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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society of Transportation
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Korean Society of Transportation
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Volume & Issues
Volume 34, Issue 3 - Jun 2016
Volume 34, Issue 2 - Apr 2016
Volume 34, Issue 1 - Feb 2016
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Mobile Source Emissions Estimates for Intra-zonal Travel Using Space Syntax Analysis
LEE, Kyu Jin ; CHOI, Keechoo ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 107~122
DOI : 10.7470/jkst.2016.34.2.107
This study aims to develop a framework to estimate mobile source emissions with the macroscopic travel demand model including enhanced estimates of intra-zonal travel emissions using Space Syntax analysis. It is acknowledged that "the land-use and transportation interaction model explains the influence of urban structure on accessibility and mobility pattern". Based upon this theory, the estimation model of intra-zonal travel emissions is presented with the models of total travel distance, total travel demand, and average travel speed of intra-zonal trips. Thess statistical models include several spatial indices derived from the Space Syntax analysis. It explains that urban spatial structure is a critical factor for intra-zonal travel emissions, which is lower in compact zone with smaller portion of land area, lower sprawl indicator, and more grid-type of road network. Also the suggested framework is applied in the evaluation of the effectiveness of bicycle lane project in Suwon, Korea. The estimated emissions including intra-zonal travel is as double as the results only with inter-zonal demands, which shows better performance of the suggested framework for more realistic outcomes. This framework is applicable to the estimation of mobile source emissions in nation-wide and the assessment of transportation-environment policies in regional level.
Analysis of Contributory Factors in Causing Crashes at Rural Unsignalized intersections Based on Statistical Modeling
PARK, Jeong Soon ; OH, Ju Taek ; OH, Sang Jin ; KIM, Young Jun ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 123~134
DOI : 10.7470/jkst.2016.34.2.123
Traffic accident at intersections takes 44.3% of total number of accidents on entire road network of Korea in 2014. Although several studies addressed contributory factors of accidents at signalized intersection, very few is known about the factors at rural unsignalized intersections. The objective of this study is therefore to investigate specific characteristics of crashes at rural unsignalized intersection and to identify contributory factors in causing crashes by statistical approach using the Ordered Logistic Regression Model. The results show that main type of car crashes at unsignalized intersection during the daytime is T-bone crashes and the number of crashes at 4-legged intersections are 1.53 times more than that at 3-legged intersections. Most collisions are caused by negligence of drivers and violation of Right of Way. Based upon the analysis, accident severity is modeled as classified by two types such as 3-legged intersection and 4-legged intersection. It shows that contributory factors in causing crashes at rural unsignalized intersections are poor sight distance problem, average daily traffic, time of day(night, or day), angle of intersection, ratio of heavy vehicles, number of traffic violations at intersection, and number of lanes on minor street.
Analysis of Green Vehicle Purchasing Behavior Using Logit Model
HAHN, Jin-Seok ; LEE, Jang-Ho ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 135~145
DOI : 10.7470/jkst.2016.34.2.135
This study assumes a vehicle choice model based on the multinomial model and analyzes the vehicle choice behaviors of consumer. An SP survey targeting drivers was implemented and data was collected for model estimates, with the possible choice options of the survey takers limited to gasoline, HEV, PHEV, and EV vehicles. The explanatory variable mostly displayed a significance level of under 5%, and excluding variables for price and fuel the remaining variables were all consistent with the logical direction with the plus (+) sign and the results were determined to be rational. Consumers selecting mid-size & full-size vehicles are able to afford more than consumers that selected other vehicle types, so there was relatively little consideration given to low fuel costs when compared to vehicle price. For this reason, it was determined that for the full-size vehicle model the fuel variable could be disregarded. Socio-economic variables that were statistically significant were the age and infor variables for the sub-compact & compact, the age, infor and inc3 variables for the mid-sized & full-size vehicles.
A Statistical Fitness Test of Newell's 3-detector Simplification Method for Unexpected Incident Detection in the Expressway Traffic Flow
OH, Chang-Seok ; RHO, Jeong Hyun ; PARK, Young Wook ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 146~157
DOI : 10.7470/jkst.2016.34.2.146
The objective of this study is to actualize a statistical model of the 3-detector simplification model, which was proposed to detect outbreak situations by Daganzo in 1997 and to verify the statistical appropriacy thereof. This study presents the calculation process of the 3-detector simplification model and realizes the process using a statistics program. Firstly, the model was applied using data on detector of the main highways on which there is no entrances or exits. Moreover, in order to statistically verify the 3-detector simplification model, accumulative traffics for 30 seconds period, which reflects the dynamic changes of traffics due to shock wave, were estimated for outbreak traffics and steady flow, and the error of acquired data was statistically compared with that of the actual accumulative traffics. As a result, the error ratio between steady and incident cumulative flows has reached its maximum after 2-3 hours from an accident. Moreover, the incident traffic flows by accidents and the stade flows are heterogeneous in terms of their dispersion and means.
