Ergonomic evaluation of interior design of Shoka vehicle and proposing recommendations for improvement Adel Mazloumi * , PhD Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammadreze Fallah, MSc Department of Ergonomics, University of Social Welfare andRehabilitation Sciences, Tehran, Iran Hedayat Tavakoli, MSc Department of Occupational Health, Polytechnic University of Chamran, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Objectives: One of the applications of ergonomics disciplinary is designing driver workstation compatible to users characteristics. The aim of this study was evaluation of interior design of Shoka vehicle with respect to the accommodation for Iranian population and proposing suggestions for customizing design of the vehicle. Method: This study was a descriptive-analytical study conducted among thirty men from Iranian drivers population in 5, 50, 95 percentiles of the stature variable. Objective variables related to the occupant packaging and vehicle visual aspects including anthropometric variables, frontal, lateral, and side view and so on were investigated first. Then, subjective variables related to the driver mental workload and body comfort discomfort were studied using BMDMW and comfort questionnaires during 2-hour driving trial sessions. Results: Occupant packaging variables and hand-arm angle showed the least accommodation percent(%53).Seating angles showed low accommodation as well (%73). Among three percentile groups there were no significant differences between the mean values of mental Workload during two hours driving task. The mean value related to the comfort discomfort was 3.9 during driving sessions. Conclusion: Considering the findings in this study, it can be concluded that seating angles need correction and optimization. Taking mental workload results into account, it can be concluded that the interior design of the studied car had no influence on driversmental workload. From the aspect of comfort/discomfort, Shoka vehicle showed neutral state among drivers.Optimizing seating angles, decreasing vibration, correcting stiffness of seating pan are suggested for customization of the ergonomics aspect of this vehicle. Keywords: Ergonomic evaluation, Vehicle, Shoka, Anthropometric, Compatibility Introduction Safety and comfort are of the most important criteria for both car manufacturing companies and for drivers as well as occupants from many points of views. Therefore considering the principles of ergonomics in automotive design will make remarkable benefits to many extents .Different researches have shown that fatigue played an important role in incidence of thirty percent of traffic accidents. One of the major causes of fatigue while driving is the car interior design. Features such as seats, steering wheel and pedals have shown a large impact on driver fatigue. The interior design may also cause human error .Inappropriate design of the vehicle may lead to some health problems among driver population as well. The risk of lumbar discs deformation, pain in neck, back and shoulder tension,reduced blood circulation in the legs and buttocks are the instances of those problems .Moreover, interior design has impact on driver mental workload.Mental workload refers to engaging the mind while performing a task like driving task. Problems such as distraction,performance reduction and human error are somehow related to the drivers mental workload.Several ergonomics indicators are used by car manufacturing companies for car design evaluation. These indicators are either qualitative (subjective) or quantitative indicators.Qualitative indicators are achieved with the use of questionnaires and special checklists among users population.Quantitative indicators such as anthropometric measures, access limits,forces and so on are also used to evaluate interior design and its compatibility with the user population in different percentiles. Several questionnaires, such as BMDMW and body comfort-discomfort questionnaire,have been published to evaluate the vehicle design. BMDMW questionnaire is a subjective measure based on driving behavioral patterns which evaluate driversmental workload and state.Body comfort discomfort questionnaire also evaluate whole body and comfort-discomfort related to body limbs.Quantitative indicators to assess ergonomics-related aspects of interior design are generally related to the design dimensions.Dimensions can indicate human accommodation;and many research studies are based on evaluating those dimensions in 5,50,95 percentiles.The greatest differences in anthropometric values that are more relevant to the driver accommodation are three variables:stature, sitting height and weight. But, some research studies have shown that stature is most important anthropometric variable involved in the automotive design .Occupant packaging