Safety Science 73 (2015) 43–51

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Safety Science

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Ergonomic design of crane cabin interior: The path to improved safety

http://dx.doi.org/10.1016/j.ssci.2014.11.0100925-7535/� 2014 Elsevier Ltd. All rights reserved.

⇑ Corresponding author.E-mail address: vspasojevic@mas.bg.ac.rs (V.K. Spasojevic Brkic).

V.K. Spasojevic Brkic a,⇑, M.M. Klarin b, A.Dj. Brkic c

a University of Belgrade, Faculty of Mechanical Engineering, Industrial Engineering Department, Kraljice Marije 16, Belgrade, Serbiab Technical Faculty Mihajlo Pupin, University of Novi Sad, Zrenjanin, Serbiac University of Belgrade, Innovation Center, Faculty of Mechanical Engineering, Belgrade, Serbia

a r t i c l e i n f o a b s t r a c t

Article history:Received 19 April 2013Received in revised form 5 September 2014Accepted 11 November 2014

Keywords:SafetyCrane operatorsAnthropometryDesign

Many procedures in the development process of crane cabins today are still based on the specific expe-rience of manufacturers and historical guidelines. It is not surprising that they fail to meet the needs of alarge proportion of operators. Accordingly, the need for more objective, theoretically justified and consis-tent models, that will minimize crane operators’ biomechanical and visual problems through anthropo-metric characteristic analysis to improve safety and prevent crane related fatalities and injuries, arises. Inthat aim we firstly identified the critical characteristics of existing crane cabins linked to visibility andposture (seat and armrest problems) using users’ opinions and Pareto analysis. We then collected rarelyavailable data on crane operators in Serbian companies (64 in the first and 10 operators in the controlsample) and proposed methodology for the ergonomic assessment of crane cabins based on drawing-board mannequins and kinematic modeling. The implemented methodology interval estimate obtainsan interior space of 1095 � 1150 � 1865 mm in which is possible to eliminate the critical characteristicsof existing crane cabins. The research results fulfill user needs not satisfied in existing crane cabins andsuggest certain changes to existing standards on the path to improved safety.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

Cranes, mostly mobile, tower or overhead/bridge cranes(Bureau of Labor Statistics, 2013a and 2013b), are a central compo-nent of many construction operations. For decades now the con-struction industry has been considered as one of the mostdangerous among all major industries, being at the very top ofthe list in terms of the number of accidents and fatalities (Imet al., 2009). In 2012 construction industry had the highest numberof fatal work injuries in any industrial sector (Bureau of LaborStatistics, 2013a and 2013b). The reason for that lies in continualchanges of working processes, the usage of many differentresources, poor working conditions, lack of steady employment,and environments involving noise, vibration, dust, handling ofcargo and direct exposure to weather etc. (Pinto et al., 2011).Between 1991 and 2002 there were 7479 fatalities in the construc-tion industry in the United States (Beavers et al., 2006). The Healthand Safety Commission made particular reference to the construc-tion industry’s problems, with two deaths every week and a fatal-ity rate of six people per 100,000 workers (Sertyesilisik et al.,2010). The HSC‘s further study conducted in the UK in 2004 found

that of the 4624 incidents reported during the five year period, 861occurred during a lifting operation (Sertyesilisik et al., 2010) whilecranes are involved in up to one-third of all construction and main-tenance fatalities (Neitzel et al., 2001).

The construction industry is followed by the transportation andwarehousing industry sectors and then manufacturing, whilefinancial, information and utilities activities record the lowest ratesof deaths and injuries (Bureau of Labor Statistics, 2013a and2013b). According to Yow et al. (2000) mobile cranes (73%) andbridge cranes (16%) are involved in most accidents.

Given the size and power of available cranes, the potential forloss of property and life involved in utilizing cranes without properplanning and safety procedures is tremendous. A tipped, dropped,or mishandled load can directly injure workers or even potentiallyupset a critical section of the construction project, possibly result-ing in the collapse of the structure itself. This risk of loss is not lim-ited only to those directly involved in construction operations,since there have also been many accidents in which pedestrianswere the victims (Neitzel et al., 2001). Construction accidents alsoobviously have huge cost implications (Lee et al., 2006a, 2006b),while other sectors are not negligible, too.

According to Suruda et al. study (1997) of 502 crane-relatedfatalities, the leading causes of death in crane operations areelectrocution (39%), crane assembly/dismantling (12%), boom

44 V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51

buckling/collapse (8%), crane upset/overturn (7%), rigging failure(7%), overloading (4%), struck by moving load (4%), accidentsrelated to manlifts (4%), and working within the counterweightswing radius (3%). The subjective opinions of 86% of general siteemployees show that a crane is the most dangerous piece of equip-ment found on sites while human error is estimated as the biggestcause of accidents (Beavers et al., 2006). Japan, a country with avery good organizational culture, recorded 41 fatalities resultingfrom crane accidents in 2006 alone (Tam and Fung, 2011) whilethe lack of training usually is not the primary cause of fatalities(Yow et al., 2000).

