degraded, and emergency modes ofoperations and maintenance. If the human physicalcharacteristics associated with common or mobile workingpositions as presented and illustrated in section 9.4 are applicableto the jobs and tasks, the associated distribution and measurementvalues shall be used.

P 14.1.4.2 Construction or collection of unique position data. Ifthe common and mobile working positions data in section 9.4 ofthis guide do not represent the unique working positionsassociated with a design, then design personnel shall constructthe applicable human physical characteristics and measures fromthe static and dynamic data provided later in sections 14.3.2 and14.3.3 or in DoD-HDBK-743. If no applicable data can be foundor calculated for important design measures, then, with the priorapproval of the acquisition program office, sample measures shallbe taken on appropriate personnel for the unique workingpositions.

Discussion. Anthropometric measurement needs to bedone by professionals because there are manycomplexities and potential interactions among positions ofbody segments, as well as many technical points andpitfalls to avoid in measurement practice. Samplemeasurement methods can be found in Roebuck,Kroemer, and Thomas, 1975.

P 14.1.4.3 Design reference points and zones. Design referencepoints or zones that are key to the relationship betweenpersonnel and hardware or facility design shall be based upon theanthropometry of the necessary working positions. Suchreference points and zones include seat reference points, armrotation points, eye reference points or zones, visual envelopes,and mobility or comfort adjustment ranges. These referencepoints may have design practice definitions in certain applicationarea such as cockpit design or commercial seating. Thesestandard practices can be used, when applicable. However forboth standard or unique designs practices, explicit definitions



used shall accompany each specific application project and therelationships between these points or zones, user physicalcharacteristics, and task requirements shall be explicit.

R 14.1.4.4 Building and using reach envelopes. If reach dataprovided in this guide (see section 14.4) do not apply to a specificdesign problem, then reach design dimensions or envelopes fordesign use should be constructed considering:

a. one-handed or two-handed operation,

b. grasp requirements which may affect the functional reachenvelope,

c. positional relationship of a shoulder reference point orarm rotation point to the seat back, seat reference point, orother posture reference or design reference points, and

d. the appropriate samples and anthropometricmeasurements from the data provided in this guide or inDoD-HDBK-743 (see paragraph 14.1.1.2).

R 14.1.4.5 Building visual envelopes or footprints. Once eyereference points and or zones are established, design personnelshould project the visual areas around the line of sight for visualtasks. Visual envelopes or footprints can show if equipmentlocations may interfere with necessary visual tasks. Similarly,they show where displays can be located to ensure appropriatelegibility and information use. Paragraph and exhibit 7.1.2.6.9address display locations in relation to line-of-sight perspectives.

R 14.1.4.6 Building design solutions. Many problems associatedwith integrating human physical characteristics into a designinvolve building a series of dimension criteria. If feasible, eachcriterion dimension should be based upon the design limitapproach to the appropriate single human physical characteristicfor the body segment appropriate to the design problem. Staticand dynamic data (see section 14.3) are used as the design detailsare planned and iterated. If appropriate, composite characteristicsand measures should be used as addressed in paragraph 14.1.5.3.

Discussion. In design work, measurements are seldomused alone. Sitting height and functional reach are used inthe design of consoles, while hip breadth, sitting andpopliteal height are required for the design of seating.

P 14.1.4.7 Effects of clothing. Because most anthropometric datapresented in this guide and in other data sources represent nudebody measurements (unless otherwise indicated), suitableallowances shall be made for light, medium, or heavy clothingand for any special protective equipment that is worn. Exhibit14.1.4.7 illustrates the additive effects of clothing on static bodydimensions and shows the 95th percentile gloved hand measures.If special items of protective clothing or equipment are involved,the effects shall be measured in positions required by the users



tasks. The effects on the extremes of the population distributionshall be determined.

Discussion. Nude dimension and light clothing can beregarded as synonymous for practical purposes.Additional information on the changes in anthropometricmeasurement values imposed by different clothingensembles are found in Johnson, 1984.



Exhibit 14.1.4.7 (continued) Additive effects of clothing on anthropometric measures

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(1996) anthropometry and biomechanics

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