• International Journal of Highway Engineering
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• v.19 no.2
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• pp.167-174
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• 2017

PURPOSES: This study aims to analyze the impact of the implementation of a school zone traffic safety improvement project on the number of accidents involving children in these zones. METHODS : To analyze the correlation between school zone traffic safety features of roads in the zone and the number of accidents involving children, we developed an occurrence probability model of traffic accidents involving children by using a binary logistic regression model with SPSS 23.0 software. Two separate models were developed for two zones: interior block and arterial road. RESULTS :The model depicted that in the case of the interior block, shorter sidewalk width, speed bump, and an elevated crosswalk were key factors affecting the occurrence of accidents involving children. In the case of arterial roads exceeding a width of 12 m, the speed limit, roadside barriers, and red paving of road surfaces were found to be the key factors. CONCLUSIONS:The results of this study can serve as the elementary research data to help improve the effectiveness of school zone traffic safety improvement projects and school zone road repair projects in future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4A
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• pp.197-206
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• 2012

It is found the first case of broad interpretation of the crash analysis in MASH (Manual for Assessing Safety Hardware, AASHTO, 2009) which is the guideline of roadside safety features in United States. They introduced the procedure of calculating 1,500 kg sedan safety index from the 2,270 kg pick-up truck crash test for crash cushion. First, following MASH's method, calculate 0.9 ton vehicle crash data and safety index using 1.3 ton vehicle crash test data and compare with actual 0.9 ton vehicle crash test data. results show that actual test data and the data calculated by MASH's method have great difference. Second, analyse the cause and develop new method. Proposed method can estimate not only the lighter vehicle (0.9 ton) crash data from the heavier vehicle (1.3 ton) crash test but also heavier vehicle (1.3 ton) data from lighter vehicle (0.9 ton) test. This method is superior to MASH's method and has stronger theoretical foundation. This paper proves the efficiency and the accuracy of new broad interpretation method using crash test data and investigates the principle.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.132-146
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• 2017

Appropriate speed limits at a reasonable level in urban roads are highly important factors for efficient and safe movement. Thus, it is greatly necessary to develop the objective models or methodology based on engineering study considering factors such as traffic accident rates, roadside development levels, and roadway geometry characteristics etc. The purpose of this study is to develop the estimate model of appropriate speed limits at each road sections in urban roads using traffic information big data and field specific data and to review the effects of accident decrease. In this study, the estimate method of appropriate speed limits in directional two or more lanes of urban roads is reflecting features of actual variables in a form of adjustment factor on the basis of the maximum statutory speed limits. As a result of investigating and testing influential variables, the main variables to affect the operating speed are the function of road, the existence of median, the width of lane, the number of traffic entrance/exit path and the number of traffic signal or nonsignal at intersection and crosswalk. As a result of testing this model, when the differences are bigger between the real operating speed and the recommended speed limits using model developed in this study, the accident rate generally turns out to be higher. In case of using the model proposed in this study, it means accident rate can be lower. When the result of this study is applied, the speed limits of directional two or more lane roads in Seoul appears about 11km/h lower than the current speed limits. The decrease of average operating speed caused by the decrease of speed limits is 2.8km/h, and the decrease effect of whole accidents according to the decrease of speed is 18% at research road. In case that accident severity is considered, the accident decrease effects are expected to 17~24% in fatalities, 11~17% in seriously injured road user, 6~9% in slightly injured road user, 5~6% in property damage only accidents.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.23-30
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• 2009

Crash cushions are protective devices that prevent errant vehicles from impacting on fixed objects. This function is accomplished by gradually decelerating a vehicle to a safe stop in a relatively short distance. Commonly used crash cushions generally employ one of two concepts to accomplish this function. The first concept involves the absorption of the kinetic energy of a moving vehicle by crushable or plastically deformable materials and the other one involves the transfer of the momentum of a moving vehicle to an expendable mass of material located in the vehicle's path. Crash cushions using the first concept are generally referred to as compression crash cushions and crash cushions using the other concept are generally referred to as inertial crash cushion. The objective of this research is the development of a compression-type crash cushion by employing the two concepts simultaneously. To minimize the number of full-scale crash tests for the development of the crash cushion, preliminary design guide considering inertial and frictional energy absorption was constructed and computer simulation was performed. LS-DYNA program, which is most widely used to analyze roadside safety features, was used for the computer simulation. The developed crash cushion satisfied the safety evaluation criteria for various impact conditions of CC2 performance level in the Korean design guide.