A Checklist for Evaluating Cab Design 

of Construction Equipment 

Reported by N. Kumar Kittusamy 

Awkward postures during the operation of heavy construction equipment 

are a consequence of improper cab design and work procedures. Poor visibility of the task, limited room in the 

cab, excessive forces required to operate 

levers/pedals, and improper seat designs 

are some of the characteristics of a poorly 

designed cab. If not controlled, awkward 

posture of any body part can result in increased risk of fatigue, pain, or injury. 

Exposure to awkward postures, either 

repetitively or for prolonged periods, 

can lead to a variety of musculoskeletal 

disorders. 

Laboratory studies have shown that 

non-neutral trunk postures (i.e., flexion, 

lateral bending, and/or twisting) caused 

increased levels of muscle fatigue and 

intervertebral disc pressure in the lower 

back.(1) Epidemiological studies have 

shown that flexion, lateral bending, and 

twisting of the trunk are factors in the development of low back pain.(2,3) Spinal 

disc compression can increase substantially when the trunk changes from a 

neutral to a flexed posture.(4) Furthermore, prolonged sitting can also result in an increased risk of low back 

pain.(5) 

Laboratory studies of non-neutral 

shoulder postures have shown that prolonged elevation of the arms (abduction or flexion of the shoulder) causes 

extreme levels of muscle fatigue and 

discomfort.(1,6) Hagberg(7) demonstrated 

a positive relationship between shoulder 

elevation and increased risk of tendonitis 

in a cross-sectional field study. A relationship between non-neutral neck posture and the development of disorders 

has also been well documented.(8) 

The objective of this article is to introduce a one-page checklist for evaluating 

cab design of construction equipment. 

The cab design evaluation checklist was 

developed, pilot-tested, and used to measure several characteristics of cab design 

(see Table I). 

TABLE I
 

A checklist for evaluating cab design of construction equipment 

Yes No N/A Comments 

I. Characteristics 

1. Is the seat height adjustable?	 1
 

2. Can the seat be adjusted horizontally?	 2
 

3. Is the seat set at proper height?	 3
 

4. Does the seat have a back support?	 4
 

5. Does the seat have a lumbar support?	 5
 

6. Are there armrests available?	 6
 

7. Are the armrests adjustable?	 7
 

8. Are the armrests set at proper height?	 8
 

9. Do you feel any vibration from the equipment through the seat?	 9
 

10. Do you feel any vibration from the equipment through the	 10
 

floor?
 

11. Do you feel any vibration from the equipment through the	 11
 

controls?
 

12. Is the seat firmly mounted to the floor of the cab?	 12
 

13. Can the seat be tilted backward?	 13
 

14. Can the seat swivel?	 14
 

15. Is the location of the controls or levers adjustable?	 15
 

16. Can you easily reach the levers or controls?	 16
 

17. Can you easily operate the levers or controls?	 17
 

18. Can you easily reach the pedals?	 18
 

19. Can you easily operate the pedals?	 19
 

20. Is the cab area large enough (e.g., uncramped area) for you?	 20
 

21. Do you have sufficient upward visibility?	 21
 

22. Is your view of the operation obstructed (e.g., cab guards,	 22
 

pipes/hoses, etc.)?
 

23. Do you feel the cab is noisy?	 23
 

24. Can you control the temperature of the cab?	 24
 

25. Does the equipment have steps?	 25
 

26. Does the equipment have handrails?	 26
 

27. Can you easily open/close the cab doors?	 27
 

28. Does the equipment have proper means for entering the cab?	 28
 

29. Does the equipment have proper means for exiting the cab?	 29
 

II. Environmental 

30. Do you have a good general view of the ground?	 30
 

31. Are the cab windows free from distracting reflections?	 31
 

The checklist was based 

on a literature review and was then discussed with the operators of construction 

equipment. The draft checklist was then 

pilot-tested with input solicited from 

and incorporated by trainers, operating 
engineers, and apprentices. A case study 

is presented in which overall cab design 

scores were calculated for each type of 

equipment. 

