• Journal of the Korean Society of Safety
• /
• v.27 no.6
• /
• pp.178-184
• /
• 2012

This study deals with the traffic accidents by weather condition. The objectives are to comparatively analyze the characteristics, and to develop the models of traffic accidents by weather condition. In pursuing the above, this paper gives particular attentions to testing the differences between two groups, and developing the models(Poisson and negative binomial regression) using the data of domestic circular intersections. The main results are as follows. First, three Poisson models and one negative binomial models which were all statistically significant were developed using the number of accident and EPDO by the clear weather and other as the dependant variables. Second, the differences between two models were comparatively analyzed using the chosen variables. This paper might be expected to give some implications to traffic safety policy-making to reduce and prevent the traffic accidents in circular intersections.

• Journal of Korean Society of Transportation
• /
• v.34 no.6
• /
• pp.489-498
• /
• 2016

The objective of this study is to develop road traffic accident model involving child pedestrian especially at school zones and its surrounding area. The analysis is based upon traffic accident data collected near sixty elementary schools in City of Cheongju during 2012 and 2014. This study results in two statistical models ; one is to predict the number of road traffic accidents involving children, and the other is to predict EPDO(Equivalent Prperty Damage Only). These models are represented as Poisson models. which are statistically significant with the likelihood ratios of 0.533 and 0.273. The common explanatory variables of these models are the ratio of road section with more than 4 lanes, the number of entrance and exit, the number of signalized crosswalk in school zone, the number of school zone signage including road surface marking, and the number of speed limit signs. The specific variables are the length of road stretch in school zone, the number of reflector mirrors, and the number of signalized crosswalk outside school zone. It is concluded that these types of road safety facilities can reduce the number of traffic accidents involving children at school zones and its surrounding area.

• Journal of Korean Society of Transportation
• /
• v.21 no.2
• /
• pp.45-60
• /
• 2003

A median is a safety feature most commonly used to separate opposing traffic on a divided highway. In designing highways, the selection and installation of a median can be a critical part from a safety viewpoint because road crossing accidents are definitely more serious than other accidents. In regard to the important function of the median. the proper countermeasure ought to have been provided and thorough study should have been carried out. In this paper, traffic accident data are analyzed to examine the accident reduction effect of the median, which are gathered from all over 4-lane national roads in Korea. The traffic accident data were categorized into two groups by the existence of a median. For more effective analysis, the data have been classified by accident type, severity. and occurrence time. To compare the effectiveness of median installation, not only the accident frequency but also the accident severity, EPDO. and the occupancy rate of specific accidents have been used as a mode of effectiveness. The analysis of the effectiveness of medians shows that both the accident frequency and the accident severity could decrease by providing a median. Also the section where a median was supplied showed the improvement of overall safety through fewer serious and fatal crashes as well as fewer head-on crashes. Therefore, conclusions can be drawn from results of this study that the median installation is an important means to increase the safety of over 4-lane national roads. This study is expected to provide the reasonability of the median installation by identifying the reduction of traffic accident after the median installation and to play a major role in selecting sections where the median is to be offered.

• Journal of Korean Society of Transportation
• /
• v.29 no.4
• /
• pp.95-101
• /
• 2011

This study proposes the accident estimation model developed based on the time-series cross-sectional data at 50 intersections in Cheongju. The data were collected repeatedly and accumulated from 2004 to 2007. This study focused on deriving the optimal among the various models including TSCSREG(Time Series Cross Section Regression). Four different models utilizing various elements affecting accidents were developed. Through a statistical test, it was found that the t values of independent variables of the fixed effect models were less than those of the random effect models. Two variables were then found to be positive to the accidents: the number of crosswalks at an intersection and the number of intersections.