Short-term Traffic States Prediction Using k-Nearest Neighbor Algorithm: Focused on Urban Expressway in Seoul
KIM, Hyungjoo ; PARK, Shin Hyoung ; JANG, Kitae ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 158~167
DOI : 10.7470/jkst.2016.34.2.158
This study evaluates potential sources of errors in k-NN(k-nearest neighbor) algorithm such as procedures, variables, and input data. Previous research has been thoroughly reviewed for understanding fundamentals of k-NN algorithm that has been widely used for short-term traffic states prediction. The framework of this algorithm commonly includes historical data smoothing, pattern database, similarity measure, k-value, and prediction horizon. The outcomes of this study suggests that: i) historical data smoothing is recommended to reduce random noise of measured traffic data; ii) the historical database should contain traffic state information on both normal and event conditions; and iii) trial and error method can improve the prediction accuracy by better searching for the optimum input time series and k-value. The study results also demonstrates that predicted error increases with the duration of prediction horizon and rapidly changing traffic states.
An Improved LOS Analysis Method for Pedestrian Walkways Using Pedestrian Space
JUN, Sung Uk ; SON, Yonug Tae ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 168~179
DOI : 10.7470/jkst.2016.34.2.168
This study describes an improved model for estimating pedestrian LOS (Level of Service) by utilizing the space occupied by pedestrians. The method introduced the concept of conflict along the bi-directional pedestrian flow which enables calculating conflict area and average travel time in walking. Especially, the method incorporates the idea of generalized density concept which can consider effective walking area and pedestrian flow rates that might vary during the analysis period. After establishing methodology, adjustments of pedestrian LOS criteria in term of walking space occupied by pedestrians were performed. As a result, walking-occupied space at capacity level is 0.68 and corresponding pedestrian flow rate was calculated as 80 persons/min/m, while different pedestrian-occupied spaces were ordered to classify LOS at the points where the gradient changes. Furthermore, the statistical verification of service levels has shown that there is significant difference among all LOS categories at 5% significance level.
A Study for Developing an Operating Mode-Based Emission Model for Korea
HU, Hyejung ; FREY, Christopher ; YOON, Chunjoo ; YANG, Choongheon ; KIM, Jinkook ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 180~190
DOI : 10.7470/jkst.2016.34.2.180
Atmospheric pollutants such as Nitrogen Oxides(NOx), Carbon Monoxide(CO), Carbon Dioxide(
), Particulate Matter(PM) and Hydrocarbons(HC) come from vehicle exhaust gases. Emission curves based on average travel speeds have been employed for estimating on-road emissions as well as evaluating environmental impacts of transportation plans and policies in Korea. Recently, there is a growing interest in estimation methods of vehicle emissions considering relationship between vehicle dynamic driving characteristics and emissions, and incorporating such emission estimators into traffic simulation models. MOVES Lite, a simplified version of MOVES, is one of the estimation methods. In this study, the authors performed a study to develop an adaptable version of MOVES Lite for Korea, called MOVES Lite-K. Vehicle types, driving characteristics, emission rates, and emission standards of Korea were reflected in MOVES Lite-K. The characteristics of emission calculation of MOVES Lite-K and NIER emission curves were compared and the adaptability of MOVES Lite-K were examined.
Development of Criteria for Determining Level of Service for Pedestrian Walkway Considering a Pedestrian Platoon: Focusing on the Hongik University Area
CHOI, Sung Taek ; CHOO, Sang Ho ; JEON, Na Yeong ;
Journal of Korean Society of Transportation, volume 34, issue 2, 2016, Pages 191~206
DOI : 10.7470/jkst.2016.34.2.191
Pedestrian performance measurement has generally used the average values of pedestrian volumes and speeds from a sample, although each individual's pedestrian behavior of the sample is mainly affected by his/her socio-economic and physical characteristics. In particular, if such individual characteristics of the sample have wide variations, the average values are hard to be representative. In this respect, this study found that a platoon of pedestrians had a major effect on their pedestrian flows on sidewalks. The more platoons was mixed on pedestrian roads, the lower pedestrian flow rate was. The indexes such as a pedestrian flow rate and an occupancy space are typically calculated by pedestrian volumes in a given period of time regardless of the existence of a platoon. However, it is plausible that a pedestrian speed and a level of pedestrian congestion can be different under the equal amount of pedestrian volumes. Therefore, this study suggested criteria for determining level of service for pedestrian considering platoon effects and confirmed that two places had different pedestrian LOSs because of the platoon effects, even if they showed the same pedestrian flow rate.