Crane fatalities are not ‘freak occurrences’; they are both pre-dictable and preventable while the massive loss of human life isunnecessary (Shepherd et al., 2000). Neitzel et al. (2001) high-lighted the need for crane manufacturers to design cranes capableof being safely operated, meeting all applicable safety and designstandards, with good maintainability features, and whose typicalhuman factors problem areas should be resolved. The increasedtechnical quality of cranes is the main reason why scenarios suchas ‘crane instability’, ‘jib instability’ and ‘hoisting equipment insta-bility’ contribute less to accidents today (Swuste, 2013). Accordingto the Bureau of Labor Statistics (2013a and 2013b), 51% of workersdied from unknown causes, indicating possible human factorsproblems. Also, crane operators remain in cabins for the wholeday. Tight construction schedules usually hinder the implementa-tion of construction site safety (Mohamed, 2002). The space withinthe cabins is sufficient for only 18.5% of operators, while 28.9% ofthem feel extremely uncomfortable (Tam and Fung, 2011).Although previous research demonstrated that 42% of all incidentsare linked to the design for safety concept (Gambatese et al., 2008),very little research has been done in the field of the assessment ofthe anthropometric convenience of crane cabins. The importanceof studying this problem greatly exceeds the attention devoted toit in previous research studies in this area.

1.1. Objectives and scope of the study

The high rates of construction injuries and fatalities associatedwith cranes clearly indicate that current design and safety proce-dures and devices are not effective enough in preventing accidents(Neitzel et al., 2001), pointing to the need for more objective, the-oretically justified and consistent models. Relevant body measuresare influential in determining numerous aspects of physical inter-actions between users and products (HFES 300 Committee, 2004),so if a product is to be successful in meeting the needs of certainuser group, product designers must use specific information aboutthat user group. This paper aims to define new procedures in thecrane cabin development process and to facilitate interactionbetween operators and cabins by using information on user needsand the collected anthropometric data from Elektroprivreda Srbijehydropower plants, which are undergoing revitalization and recon-struction over the last few years.

This paper focuses on the following objectives: (i) to identifyuser needs through the critical characteristics of existing cranecabins according to users’ opinions using Pareto analysis; (ii) topropose methodology for the ergonomic assessment of crane cab-ins; (iii) to examine and verify the results of such ergonomicassessment; and (iv) to give recommendations for improvingsafety performance related to ergonomical crane cabin design.

This paper empirically tests 23 crane cabin types and is basedon the anthropometric data of 74 crane operators. After the intro-duction in Section 1, Section 2 gives the literature review. Section 3presents the ergonomic design of the crane cabin methodology andresults. Section 4 gives the discussion with recommendation forfuture design, while Section 5 presents the conclusions.

2. Review of the literature

The safety issues pertaining to cranes are described in detail inthe introduction, so herein we will deal with issues connected toergonomics. Literature in the ergonomics field is very narrow; allsurveys with the exception of Ray and Tewari (2012) and Nordinand Olson (2008) are in other fields only touching physiologicalissues.

Chandler (2001) prepared guidelines covering all standards foroverhead crane cabins in the aim to help in reduction of the poten-tial for human error due to design and thus connecting ergonomicsand safety issues. His main aim was to aid human factors engineersin evaluating existing cranes during accident investigations orsafety reviews.

Sen and Das (2000) analyzed the cabins and hooks in 51 electricoverhead travelling cranes in a heavy engineering factory andnoticed that control-movement compatibility was absent in mostof the cranes, making the operators’ job even harder. Crane opera-tors also frequently control more than one crane per shift andincompatibility makes their job more stressful.

Operating a crane demands a static sedentary position withhands held steady on the operating handles with frequent bodytwisting, deep sideways bandings and exposure to vibrations thatare risk factor for lower back pain. Beavers et al. (2006) highlightedthe problems with the seat, visibility, noise, commands, access tothe cabin etc., but did not analyze them further. Burdorf andZondervan (1990) carried out a survey among 33 crane operatorsin a steel factory and recommended persons with a history of backcomplaints not to seek employment as crane operators. On a sam-ple consisting of 46 crane operators Bovenzi et al. (2002) found that40–60% of operators with 12-month prevalence have lower backpain. Kittusamy and Buchholz (2004) also concluded that awkwardposture during the operation of heavy construction equipment is aconsequence of improper cab design and work procedures, empha-sizing poor visibility of the task, limited room in the cab, excessiveforce required to operate levers/pedals, and improper seat designs,as some of the characteristics of a poorly designed cab.

Tall crane operators are probably the most vulnerable workers.Carragee et al. (2008) synthesized the literature and presented thefact that among workers in manual occupations, the annual prev-alence of neck pain varied from 16.5% in spinning industry produc-tion line workers in Lithuania to 74% in Swedish crane operators,who are among the tallest in Europe.

All previously discussed surveys do not include any anthropo-metric analysis.

