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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 20, Issue 7 - Dec 2002
Volume 20, Issue 6 - Dec 2002
Volume 20, Issue 5 - Oct 2002
Volume 20, Issue 4 - Aug 2002
Volume 20, Issue 3 - Jun 2002
Volume 20, Issue 2 - Apr 2002
Volume 20, Issue 1 - Feb 2002
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Analysis on driver's visual behaviour at the curve sections of a national road for enhancing traffic safety
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 7~16
It is very important to research drivers' visual behavior. Angle of vision is very important and accounts for more than 90% as the source of driving information. In curve sections, drivers can know the front circumstances and drive more safely and comfortably through facilities guiding their eye movements. Therefore, the standards of installation and effectiveness of these facilities to guide drivers' gaze need to be reconsidered considering characteristics of drivers' eyes The national road no. 34 (Jincheon IC, Buckamri-Yiriangmun section), which is a high-accident-frequency location, is chosen for experimental place. The aim of this study is to understand the process of drivers' visual movement which is drivers' visual behavior and to check the facilities to guide their eyes. Another goal of this study is to improve facilities to guide drivers' eyes on a result basis of considering drivers' visual behavior especially for traffic safety in a high-accident-frequency curve sections.
Development of Freeway Incident Duration Prediction Models
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 17~30
Incident duration prediction is one of the most important steps of the overall incident management process. An accurate and reliable estimate of the incident duration can be the main difference between an effective incident management operation and an unacceptable one since, without the knowledge of such time durations, traffic impact can not be estimated or calculated. This research presents several multiple linear regression models for incident duration prediction using data consisting of 384 incident cases. The main source of various incident cases was the Traffic Incident Reports filled out by the Motorist Assistant Units of the Korea Highway Corporation. The models were proposed separately according to the time of day(daytime vs. nighttime) and the fatality/injury incurred (fatality/injury vs. property damage only). Two models using an integrated dataset, one with an intercept and the other without it, were also calibrated and proposed for the generality of model application. Some findings are as follows ; ?Variables such as vehicle turnover, load spills, the number of heavy vehicles involved and the number of blocked lanes were found to significantly affect incident duration times. ?Models, however, tend to overestimate the duration times when a dummy variable, load spill, is used. It was simply because several of load spill incidents had excessively long clearance times. The precision was improved when load spills were further categorized into "small spills" and "large spills" based on the size of vehicles involved. ?Variables such as the number of vehicles involved and the number of blocked lanes found not significant when a regression model was calibrated with an intercept. whereas excluding the intercept from the model structure signifies those variables in a statistical sense.
A study on Left turn Capacity by Bay Length
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 31~39
The primary objective of this study is to develop a reliable method for estimating the left turn capacity at the signalized intersection. This study is performed during periods of congestion. Multi left turn lane(bay lane and exclusive lane) approaches are examined. When more than one left turn lane exists, traffic volumes are not distributed equally over each lane. The fundamental approach taken in this study is measuring headways on left turn lanes with altering the bay length from 20m to 120m. Left turn lane is divided into 3 sub-sections in this study. These are SLP section(start-up lost time Period), SFP section(saturation flow period), LSP section(lane selection period). Saturation flow rates are evaluated for each sub section periods. As a results of analysis, it has been confirmed that the left turn capacity can be estimated by left turn bay length and effective green time for left turn. The left turn bay length adjustment factor is suggested in this study.
Value of Freight Travel-Time Savings for Road Investment Evaluation
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 41~52
Most investment evaluations and economic assessments of road transport proposals in Korea omit a valuation of the time spent in transit for loads of freight. These days there were few attempts to estimate value of freight travel-time savings in Korea, but most of them included rail or marine with statewide area so that couldn't obtain unique travel-time savings for road freight transport. This study applied revealed Preference method and associated binominal logit models to estimate the value of travel-time savings in transit from an statewide survey of road freight transport in 1997. Data sets were segmented according to transport areas and business types. The results of this study showed that the value of freight travel-time savings varied wide ranges from 53,449 won per hour in urban transport to 29,397 won per hour in regional transport, that the use of statewide value of freight travel-time savings can drives wrong results into economic assessment, and that the use of adequate value of freight travel-time savings according to assessment area is very important.
A study on Link Travel Time Estimating Methodology for Traffic Information Service (Determination of an Adequate Sample Size)
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 55~67
Link travel time information can be an important criterion for driver's route choice behaviors. In general, the link travel time informations are provided based on the directly collected travel time data using GPS-equipped Probe vehicles. In this paper, a framework for determining adequate sample sizes was proposed to provide reliable link travel times in the real world. The link travel times of signalized arterials are composed of cruise times and intersection delays, while those of urban freeways were cruise times. The adequate sample sizes of signalized arterials and urban freeways were determined based on the central limit theorem. The reliability of the link travel time estimated were tested by comparing the observed link travel time. The result shows that link travel times estimated in this study were reliable to the 95% confidence interval and within the error limit of 5㎞/h.