Case Study 

The checklist was designed to be a 

systematic evaluation tool that could be 

used to assess the characteristics of a 

cab. A majority of the questions in the 

checklist were structured so that satisfactory ergonomic conditions resulted 

in affirmative answers to the questions. 

There were three questions that had to 

be worded in an inverse relationship to 

avoid ambiguity. If supplying a categorical answer was difficult, the answer was 

qualified by an overall assessment of the 

characteristics of concern. 

After the evaluation of the cab design, 

an overall assessment score for the cab 

was calculated. This was done by assigning equal weights to each of the answers, 

and a percentage of affirmative answers 

were determined. The closer the calculation was to 100 percent, the better the design or the acceptability of the cab. Some 

features of the cab may be more important than others, but the simple approach 

of equal weights was considered here as 

used by Lifshitz and Armstrong.(9) 

Equipment and Operators 

Studied 

The study was performed at several 

different construction sites in the Greater 

Boston, Massachusetts area. Seven 

journey-level (experienced) operators 

(6 males and 1 female) employed by two 

major contractors were studied (see Table II). 

TABLE II 

Background data of operators and equipment evaluated in this study 

Characteristics of the operator Equipment information 

OperatorA Height (cm) Weight (kg) Age Years of exp Make Model Size Type 

1 165 52 33 11 Caterpillar CAT 416B Small Loader/Backhoe 

2 178 129 49 30 Caterpillar CAT 446B Small Loader/Backhoe 

3 183 86 38 17 John Deere JD 710D Small Loader/Backhoe 

4 165 70 58 36 Caterpillar CAT M318 Medium Excavator 

5 178 100 56 40 Caterpillar CAT M318 Medium Excavator 

6 168 86 35 15 Daewoo DH 200W Large Excavator 

7 170 66 35 12 Komatsu PC 400LC Large Excavator 

Mean 172.4 84.2 43.4 23.0 

SD 7.1 25.4 10.7 12.1 

Var 50.4 644.6 113.6 145.3 

AOE #1 is a female; all others are male operators. 

The operators’ ages ranged from 

33 to 58 years (43.4 ± 10.7); experience 

ranged from 11 to 40 years (23 ± 12.1); 

height ranged from 165 cm to 183 cm 

(172.4 ± 7.1); and weight ranged from 

52 kg to 129 kg (84.2 ± 25.4). Each operator used a different piece of construction 

equipment. Operators were briefed about 

the study, and they each signed a consent 

form to participate in this research. 

Results 

All seven equipment types listed in 

Table II were evaluated. The overall total 

cab score was calculated using all 31 

questions in the cab design evaluation 

checklist. The results of the overall cab 

design score are summarized in Table III. 

TABLE III 

Evaluation of cab characteristics using the cab design checklist 

Equipment information 

Operator 

Overall total 

cab score Mak A e Model Type 

1 Caterpillar CAT 416B Loader/Backhoe 74 

2 Caterpillar CAT 446B Loader/Backhoe 74 

3 John Deere JD 710D Loader/Backhoe 71 

4 Caterpillar CAT M318 Excavator 87 

5 Caterpillar CAT M318 Excavator 81 

6 Daewoo DH 200W Excavator 81 

7 Komatsu PC 400LC Excavator 71 

AOverall total cab score computed using all questions in the checklist. 

The overall total cab design scores for the 

seven equipment types ranged from 71 to 

87 percent, with a 6.5-percent standard 

deviation. The following concerns were 

found: 

1. Seats did not have lumbar support 

in all of the equipment (100%). 

2. In	 a majority of the equipment 

(86%), the vibration could be felt 

from the equipment through the 

floor. 

3. In	 a majority of the equipment 

(86%), the temperature of the cab 

could not be controlled. 
4. In	 a majority of the equipment (71%), the locations of 

the controls and levers were not 

adjustable. 

5. More than half of the equipment 

(57%) did not have adjustable 

armrests. 