Knowledge of human anthropometric characteristics is a prere-quisite for a good understanding of the fit between man andmachine and for the biomechanical design of any work system,too (Hsiao and Keyserling, 1990). One of the surveys in the narrowfield of this paper carried out by Ray and Tewari (2012) studied 23body dimensions of 21 crane operators in order to minimize theanthropometric mismatch within the enclosed workspace. Theyfound many misfits of even the 50th percentile crane operator pop-ulation on site with the existing work system (Ray and Tewari,2012). Using the example of the crane cabin manufactured byMacGREGOR which operates in Sweden, Nordin and Olson (2008)discussed crane operators’ comfort and reached the conclusion thatthe given cabin was not suitable for the majority of the population.

Unfortunately, many procedures in the development process ofcrane cabins are still based on the specific experience of manufac-turers and historical guidelines that are often arbitrary and subjec-tive, hence the need for new objective, theoretically justified andconsistent models.

Previous research points out the need to increase the well-beingand facilitate the interaction of crane operators to eliminate

V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51 45

discomfort and consequently accidents at work through anthropo-metric characteristics analysis. This would serve to improve safetyand prevent crane related fatalities and injuries.

3. The ergonomic design of the crane cabin interior:methodology and results

We will start the ergonomic design of the crane cabin interiorfrom user needs analysis on Nordin and Olson (2008) data on 6cabin types in Sweden followed by a new sample of 17 cabin typesin Serbia in order to find the critical characteristics of existingcrane cabins. The collected anthropometric data on a sample con-sisting of 64 crane operators then will be used to comfortablyaccommodate the highest possible range of anthropometric mea-surements between the 5th and 95th percentiles of crane opera-tors, through methodology based on mechanical mechanisms tofulfill user needs not satisfied in existing crane cabins. The secondsample containing 10 new crane operators from Serbia will serveto prove our methodology and provide recommendations fordesigners. The methodology is shown in the flow chart in Fig. 1.

3.1. The critical characteristics of existing crane cabins

In order to improve working conditions for crane operators, it isnecessary to determine the goals and criteria for the improvementof contemporary crane cabins first. Benchmarking is the methodthat enables organizations to identify the key processes/character-istics that need improvement (Fernandez et al., 2001). Understand-ing user voice and enhancing design characteristics to meet userrequirements increases product competitiveness as the challengefacing designers (Lin et al., 2008). Benchmarking analysis for cranecabins is very rare in the available literature, and one of the fewwas performed by Nordin and Olson (2008), but without Paretoanalysis to identify important problems. Since the assessment

Fig. 1. Design and evaluation methodology for crane cabin.

criteria are not the same for all characteristics in accordance withthe benchmarking analysis, the assessment in this survey is per-formed by modifying the data on needs weighting (from 1 to 5)provided in Nordin and Olson (2008) in percentage indexes withthe aim of harmonizing the criteria and their subsequent analysis.The results of our analysis of the modified Nordin and Olson (2008)data of six crane manufacturers indicate that through the averagepercentage index of needs fulfilled the placement of indicators andregulators (index 0.4) poses the biggest problem, followed by dis-play content visibility (0.5), the problems of work posture andunderstandability of signalization which are of equal importance(index 0.533), understandability of symbols (index 0.542), as wellas the problem of load visibility (index 0.6). Further Pareto analysisof the identified problems indicates that the given characteristicsaccount all the main causes of problems in crane operators’ work.

The problems identified in our analysis of the Nordin and Olson(2008) data show that international crane cabin manufacturersneed to improve designs to make indexes closer to the desiredvalue that amounts 1. Without needs analysis through benchmark-ing, Kittusamy et al. (2004) also concluded that exposure to work-related musculoskeletal disorder risk factors stems from the inter-face between the design of the equipment and cab interior (e.g. thelocation of the controls, windows, and mirrors) and the task char-acteristics (e.g. the duration of the task, the location of the task thatdictates the viewing angle). Thus, the design of the cab interiorinfluences the awkward postures of the joints, whereas the longduration of the task impacts on the static exposure to awkwardpostures as well as long-term exposure to whole-body vibration.

In that aim Kittusamy (2003) introduced a checklist for evaluat-ing construction equipment cab design that provides a static,instantaneous snapshot of characteristics during a specific timeand provides the critical point of initial ergonomic analysis (moredetailed than that given in Nordin and Olson, 2008. The contentof Kittusamy’s list and its capacity for assessing errors in cabindesign make it a suitable reference tool for the assessment ofdesigner solutions in cranes and heavy mobile equipment (scrap-ers, dozers, backhoes, and loaders). A data check-list with 32 ques-tions was applied to 17 types of crane cabins located in Serbiamanufactured by domestic and international producers and theiroperators filled it (17 persons from our larger sample were willingto complete the list and give interviews). The negative percentageindex was calculated on the data collected in Serbia so as to showthe percentage of possible improvements according to the param-eters defined by the questionnaire. Kittusamy and Spokane (2003)proposed overall total cab score calculation on the collected data tocompare producers, but not to identify the top portion of causesthat need to be addressed so as to resolve the majority of problems.Therefore, in this survey Pareto analysis was performed for the lat-ter in order to show what causes the majority of problems. Resultsshow that the largest part of problems is caused by armrests(13.6%), starting from whether they are available at all, and, if so,whether they are placed at an appropriate height and whether theyare adjustable. Then follow the problems of vertical and horizontalseat adjustability (12.8%). The negative index ranging from 10% to12% includes questions referring to the lumbar support of the seat,whether it can be tilted backward and whether it can swivel. Thiscategory also comprises temperature control by the operator. Thenegative index value from 5.5% to 10% includes problems such aswhether the seat has initially been set at an appropriate height,whether the controls or levers are easily reachable and easily oper-ated, whether there is sufficient upward visibility and if the view ofthe operation is obstructed, whether the general overview of theground zone is good and whether there are distracting reflectionsfrom the cabin windows.