A Study on Describing Uninterrupted Traffic Flows using Macroscopic Models
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 69~82
The objective of this study is to evaluate the performance of macroscopic traffic flow models with the analytical and field data. Five candidate models were selected as follows ; Lax Method Model, Upwind Scheme Model, Hilliges'Model, Papageorgiou's Model, and Cell-Transmission Model. In the analytical test scenario, the traffic condition was assumed that could cause the building and dissipation of queue, and each model was compared with analytical solutions and the numerical results. An analytical test indicated that both simple continuum and high order continuum models are able to reproduce queue building and dissipating behavior in a reasonable way A field test has shown that Upwind and Papageorgiou's model show similar performances. Considering the simplicity in model formulation and numerical computation, we firstly recommend Upwind scheme model , and secondly Papageorgiou's model that performed will to represent traffic flow in tests as candidate models for further development of simulation model for Naebu expressway in Seoul.
Inherent Random Heterogeneity Logit Model for Stated Preference Freight Mode Choice
KIM, Kang-Soo ;
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 83~92
Freight mode choice models are essential to the analysis of many areas of transport research. However, observations of actual market choices have only been made in a limited number of situations. Therefore, stated preference(SP) techniques have emerged as an alternative source of actual market choices to be used for estimating freight mode choice models. Considerable confidence exists about SP data, but little consideration has been given to the potential for estimation bias. This paper has been motivated by the theoretical side of estimating SP discrete choice models, focusing on a case study of freight mode choice. Recently developed simulation methods are used to construct inherent random heterogeneity legit models, which consider individual heterogeneity, its inheritance to the next choices and overcome the independence from irrelevant alternatives (IIA) property. This Paper contributes to the development of models dealing with heterogeneity and its inheritance, and sheds light on the heterogeneity of freight transport.
An Empirical Analysis of the Aggregate Travel Demands of the Urban Households in Korea
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 93~103
In this paper, a complete system of travel demand equations using almost ideal demand system has been estimated with Korean urban household expenditure data. Demands for the city bus mode, intercity bus mode, taxi mode, train mode, subway mode, gasoline, and other goods and services are estimated by the Zellner's iterative seemingly unrelated regression method. The demand model is used to compute the elasticities of demand for each travel mode with respect to its own price, prices of other modes, and income (expenditure). The results show : (a) the price elasticity of demand for taxi, gasoline, and city bus modes are inelastic in ascending order with the value of -0.57, -0.69, and -0.81, respectively, (b) the price elasticity of demand for subway is unit elastic with the value of -1.00. (c) the price elasticity of demand for intercity bus and train modes are elastic with the value of -1.67 and -1.23 respectively; (d) the cross price elasticities of demand for travel modes are somewhat mixed with and without reason: (e) the income elasticity of demand for gasoline is elastic with the value of 1.72; (f) the income elasticity of demand for intercity bus, taxi, subway, city bus, and train modes are inelastic in descending order with the value of 0.03, 0.14, 0.29, 0.40. and 0.49. respectively.
A Method for Pedestrian Accident Reconstruction Using Optimization
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 105~113
As the number of pedestrian accident increases, the reconstruction of an accident becomes important to find the source of the fault. Generally, accidents are reconstructed by the intuition of experts or primitive physics. A reconstruction method is proposed using sophisticated optimization technology. At first, a dynamic simulation model is established for the accident environment. Occupant analysis for automobile crashworthiness is employed. The situation before an accident is identified by optimization. The impact velocity and the position of the pedestrian are utilized as design variables. The design variables are found by minimizing the difference between the simulation and the real accident. The optimization process is performed by linking an occupant analysis program MADYMO to an optimization program VisualDOC. Since the involved analysis is dynamics and highly nonlinear, response surface method is selected for the optimization process. Problems are solved for various situations.