6. In more than half of the equipment 

(57%), vibrations were felt at the 

seats and at the controls. 

7. The seat did not swivel in more 

than half of the equipment (57%). 

Discussion and Conclusion 

Postural requirements of work should 

be considered in the design of work procedures and equipment in construction. 

The relationship between awkward posture and the development of fatigue and 

musculoskeletal disorders has been reported in laboratory and epidemiological 

studies. Despite the fact that operating 

heavy equipment has been found to result 

in a high prevalence of musculoskeletal 

symptoms and injuries,(10) there is a lack 

of quantitative data describing postural 

stresses among operators of construction 

equipment. This could be due to the time 

and complexity in collecting and analyzing postural data. The current study 

introduced a checklist for evaluating cab 

design and presented a case study using 

the checklist. 

The checklist is a general assessment 

tool. The checklist was useful in identifying characteristics that needed improvement. One limitation of a checklist is 

that it is, at best, an analytical tool.(11) 

It can assist in the process of identifying 

potential problems within a system, but 

for quantifying the problems, a comprehensive and systematic methodology is 

required for evaluating the work system. 

The checklist provides a static, instantaneous snapshot of characteristics during 

a specific time. Nevertheless, this and 

other checklists provide the critical point 

of departure in initiating the ergonomic 

analysis.(9,12–14) 

REFERENCES 

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Fatigue — Definition and Measurement. 

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W.M.; et al.: Back Disorders and Nonneutral Trunk Postures of Automobile 

Assembly Workers. Scand J Work Environ Health 17(5):337–346 (1991). 

3. Magora, A.: Investigation of the Relation 

Between Low Back Pain and Occupation: Part I. Indus Med Surg 39(11):465– 

471 (1970). 

4. Chaffin, D.B.; Andersson, G.B.J.: Occupational Biomechanics. John Wiley and 

Sons, New York, NY (1991). 

5. Kelsey, J.L.; Hardy, R.J.: Driving of Motor Vehicles as a Risk Factor for Acute 

Herniated Lumbar Intervertebral Disc. 

Am J Epidemiol 102(1):63–73 (1975). 

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11. Easterby, R.S.: Ergonomics Checklist: 

An Appraisal. Ergonomics 10(5):549– 

556 (1967). 

12. Kittusamy, N.K.; Okogbaa, O.G.; Babu, 

A.J.G.: A Preliminary Audit for Ergonomics Design in Manufacturing Environments. Indus Eng (July, 1992). 

13. Kittusamy,	 N.K.; O’Reilly, J.T.: Ergonomics Program. In: Accident Prevention Manual for Business & Industry: Administration & Programs 

(Occupational Safety and Health Series), 12th ed., chap. 16. P. Hagan; 

J.F. Montgomery; J.T. O’Reilly, eds., 

National Safety Council, Chicago, IL 

(2001). 

14. Keyserling, W.M.; Brouwer, M.; Silverstein, B.A.: A Checklist for Evaluating 

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(1992). 

EDITORIAL NOTE: N. Kumar Kittusamy is a research engineer at NIOSH’s 

Spokane, Washington, Research Lab. He conducts research related to safety and health 

issues in mining and construction industries. 

He holds a B.S. in Industrial Engineering 

and an M.S. in Public Health with concentration in Ergonomics and Industrial Hygiene 

from the University of South Florida, and a 

Doctor of Science (Sc.D.) with a major in Ergonomics and minors in Industrial Hygiene 

and Epidemiology/Biostatistics from the 

College of Engineering at the University of 

Massachusetts Lowell. His current research 

interests include whole-body vibration, musculoskeletal epidemiology, and workstation 

design. 

For more information, Dr. Kittusamy 

can be contacted at NIOSH, Spokane Research Lab, 315 East Montgomery Avenue, Spokane, WA 99207; telephone: (509) 

354-8127; fax: (509) 354-8099; e-mail: 

nfk8@cdc.gov.