The results of the needs analysis on the samples of crane cabinsoperating in Sweden and Serbia indicate the need to conduct

Fig. 3. Hip width (mean value in mm) for the crane operator age groups.

46 V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51

further ergonomic analyses using anthropometric measurements,especially when we bear in mind the fact that tall crane operatorsare probably the most vulnerable workers (Carragee et al., 2008). Itshould be particularly emphasized that the Swedish populationhas the largest average height and Serbs follow in the Europeanregion.

3.2. The anthropometric accommodation of crane operators:workspace modeling

A well-designed crane cab not only makes a significant differ-ence to the operator’s working conditions, but also affects thesafety on sites where cranes operate. Today there is a pressing needto enhance ergonomic cab designs for safe and efficient operationdue to high incident rates that are the logical consequence of theunresolved ergonomics problems as our survey has shown.Up-to-date anthropometric data play a key role in their design.Unfortunately, although Pareto analysis in the previous sectionhas shown that the critical characteristics of cabins are notappropriately designed, anthropometric data on the crane operatorpopulation have rarely been collected in the past.

Our aim, by limiting the interior space, is to accommodate thehighest possible range of crane operators’ anthropometric mea-surements between the 5th and 95th percentiles (as the tradi-tional, most widely used design criterion and economical choiceaccording to Helander, 2006) so that they have both comfort andsafety when operating the crane. According to Klarin et al. (2009and 2011), with certain adjustments, 99th percentiles can also beaccommodated in that interior space (as shown in Fig. 3). As pro-posed by Vogt et al. (2005) and proved in our survey, the Klarinet al. (2009) concept, with fixed heel point, is closest to commonseating concepts and economically justified in all designs wherefoot controls exist. Since crane drivers also use foot controls, themain hypotheses of this research are:

H1. The crane operator and the cabin form a system withnumerous interactions, whose origin of the coordinate system, asthe starting point for dimensioning and construction, is the fixedpoint of the crane operator‘s heel on the cabin floor behind the footpedal.

H2. Other dimensions important for dimensioning the crane cabinare further determined by the movement of anthropometric mea-surements according to the kinematic mechanism principles.

The profession of a crane operator is quite specific and requiresspecial selection and training. The share of crane operators in thegeneral Serbian population is quite low. Hence, our first samplecomprised 64 participants. All participants were male, with anaverage age of 47.64, with standard deviation of 10.34 years.

Fig. 2. Stature (mean value in mm) for the crane operator age groups.

Measurements were taken in several Elektroprivreda Srbije hydro-power plants located throughout Serbia, where a large number ofcranes are stationed (types common for both construction andindustrial sites: overhead/bridge, mobile, tower, and gantry craneswith cabins). Elektroprivreda Srbije hydropower plants haveundergone revitalization and reconstruction over the last fewyears, executing both construction and other industrial works.Accordingly, these sample characteristics ensure the intended rep-resentativeness. The sample was formed by means of the staticanthropometry method, which implies measuring in the erectposition during standing and sitting (so that the torso is at a 90�angle with the upper leg, and the upper leg at a 90� angle withthe lower leg). As can be seen in Table 1, a total of 9 basic staticanthropometric dimensions including weight were recorded foreach individual: Stature (mm), Seat height (mm), Upper leg height(mm), Lower leg height (mm), Shoulder breadth (mm), Hip breadth(mm), Arm length (mm) and Shoe length (mm). Shoe length waschosen due to the fact that operators use pedal controls in shoes.The standard anthropometric instruments used in this study werean anthropometer, a beam caliper, sliding calipers, and steel tape.Other instruments included a weight scale and a stool for seatedmeasurement. The participants remained in their clothes andshoes during the measurement. To ensure data quality, we trained3 measurers prior to data collection (inter-rater variations minimi-zation) and the measuring team repeated the measurements onparticipants until the inter-observer differences were at or belowthe levels specified in Gordon and Bradtmiller (1992).

Table 2 illustrates the correlation coefficients obtained betweenthe analyzed dimensions. Approximately 60% of the correlationcoefficient values obtained are significant at the 5% level, whilethe remainder are non-significant. The highest correlation coeffi-cients were found between stature, lower and upper leg heights,and seat heights as well as between hip width and BMI, which isa more appropriate measure then weight.

