Development and Evaluation of Bus Seat Dimension to Improve the Fit and Comfort of Malaysian Bus Drivers
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2.2. Anthropometry data of bus drivers
A cross-sectional study was conducted to measure the anthropometric dimensions of Malaysian Commercial Vehicle Bus Drivers Table 1. A total of 176
bus drivers from seven bus depots in the Klang Valley serving the capital city participated in the study. Twelve anthropometric parameters were measured using
Martin’s type anthropometer; however, only ten were relevant to the seat design:
• buttock-popliteal depth; 1
• sitting eye height; 2
• weight; 3
• shoulder height; 4
• elbow-rest height; 5
• knee height; 6
• popliteal height; 7
• hip breadth; 8
• buttock-knee depth, 9
• and lumbar support height.10
2.3. Body part symptom survey
Twenty five drivers who used these seats were interviewed to identify any musculoskeletal pain that might be related to the design of the seat used. A body
part symptom figure was used based on the sitting posture; drivers were asked to indicate the body parts experiencing problems, i.e., neck and head, shoulder, upper
back, arm and hand, lower back, thigh, knee and ankle and leg. The frequency of the response for each part was calculated.
2.4. Modeling and evaluating the seat design
Seat designs were then modeled using CATIA software version V5R14. The CATIA software was used to design and simulate the current and recommended
seat using the anthropometric dimensions of the bus drivers. The Rapid Upper Limb Assessment RULA tool available in the software was used to give a quick
assessment of the potential problems that bus drivers may encounter with each seat design and to justify the need for a better seat design.
2.4.1. RULA analysis
RULA [15] is an ergonomic technique for evaluating individuals’ exposures to postures, forces and muscle activities that have been shown to contribute to
Repetitive Strain Injuries RSIs. Use of this ergonomic evaluation approach results
M.Y. Rosnaha et al. AJE Vol.9 2009 1-17
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in a risk score between one and seven, where higher scores signify greater levels of apparent risk. RULA analysis examines the following risk factors: number of
movements, static muscle work, force, working posture, and time worked without a break. RULA evaluates stress on each body part; the level of severity suggests which
features of the chair should be modified to make it more comfortable.
2.4.2. Current seat measurement
Several measurements were taken on the current seat Figure 3.
3. Results
3.1. Sampling and Observation
The seats in the three buses sampled, none had armrests, headrests or seatbelts. Armrests support the arms and prevent or reduce arm, shoulder, and neck fatigue.
The headrest supports the weight of the head to reduce amount of stress on the body. Therefore adding armrests and a headrest should reduce fatigue among bus
drivers. However, the lack of a seat belt simply showed a disregard for safety.
3.2. Body part Symptom survey
The respondents for this study were mostly 12 31-40 years old and had worked as bus drivers for an average of 5-7 years. Of the 25 respondents, 18
indicated that they experience some musculoskeletal problems and 16 of these indicated that these problems first occurred after they had become drivers. In 23 of
the workers, the most frequent problems were in the lower back, followed by pain in the neck or head 21, in the ankle or leg 20, in the thigh 17 and in the arm or
hand 15. This result is consistent with that of the larger survey. Based on interviews and chair design observation, possible causes of the prevalent problems
were identified Table 1.
3.4. Current Seat measurement
The measurements the current seat Table 3 will be compared with the relevant anthropometric data to recommend a new seat design.
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