• Journal of Korean Society of Transportation
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• v.28 no.2
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• pp.151-159
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• 2010

This paper presents a research result that was performed to develop a more accurate freeway crash prediction model than existing models. While the existing crash models only focus on developing crash relationships associated with highway geometric conditions found on a short section of a crash site, this research applies a different approach considering the upstream highway geometric conditions as well. Theoretically, crashes occur while motorists are in motion, and particularly at freeways vehicle speed at one specific point is very sensitive to upstream geometric conditions. Therefore, this is a reasonable approach. To form the analysis data base, this research gathers the geometric conditions of the West Seaside Freeway 269.3 km and six years crash data ranging 2003-2008 for these freeway sections. As a result, it is found that crashes fit well into Negative Binomial Distribution, and, based on the developed model, total number of crashes is inversely proportional to highway curve length and radius. Contrarily, crash occurrences are proportional to tangent length. This result is different from existing crash study results, and it seems to be resulted from this research assumption that a crash is influenced greatly by upstream geometric conditions. Also, this research provides the expected effects on crash occurrences of the length of downgrade sections, speed camera placements, and the on- and off- ramp presences. It is expected that this research result is useful for doing more reasonable highway designs and safety audit analysis, and applying the same research approach to national roads and other major roads in urban areas is recommended.

• Journal of Korean Society of Transportation
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• v.34 no.4
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• pp.291-303
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• 2016

The number of traffic accidents at intersections has been increased over the past decade, and in 2014, accounted for 44% of the total traffic accidents. In addition, since most of road accident black spots include signalized intersections, the improvement of safety on signalized intersection is top priority for national road safety program in Korea. For the decision of most effective action plan for the safety of signalized intersection, this study conducted meta-analyses to assess the effects of various road safety facilities at signalized intersection on traffic accidents. We selected 19 articles regarding the prediction of traffic accidents at signalized intersection and calculated 34 individual effect sizes on 8 variables included in the articles. The results found that there was a statistically significant negative relationship between the occurrence of traffic accident and the presence of all of road safety facilities except an exclusive left turn bay. It shows that most of the road safety facilities could prevent traffic accidents, and intersection channelization has the most effective on the reduction of traffic accidents followed by left-turn acceleration lane, lightning, crosswalk, exclusive right-turn lane and median barrier.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5585-5593
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• 2014

This study tested the hypothesis that the significance of the heterogeneous dispersion parameter in safety performance function (SPF) used to estimate the expected crashes is affected by the endogenous heterogeneous prior distributions, and analyzed the impacts of the mis-specified dispersion parameter on the evaluation results for traffic safety countermeasures. In particular, this study simulated the Poisson means based on the heterogeneous dispersion parameters and estimated the SPFs using both the negative binomial (NB) model and the heterogeneous negative binomial (HNB) model for analyzing the impacts of the model mis-specification on the mean and dispersion functions in SPF. In addition, this study analyzed the characteristics of errors in the crash reduction factors (CRFs) obtained when the two models are used to estimate the posterior means and variances, which are essentially estimated through the estimated hyper-parameters in the heterogeneous prior distributions. The simulation study results showed that a mis-estimation on the heterogeneous dispersion parameters through the NB model does not affect the coefficient of the mean functions, but the variances of the prior distribution are seriously mis-estimated when the NB model is used to develop SPFs without considering the heterogeneity in dispersion. Consequently, when the NB model is used erroneously to estimate the prior distributions with heterogeneous dispersion parameters, the mis-estimated posterior mean can produce large errors in CRFs up to 120%.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.53-63
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• 2008

Even though accident frequencies in roadway segments have been decreasing since 2000, there has been increasing the number of vehicle crashes at intersections. Due to this increase, safety problems at intersection recently started to be regarded as significant issues. The purpose of this study is to analyze the effects of road conditions, traffic operational conditions, and other influencing condition on intersection safety. Then a traffic accident frequency prediction model to evaluate the safety at intersections was developed based on the correlations between influencing factors and vehicle crashes. In this research, critically significant factors affecting vehicle crashes at rural four-legs signalized intersections were investigated. It was found that Poisson regression was the best fit method to developing a accident frequency modeling using the collected data in this study. Through this study, it was concluded that exclusive left turn lane, crosswalk, posted speed, lighting, angle, and ADT are significant influencing factors on the intersection safety.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.3
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• pp.11-18
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• 2013

Since 1996, Korean National Police Agency has been promoting a project for installation of Automated Speed Enforcement (ASE) system aiming at reduction of accidents. The number has increased to 5,348 stations throughout country as of December 2012. Recently, the Section Speed Enforcement Systems have been installed at many sites to produce a general effect well beyond the localised effect at overt fixed camera sites. In this study aims, we have analyzed the effects of the Section Speed Enforcement System at the Misiryeong tunnel section. We have found that there were a statistically significant 21.4%~31.% reduction of the average speed and 45.9% reduction in a number of traffic accidents per month. Accordingly, the study indicates that the Section Speed Enforcement Systems at Misiryeong tunnel section has effective to produce road safety.

• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.46-52
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• 2017

During the transportation of chemicals, quantitative risk assessment for chemical leakage accidents caused by traffic accidents was carried out and the appropriateness of chemical transportation route was evaluated. The quantitative risk assessment method applied to the chemical leakage accidents that may occur in the chemical handling equipments installed in the workplace was presented and applied to the chemical transportation. By analyzing the number of traffic accidents in transportation vehicles, the probability of chemical leakage accidents during chemical transportation was predicted and applied to the quantitative risk assessment of chlorine gas leakage accidents that may occur when transporting liquified chlorine bombe using vehicles. As a result, the most appropriate route of transporting the liquefied chlorine bombe was suggested on the basis of risk.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.89-96
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• 2016

According to the promoting policy for bicycle riding, the bicycle road infrastructure in Korea has been widely established. As the number of bicycle rider increases, bicycle traffic accidents also increase year after year. In this paper, we analyze bicycle traffic accident data from 2007 to 2014 which is provided by Road Traffic Authority and present statistical results of bicycle traffic accidents. And also regression analysis is applied to predict the number of daily traffic accidents in Seoul using ASOS(Automated Synoptic Observing System) climate data observed in the Seoul sector which are provided by Korea Meteorological Administration. In addition, decision tree analysis techniques are used to forecast the level of traffic accidents severity. In the analytic results of this research, we expect that it will be helpful to establish the collective policy of bicycle accident data and protective strategy in order to reduce the number of bicycle accidents.

• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.109-117
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• 2008

The first phase of School Zone Improvement Project introduced to enhance the safety of school-routes were completed by 2007 and the second phase of the project will be continued from 2008 to 2012. Since a huge budget is required for the project, there is a need to evaluate how many child-related crashes were reduced through the project, prior to the implementation of the second phase. Therefore, this study aims to analyze the influence of the School Zone Improvement Project on reduction in child-related crashes with data collected from the database of the National Police Agency. This study employed a Before-and-After study with comparison group to assess how many crashes were reduced. The results showed that the number of child-related crashes were decreased by 10, which is about 39% reduction in crash frequencies. With respect to the land use characteristics of school zones, the number of reduced crashes in residential zone, commercial zone, and mixed zone were 2.41, 3.8, and 0.5, respectively. The results may provide a significant implication for the second phase of the project that there is a need to establish different plans for improvement project with respect to land use characteristics.

• The Journal of the Korea Contents Association
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• v.20 no.9
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• pp.430-438
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• 2020

Many local governments are reducing speed limits according to the "Safe Speed 5030" policy implemented by the government to reduce traffic accident deaths. In the urban road sections in many metropolitan cities where speed limit reduction is applied as a pilot project, the decrease effect of the traffic accident number and death count is shown; however, no study of the effect analysis on the road sections of medium and small cities (basic local government unit) is found. Therefore, this study investigated the travel speed, number of traffic accidents, and death count before and after the implementation of speed limit reduction, targeting some urban road sections in Pyeongtaek city and some provincial road sections in Icheon city among basic local governments, namely among medium and small cities in Seoul Metropolitan Area.

• Journal of Korean Society of Transportation
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• v.18 no.1
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• pp.35-43
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• 2000

The Purpose of this Paper was to study the relationship between the change of operating speeds and the accidents on horizontal curves. For this purpose, we divided a horizontal curve section into two parts, a tangent section and a curve section, to estimate the operating speed for each vehicle. For studying relationship between the change of speed and geometric effect, the free-flow speed was used. The location and speed for the lowest speed were studied. Also, we analyzed the relationship between the change of operating speeds and the accidents. The followings are resulted in this study. First, drivers tend to reduce speeds significantly before they reach a curve. And the lowest speed was recorded at the downstream of the Point of curve (PC) due to the limited sight-distance of drivers on curve. Second, the larger the change of operating speeds become, the greater frequency of accident was recorded. These results can be used for developing the safety index on highways to check the design consistency.