Figs. 2 and 3 illustrate the average values obtained for two dif-ferent anthropometric dimensions according to the defined agegroups. These show that dimensions vary significantly with age,and, as can be seen, crane operators lose height and gain moreweight over the years. It is also interesting to compare these resultswith other anthropometric data in Serbia (only our surveys aboutcar drivers are available) which show that the hip width of the95th percentile car driver in Serbia is significantly lower and hasan average value of 420 mm (Klarin et al., 2008) compared to491.4 mm value in crane operators. That is probably caused bythe nature of the crane operator’s job which involves long periodsof sitting. In addition, the seat height of car drivers in the rangebetween the 5th and 95th percentiles is 852–994 mm, while forcrane operators it is 806–981 mm. This ratio for the shoulderbreadth of car drivers is 403–534 mm, and for crane operators391–543 mm.

Table 1Standard deviation (SD) and percentiles for the anthropometric dimensions of the crane operators (n = 64).

Dimension Shoe length(mm)

Weight(kg)

Stature(mm)

Sitting height(mm)

Lower leg height(mm)

Upper leg height(mm)

Shoulderbreadth (mm)

Hip width(mm)

Arm length(mm)

Standard deviation 8.9 11.65 59.47 53.25 30.028 38.14 46.16 59.83 45.325th percentile 249.4 65.3 1650 806 529.7 551.4 391.75 295.2 615.450th percentile 264 84 1750 890 580 610 470 390 69095th percentile 278.6 103.75 1847.8 980.5 628.2 677.5 543.16 491.4 764.0599th percentile 284.7 111.54 1888.8 1017.27 648.9 702.8 575 532.6 795.3

Table 2Matrix of the Pearson correlation coefficients obtained between the anthropometric dimensions analyzed (a bold indicates that the value is significant at the 0.05 level).

Variable Stature(mm)

Sitting height(mm)

Lower legheight (mm)

Upper legheight (mm)

Shoulderbreadth (mm)

Hip width(mm)

Arm length(mm)

Shoe length(mm)

BMIkg/m2

Stature (mm) 1.000 0.7468 0.3170 0.2988 �0.0004 �0.1659 0.4878 0.4846 �0.1253P = – P = 0.000 P = 0.011 P = 0.016 P = 0.997 P = 0.190 P = 0.000 P = 0.000 P = 0.324

Sitting height (mm) 0.7468 1.000 0.1649 0.1176 �0.2080 �0.5235 0.7468 0.2630 �0.3911P = 0.000 P = – P = 0.193 P = 0.355 P = 0.099 P = 0.000 P = 0.000 P = 0.036 P = 0.001

Lower leg height (mm) 0.3710 0.1649 1.000 0.7867 0.4056 0.2901 0.5256 0.2513 0.27358P = 0.011 P = 0.193 P = – P = 0.000 P = 0.001 P = 0.020 P = 0.000 P = 0.045 P = 0.029

Upper leg height (mm) �0.0004 0.1176 0.7867 1.000 0.4500 0.3791 0.4063 0.2445 0.3671P = 0.997 P = 0.355 P = 0.000 P = – P = 0.000 P = 0.002 P = 0.001 P = 0.051 P = 0.003

Shoulder breadth (mm) �0.1659 �0.2080 0.4056 0.4500 1.000 0.7904 0.0644 �0.0522 0.5857P = 0.190 P = 0.099 P = 0.001 P = 0.000 P = – P = 0.000 P = 0.613 P = 0.682 P = 0.000

Hip width (mm) �0.1659 �0.5235 0.2901 0.3791 0.7904 1.000 �0.1797 0.0052 0.7495P = 0.190 P = 0.000 P = 0.020 P = 0.002 P = 0.000 P = – P = 0.155 P = 0.967 P = 0.000

Arm length (mm) 0.4874 0.5551 0.5256 0.4063 0.0644 �0.1789 1.000 0.1522 �0.0103P = 0.000 P = 0.000 P = 0.000 P = 0.001 P = 0.613 P = 0.155 P = – P = 0.230 P = 0.936

Shoe length (mm) 0.4846 0.2630 0.2513 0.2455 �0.0522 0.0052 0.2498 1.000 0.1130P = 0.001 P = 0.036 P = 0.045 P = 0.051 P = 0.682 P = 0.967 P = 0.047 P = – P = 0.374

BMI kg/m2 �0.1253 �0.3911 0.2735 0.3671 0.5857 0.7495 �0.0103 0.1130 1.000P = 0.324 P = 0.001 P = 0.029 P = 0.003 P = 0.000 P = 0.000 P = 0.936 P = 0.374 P = –

V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51 47

We have already applied the methodology of workspace model-ing in car driver interior space design in Klarin et al. (2011) whichis similar to that described in Hamza et al. (2004). The modeling ofthe cab construction starts by adjusting the elements of thehuman-cabin system to comfort posture, along with fixing the ori-gin of the coordinate system. Vogt et al. (2005) suggested fixing thejoint visual angle or operator’s hip for the heel, hip or hand. Allnon-fixed body points generate an accumulation of points wherebya field is defined. The crane cab requires the construction measuredin the coordinate system with the fixed point in the operator’s heel,which is in front of the foot pedal. Fixing the zero coordinate pointis enabled by the kinematics of heel movement, as shown in Fig. 4,which for large legs and feet, due to seat movement backwards anddownwards, moves the heel relatively toward the front along withan increase in the foot’s angle with the floor (command). In the

Fig. 4. Heel point (a) and foot movement (b) of

opposite case, this is achieved by moving the heel, e.g. in smallanthropometric measurements, toward the back and reducingthe angle between the foot and the floor, along with an increasein the angle between the lower and the upper leg, as well asbetween the upper leg and the seat height (torso), all aimed atthe maximum overlapping of visual angles for 5th to 95th percen-tile males.