• Journal of the Korean Society of Safety
• /
• v.27 no.3
• /
• pp.141-146
• /
• 2012

This study deals with the accident model using panel data which are composed of time series data of 2005 through 2007 and cross sectional data of link sections in Cheongju. Panel data are repeatedly collected over time from the same sample. The purpose of the study is to develop the traffic accident model using the above panel data. In pursuing the above, this study gives particular attentions to deriving the optimal models among various models including TSCSREG (Time Series Cross Section Regression). The main results are as follows. First, 8 panel data models which explained the various effects of accidents were developed. Second, $R^2$ values of fixed effect models were analyzed to be higher than those of random effect models. Finally, such the variables as the sum of the number of crosswalk on intersections and sum of the number of intersections were analyzed to be positive to the accidents.

• International Journal of Highway Engineering
• /
• v.13 no.3
• /
• pp.103-110
• /
• 2011

This study deals with the traffic accidents by type. The objectives are to analyze the characteristics of 2 accident types, and to develop the models by type. In pursuing the above, this paper gives particular attentions to testing the differences between by type two groups, and developing the models (Poisson and negative binomial regressions) using the data of domestic circular intersections. The main results are as follows. First, the number of accidents in vehicle vehicle was analyzed to account for about 73.41% of total and to be higher than vehicle people. Second, two Poisson models and two negative binomial models which were all statistically significant were developed using vehicle people accidents and vehicle vehicle accidents as dependant variables. Finally, the traffic volume as common variable was selected in the models, and right-turn slip lane, speed hump, the number of driveways, the number of pedestrian crossings as specific variables of the models were selected.

• Journal of Korean Society of Transportation
• /
• v.27 no.5
• /
• pp.135-144
• /
• 2009

This study estimates the expected number of accidents in Kyungbuk Province to capitalize on experience gained from four years of accident history using the Empirical Bayes (EB) Method. The number of accidents of each site in Kyungbuk Province is recalculated using the Equivalent Property Damage Only (EPDO) method to reflect the severities of the accidents. A cluster analysis is performed to determine similar sites and a unique Safety Performance Function (SPF) is established for each site. The overdispersion parameter is built to correct the difference between the actual number of accidents and the underlying probability distribution. To adjust for varying traffic characteristics of each site, a relative weight is applied and eventually estimates the expected number of accidents. The results show that the highest accident sites are Kimcheon, Youngcheon, and Chilgok, but on the other hand the lowest is Gunwi.

• Journal of Korean Society of Transportation
• /
• v.20 no.2
• /
• pp.105-115
• /
• 2002

For many rears, traffic accident statistics are the most direct measure of safety for a signalized intersection. However it takes more than 2 or 3 yearn to collect certain accident data for adequate sample sizes. And the accident data itself is unreliable because of the difference between accident data recorded and accident that is actually occurred. Therefore, it is rather difficult to evaluate safety for a intersection by using accident data. For these reasons, traffic conflict technique(TCT) was developed as a buick and accurate counter-measure of safety for a intersection. However, the collected conflict data is not always reliable because there is absence of clear criteria for conflict. This study developed objective and accurate conflict criteria, which is shown below based on traffic engineering theory. Frist, the rear-end conflict is regarded, when the following vehicle takes evasive maneuver against the first vehicle within a certain distance, according to car-following theory. Second, lane-change conflict is regarded when the following vehicle takes evasive maneuver against first vehicle which is changing its lane within the minimum stopping distance of the following vehicle. Third, cross and opposing-left turn conflicts are regarded when the vehicle which receives green sign takes evasive maneuver against the vehicle which lost its right-of-way crossing a intersection. As a result of correlation analysis between conflict and accident, it is verified that the suggested conflict criteria in this study ave applicable. And it is proven that estimating safety evaluation for a intersection with conflict data is possible, according to the regression analysis preformed between accident and conflict, EPDO accident and conflict. Adopting the conflict criteria suggested in this study would be both quick and accurate method for diagnosing safety and operational deficiencies and for evaluation improvements at intersections. Further research is required to refine the suggested conflict criteria to extend its application. In addition, it is necessary to develope other types of conflict criteria, not included in this study, in later study.