Development of a Dynamic Offtracking Model on Horizontal Curve Sections (Based on Articulated Vehicles)
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 115~128
Dislike the tangent sections, the horizontal curve sections of roads should be designed, considering several factors : one of such factors is widening. In other words, since widening results from that when a vehicle runs on the horizontal curve sections, the rear wheels of the vehicle run not along with tracks of the front wheels but out of that, such offtracking should be exactly investigated and reflected in design of the curve sections. Especially in the case of industrial roads which semi-trailers and large trucks run frequently or arterial roads with small curve radiuses in mountainous regions. serious offtracking Phenomenons result in increasing the risk of accidents. decreasing the capacities and jeopardizing pedestrians' safety on the curve sections. For the offtracking, widening amounts of roads has been determined under the traditional presumption that vehicles run at a low speed and there is no superelevation. In fact, however, since the vehicles run at a high speed as well as at a low speed and the superelevation is installed on the horizontal curve sections in the structural aspect of roads, the existing standards for installing widening have a limitation to reflect exactly actual Phenomenons. In particular, for articulated wheel axles of a tractor and a trailer and long articulated vehicles, not only the offtracking degree is very high but also the interpretation shows different aspects from one of single axles. Comparing and reviewing the results of Korean and foreign studies related to the trailer offtracking model theory and the standards for installing widening, this study developed a realistic dynamic offtracking model which considers geometric structures of roads and speeds of vehicles, suggested how to measure widening with this model and examined applicability of the model. The findings of this study are as follows ; First. a dynamic offtracking model. which considers dynamic movements of a tractor and a trailer and the superelevation, was developed. Second, a new method to measure widening with the developed dynamic offtracking model was developed and a method to measure widening with swept path width was suggested as well. Finally, validity of the current standards for installing widening was examined by determining actual offtracking and widening amounts with the developed model and the applicability was investigated through the case studies. Compared with the existing offtracking models, the dynamic offtracking model developed in this study can reflect practically vehicle speed. dimension and geometric structural aspects of roads. In conclusion, the meaning of this study is that it reviews validity of the current standards for installing widening and provides a base to establish such standards by suggesting new methods to measure the widening with this dynamic offtracking model.
An Equality-Based Model for Real-Time Application of A Dynamic Traffic Assignment Model
Shin, Seong-Il ; Ran, Bin ; Choi, Dae-Soon ; Baik, Nam-Tcheol ;
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 129~147
This paper presents a variational equality formulation by Providing new dynamic route choice condition for a link-based dynamic traffic assignment model. The concepts of used paths, used links, used departure times are employed to derive a new link-based dynamic route choice condition. The route choice condition is formulated as a time-dependent variational equality problem and necessity and sufficiency conditions are provided to prove equivalence of the variational equality model. A solution algorithm is proposed based on physical network approach and diagonalization technique. An asymmetric network computational study shows that ideal dynamic-user optimal route condition is satisfied when the length of each time interval is shortened. The I-394 corridor study shows that more than 93% of computational speed improved compared to conventional variational inequality approach, and furthermore as the larger network size, the more computational performance can be expected. This paper concludes that the variational equality could be a promising approach for real-time application of a dynamic traffic assignment model based on fast computational performance.
Development of A Network loading model for Dynamic traffic Assignment
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 149~158
For the purpose of preciously describing real time traffic pattern in urban road network, dynamic network loading(DNL) models able to simulate traffic behavior are required. A number of different methods are available, including macroscopic, microscopic dynamic network models, as well as analytical model. Equivalency minimization problem and Variation inequality problem are the analytical models, which include explicit mathematical travel cost function for describing traffic behaviors on the network. While microscopic simulation models move vehicles according to behavioral car-following and cell-transmission. However, DNL models embedding such travel time function have some limitations ; analytical model has lacking of describing traffic characteristics such as relations between flow and speed, between speed and density Microscopic simulation models are the most detailed and realistic, but they are difficult to calibrate and may not be the most practical tools for large-scale networks. To cope with such problems, this paper develops a new DNL model appropriate for dynamic traffic assignment(DTA), The model is combined with vertical queue model representing vehicles as vertical queues at the end of links. In order to compare and to assess the model, we use a contrived example network. From the numerical results, we found that the DNL model presented in the paper were able to describe traffic characteristics with reasonable amount of computing time. The model also showed good relationship between travel time and traffic flow and expressed the feature of backward turn at near capacity.
Development of an Average Green Time Estimation Model for Proper Evaluation of Traffic Actuated Operation
KIM, Jin Tae ; CHANG, Myungsoon ; SON, Bongsoo ; DOH, Tcheol Woong ;
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 159~168
The Highway Capacity Manual(HCM) suggests estimating the average green time for the performance evaluation of the traffic actuated operation and Provides the average green time estimation model. However, the model provides with much room for improvements. This document proposes a new analytical model that overcomes the shortage of the HCM model. The average green times estimated by the HCM model and the proposed model were compared. A computer program using the proposed model was coded for the study, while the ACT348 program was used for the implementation of the HCM model Through the comparison study based on the 1,196 hypothetical simulation data surrogating field data, it was found that the average green times estimated by the proposed model yields much nicer one-to-one linear relationship to the simulation results than the ones from the HCM model in both exclusive-only and shared-permitted cases. The R2 values of the proposed and the HCM models with those cases are 0.90 and 0.56, and 0.86 and 0.57, respectively.
A case study on the establishment of pedestrian crossing
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 179~192
Corridor Control Strategies of Traffic Adaptive Control System in Seoul
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 193~207
A Study on the Measurement of Development Benefits for the Restoration in Urban Railway Projects
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 211~211
Design of driver's workload prediction model through virtual AHS simulator development
Journal of Korean Society of Transportation, volume 20, issue 3, 2002, Pages 212~212