Hence, our dimensioning methodology has three basic postu-lates based on functional anthropometry, which is task oriented:

1. The construction and dimensioning of the cabin start from theorigin of the coordinate system at the fixed point of contactbetween the crane operator’s heel and cabin floor in front ofthe foot pedal next to the right foot, as already used in othersurveys that also use pedal controls.

5th – percentile and 95th – percentile man.

Fig. 5. Pattern of body segments for drawing-board manikin.

Fig. 6. Recommended seating space

48 V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51

2. The visual angles for the whole predicted range of operatorswith the criterion of the smallest possible deviation cannot bethe same, but they are dimensioned to the minimum of 60�,because the downward viewing angle is about 60� below thehorizontal line (Anshel, 2002 and Nemeth, 2004).

3. The remaining space is dimensioned in line with large anthro-pometric measurements ranging from 5th to 95th percentileoperators, corresponding to the movement of a mechanicalmechanism, i.e. complying with the kinematics of movement,which is described in detail in Klarin et al. (2011).

Drawing-board mannequins are used to estimate the best worklocation for a given task (as proposed in Armstrong et al., 1986).Using the pattern of body segments, shown in Fig. 5 for thedrawing-board mannequin, as well as the data from Tables 1 and2, we were able to obtain a vertical projection (in the z–x plane)of the space necessary for placing the crane operator in the cabinthrough kinematic modeling, as shown in Fig. 6.

Fig. 6 shows that the visual angle of 60� when lookingdownwards is possible for the range of the 5th to the 95th percen-tile operators, which overlaps in two extreme positions, where thehip joint angle for the 5th percentile is 87� while for the 95thpercentile angle amounts 104�. According to Nemeth (2004) thenormal human visual field extends to approximately 60�, so thereis no impact on the neck. The optimal angle of the seat surface has

for crane operators (side view).

Fig. 7. Recommended seating space for crane operators (top view).

V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51 49

been enabled in all positions, so that the femur is horizontal, andthe hip and the seat surface form an angle of 7�. The arm spanfor using manual commands for both positions of the 95th percen-tile operator, in accordance with the head position and movement,horizontal and vertical seat adjustment and other dimensions andangles, from the shoulder joint (semi-center of rotation) to thehand with folded fingers is 764 mm. For the 5th-percentile opera-tor who is in position III with reach 3, the arm span is 616 mm, butthe part of the field shaded in Fig. 6 cannot be used in this casesince it is outside the haptic field of the 95th-percentile operator.The arm flexibility of the 5th percentile operator enables normalwork and use of commands within the reduced field. The chairshould be adjustable 200 mm horizontally and 100 mm vertically.The minimum total height of the interior and cabin door should beequal to the stature of the 95th percentile operator in shoes withclothes (Bridger, 2008), e.g. 1850 mm in order for comfortableentry into the cabin. Further headroom space is not consideredbecause operators work in a sitting position. The length of theseating surface of 400 mm and the height of the backrest aredetermined by the anthropometric measurements of the 5thpercentile operator.

In the z–y plane, the y-axis dimensions are determined by theshoulder and hip breadth and arm and leg haptic fields. The shoul-der breadth for the 5th percentile operator is 391 mm, and 543 mmfor the 95th (according to Table 1). The hip breadth for the 5th per-centile operator is 290 mm, and 490 mm for the 95th percentileoperator, which is significantly higher than the average for the Ser-bian population or other professions. The seat height should bevertically adjustable from 625 mm to 735 mm, implying a rangeof 110 mm, with the horizontal movement of 50 mm. The problemof the armrest height is reduced to a compromise between therequirements of standard ergonomics and the need to use bothhands simultaneously. The ergonomics of arm movements duringwork requires the placement of the work object in the optimal hap-tic field, which means that the field at elbow height with the upperarms hanging loosely next to the body, while the angle betweenthe lower arm and the upper leg is 90�, while forming arches inthe horizontal plane of the left and right arm. The intersection ofthe fields of both arches directed toward the body is the optimalhaptic field. Since in this case the position of the commands wouldobstruct the visual angle they need to be separated into consoles,which also serve as armrests. The armrest and the seat should beadjustable, both in terms of height (z-axis) and length (x-axis).The position of the backrest with the commands is restricted bythe maximum arm span, bearing in mind that the field withinthe optimal visible visual angle of 60� should be discarded. Thenext restriction refers to the depth of the chest of the 5th percentileoperator, and hence the command should have a vertical axis onthe straight line x = 200 mm. The backrest position in relation tothe seat surface is the result of two movements: movement dueto differences in seating height and owing to the difference inthe height of the bent elbow for 5th and 95th percentile operators.Hence, the two final positions of the backrest separated by 210 mmare obtained and marked by the thick line in Fig. 6. The samemethod was used to obtain the basic dimensions of the crane oper-ator’s work chair in the x–y plane, shown in Fig. 7.

The final minimum interior space crane cabin dimensions,based on normal operational requirements and adequate roomfor operator comfort and safety according to anthropometric mea-surements in Serbia, were obtained as projections of 5th and 95thpercentile mannequins on the x, y and z axes in Figs. 6 and 7.According to the point estimate, the dimensions of the enclosurespace (interior space for the comfortable work of crane operator)amount to 1080 � 1100 � 1850 mm. Using interval estimates andwhen rounded up to integer numbers the space dimensions are1095 � 1150 � 1865 mm.

A system of mounted cameras and visual display units maysolve obstruction problems which interfere a clear view of the taskand cause poor visibility in certain operator fields (Wilson, 1995),since the already maximized visual angles still have obstructions.As proposed by Lee et al. (2006a, 2006b) a video camera could beinstalled on the crane and a device developed to transmit visualsignals to a monitor installed in the operator’s cab on the crane,or cutting-edge wireless video control, RFID and GPS technologycould be introduced. The operator would be able then to controlthe picture on a color LCD monitor and navigate through differentzoom modes as required (Yang et al., 2011). Shortening individualcycles due to a better vision system ultimately adds up to a shorterworking time for the crane and shorter delays caused by the denialof crane service to noncritical activities (Yang et al., 2011). Byallowing the crane operator to continuously view the theater ofwork, the system prevents accidents and enhances work safety,while night shifts are possible, too. Signalmen are no longer neces-sary either. The proposed solutions require space in the cabins’right angle with three degrees of freedom, which enables all move-ments such as vertical, horizontal, and rotation to match the oper-ator’s diverse physical positions when using cameras/displaysystem.

3.3. Results validation

The second sample data of 10 crane cabin operators given inTable 3 were collected in Serbia in 2013 using the same methodas for the first one, to serve for modelling verification.

The operators from the control sample could be placed in thefirst sample’s enclosure space and all the participants in the controlsample were found to be within the space limits. In that way, theused methodology is validated.

Finally, it was also proved that a satisfactory working environ-ment and greater employee safety for crane operators can beachieved after the proposed ergonomic adaptation.

4. Discussion

The most frequently used recommendations from availablestandards and manufacturers’ arbitrary historical guidelinesshould be partially modified in keeping with the findings of this

Table 3Anthropometric dimensions for 10 crane cabin operators – the second sample.

Measurement Shoe length(mm)

Stature(mm)

Sittingheight (mm)

Lower legheight (mm)

Upper leglength (mm)

Shoulderwidth (mm)

Hip width(mm)

Arm length(mm)

1. 284 1850 980 610 640 490 430 7502. 284 1850 990 590 670 530 500 7503. 283 1730 980 580 650 520 460 7004. 287 1750 980 620 650 540 500 7505. 283 1760 840 590 580 500 400 7306. 283 1760 920 580 600 500 370 7207. 267 1775 909 580 625 445 375 7108. 257 1820 958 580 630 485 410 7009. 283 1770 970 620 640 540 410 770

10. 283 1760 950 600 650 550 400 790

50 V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51

research in order to increase the operator’s comfort in the follow-ing way:

� There is a change in the range of the seat height adjustmentupwards and downwards from 152.4 mm (according toChandler, 2001, to improve crane cabins used in Boing) to100 mm in this survey, while the increment remains no morethan 30 mm. Producers of ergonomically adapted crane cabinssuch as Brieda, however, have a range of 90 mm (from532.5 mm to 627.5 mm).� The seat width should range from 450 mm to 510 mm, as pro-

posed in ISO 8566-5 (1992), which according to our results,has an exact value of 490 mm.� The seat length is not in accordance with ISO 8566-5 (1992),

and this survey comes to a result of 400 mm.� The seat should have waterfall edges (this recommendation

remains as given in Chandler, 2001).� The seat should slope backward from 0� to 7� (it should not be

fixed at 7� as given in ISO 8566-5 (1992)).� The original backrest size was 381 to 508 mm high according to

ISO 8566-5 (1992), while the results now demand 550 mm. Thewidth of 300 mm to 360 mm, according to ISO 8566-5 (1992)should be increased to 380 mm. A width of 380 mm enablesmaximum torso mobility and movement greater than 180�when required.� The seat should have five supporting legs or be attached to the

cab floor and provide adjustable seat positioning toward theconsole. The swivel chair with supporting legs should have aseat base of 457 mm (this recommendation remains as givenin Chandler, 2001).� The armrests should be undercut to allow enough space for the

hips and thighs.� The armrests should be adjustable in the range between

220 mm and 280 mm instead of the previous 190 mm and297 mm according to ISO 8566-5 (1992).� The armrests should be 120 mm to 200 mm in length instead of

the recommended 203 mm according to ISO 8566-5 (1992).

Our sample was considerably larger than all of the samples usedso far. Burdorf and Zondervan (1990) used a sample of 33 partici-pants, Bovenzi et al. (2002) of 46, and Ray and Tewari (2012) 21. Ifwe compare this data to available research in the field, the meanand standard deviation values for the height of crane operatorsin Serbia of 1750.30 and 59 mm in the first and 1782 and42.25 mm in the second sample or 1754.65 and 58.27 mm for both,are close to the values of 1765 and 74 mm obtained by Burdorf andZondervan (1990) on a smaller data sample in the Netherlands, andto those of 1780 and 68 mm gained by Bovenzi et al. (2002) also ona smaller set of data in Italy.

The methodology applied on the sample of Serbian crane oper-ators may serve to eliminate the critical characteristics of existing

crane cabs obtained through Pareto analysis (the majority of prob-lems are caused by armrests, seat adjustability, seat lumbar sup-port, the reachability of controls or levers, and visibility). Thenew cab construction makes it possible to have adjustable arm-rests placed at an appropriate height (according to our survey,the existing cabs had the highest negative index of 13.6%). The seatproblems have also been resolved in terms of both height andwidth (a negative index of 12.8%). It is also necessary to provideseat lumbar support, the option of swiveling and turning (a nega-tive index of 10–12%), as well as the ability to control the cab tem-perature. In addition to enabling the largest possible visual angle,load visibility problems should also be solved by setting up a sys-tem of monitors and cameras, which can be initiated by the oper-ator when the load is outside his visual field. Usage of transparentmaterial for most of the lateral parts of the cabin and a significantpart of the floor ceiling is recommended in order to improve theoperator’s visibility when the vision system is not in use. The visionsystem, when implemented, can allow the operator to observe theresults of the tasks he is controlling and enable him to make cor-rect decisions based on accurate information perceived, withoutturning the head to the left or right more than 30�, i.e. tilting thehead more than 5� up and more than 25� down (Barron et al.,2005). In Dondur et al. (2012) the economic feasibility of the pro-duction and use of new generation crane cabins with the problemof visibility solved through video control was already analyzed.Such cranes will allow higher productivity due to the reductionof the physical and psychological stress of the operator, as wellas greater safety and security thanks to the integrated visual sys-tem. Dondur et al. (2012) also proved that the total economic ben-efit of the exploitation of the cabin in the overall exploitationperiod is significantly higher than the purchase price – the internalrate of return is above the relevant weighted average interest rateand the payback period is less than three years, so the project fitsinto the very low risk category. All previously mentioned designsolutions are expected to solve the problems identified by theoperators in this survey thus improving the critical characteristicsof crane cabs and impacting positively on safety.

5. Conclusions

Despite being the cause of large numbers of accidents, cranecabins today are not designed in accordance with operators’anthropometrics. Therefore, the starting point in this paper is thedata gathered about the anthropometrics of the operator samplewhich significantly differ from the data of the general population.Research into the operators’ needs then follows in order to identifythe significant problems by means of Pareto analysis. Later, a num-ber of problems, such as how to minimize or remove the anthropo-metric mismatch, how to enhance the workspace visibility for acrane cabin operator in an enclosed workspace, and how to

V.K. Spasojevic Brkic et al. / Safety Science 73 (2015) 43–51 51

improve work posture thus minimizing the risk of musculoskeletaldisorders by applying ergonomic principles, have been solvedthrough modeling crane operator workspace. The usefulness ofthe methodology used in addressing and solving these problemsand the quality of the solutions obtained are verified on the secondsample of crane operators. All operators from the second sampleare accommodated in the proposed interior space of1095 � 1150 � 1865 mm thus validating the methodology. Themethodology is expected to be used in the future on new samplesof crane operators in different geographical regions so as to con-firm our expectation that shorter persons are accommodated moreeasily. Also, the application of our recommendations in designshould have a number of benefits, such as the increased enthusi-asm of crane operators, a reduction in work-related pain and injuryrisk, an increase in the comfort and efficiency of crane operators,and an increase in overall system productivity and safety.

It is also possible to use the procedure implemented in thisresearch study for modeling other professions.

The existing cabs were evaluated from the operators’ spacerequirements and their field of vision, while further investigationsshould be made in order to test noise, vibrations, luminance, tem-perature and air humidity. Controls also give sufficient room forfuture research.

There is also a need for extensive surveys focusing on both maleand female crane operators in different regions in order to generateregion specific anthropometric databases for the further safe andefficient design/modification of crane cabins with harmonizingall collected data.

The percentiles are univariate (one-dimensional) statisticsapplied to multivariate situations, so future research could alsodeal with that fact and apply multivariate statistics.

Acknowledgments

This work is supported by a grant from the Eureka E!6761 andTR 35017 projects. We would also like to thank Prof. Pradip KumarRay for his useful comments and recommendations.

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