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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
Selecting the target year
Analysis of stable flow traffic characteristics to develop spatial distribution models for freeway-diverging sections
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 9~22
Merging and Diverging sections are critical to the operation of a freeway because of vehicles trying to enter(or exit) the freeway create a demand for space and the complexity or the interactions, thus are a major causing turbulence areas in these sections. An analysis of traffic characteristics in these sections is very important because ramp merging and/or diverging flow affects overall freeway sections. Most of the research like HCM model have been devoted to macroscopic analysis which treated operational analysis procedures, but the lack of detailed microscopic study on vehicle movement has limited capability in the explanation of restrictive vehicular conflicts. This study deals with a methodology to determine the operation of freeway-diverging section. based on a microscopic analysis on a lane-by-lane basis. Also the Spatial Distribution Model that estimates point flows at various upstream locations of an off-ramp in freeway lanes was developed. In this research the previous studies(KHCM, USHCM 2000, California method) were compared with the model developed here. It was found that the operation of ramp junctions controls not only lane 1 (which is used as the main element in the existing ramp procedures) but also other two lanes of freeway. The results of the methodology indicate superiority over the existing capacity or level of service analysis method for ramp junctions. Limitation of the model presented is related to the data base consisted of only one 3-lane section freeway. An additional investigation and further comparative study should be shown on collecting and analyzing data for 2-lane, as well as for 4-lane.
Saturation Headway of Through Movement at Signalized Intersections in Urban Area
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 23~31
The headway of vehicles entering an intersection is closely related with the saturation flow rate and is a basic parameter required for determining the saturation headway and the start-up lost delay. Since such headway value reflects the drivers' behaviors and features of the intersection, all intersections don't have an equal value, but are affected by number and location of their lanes, changing types, local characteristics and time zone. Accordingly, this study attempted to suggest proper values on the basis of data by investigating headway in lanes. Number of exclusive through lanes was divided into single lane, double lanes and triple lanes, the locations of lanes were divided into inside lane, central lane and outside lane. As a result of investigating the headway, single through lane, double through lanes-inside lane, and triple through lane-outside lane showed as 1.73 sec., 1.71 sec. and 1.93sec., respectively. The result of calculating the area factor of business areas by fixing 1.00 for the residental area and applying relation between headway and saturation flow rate was 0.96. In the case of start-up lost delay lead dual left turn and directional separation were 1.41 sec. and 3.27 sec., respectively, showing the great difference. Therefore, different start-up lost delay according to changing type should be applied.
Analysis of the Effects of Radio Traffic Information on Urban Worker's Travel Choice Behavior
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 33~43
Travel choice behavior is affected by real-time traffic information. Recently, in urban area, real-time traffic information is provided by several instruments such as transportation broadcasting, internet PC network and variable message sign, etc. Furthermore, it has been increasing for urban travelers to use real-time traffic information provided by several instruments. The purpose of this study is to analyze the effects of advanced traveler information on urban worker's travel choice behavior. Among several Advanced Traveler Information System(ATIS) employed in urban area. This study focuses on examining the effects of transportation broadcasting on urban worker's travel choice behavior. This study attempts to examine traveler's mode change behavior in the pre-trip stage and traveler's route change behavior in the on-route stage. For this study, the survey data collected from Daegu City in 2000 is used. For empirical analysis, several nested logit models are estimated, and among them, the best models are reported in this paper. Furthermore, based on the empirical models estimated for this research, important findings and their policy implications are discussed.
The Analysis of Priorities of Roads Investment Using Analytic Hierarchy Process
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 45~54
The Analytic Hierarchy Process (AHP) has been widely used as a comprehensive evaluation method since it can include various evaluation standards of both the public and private sectors. It also provides the objective mathematics to process subjective and Personal preferences of an individual or a group in making a decision. This study tried to use AHP to determine the priority of roads investment, considering various effects in a hierarchy such as environmental effects, residential life, and regional development which has not been treated explicitly. As a case study, roads in Gyeongsangbukdo province have been chosen for the evaluation in this research. For the application, it used relative measurements to estimate the weight of upper level structure, and absolute measurement for low level structure instead of pairwise comparisons.
A Study on the Applications of Shielding Theory
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 55~66
In many countries the principle of shielding is employed to permit a more logical approach to restricting new construction and prescribing obstacle marking and lighting. It also reduces the number of cases of new construction requiring review by authorities. Shielding principles are employed when some object, an existing building or natural terrain, already penetrates above one of the obstacle limitation surfaces described in Annex 14. If it is considered that the nature of an object is such that its presence may be permanent, then additional objects within a specified area around it may be permitted to penetrate the surface without being considered as obstacle. The shielding effect of immovable obstacles laterally in final approach and missed approach areas is more uncertain. In certain circumstances, it nay be advantageous to preserve existing unobstructed cross section areas, particularly when the obstacle is close to the runway. This would guard against future changes in either approach or take-off climb area specifications or the adoption of a turned take-off procedure.
A new approach on Traffic Flow model using Random Trajectory Theory
PARK, Young Wook ;
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 67~79
In this paper, observed trajectories of a vehicle platoon are viewed as one realization of a finite sequence of random trajectories. In this point of view, we develop novel and mathematically rigorous concept of traffic flow variables such as local traffic density, instantaneous traffic flow, and velocity field and investigate their nature on a general probability space of a sequence of random trajectories which represent vehicle trajectories. We present a simple model of random trajectories as an illustrative example and, derive the values of traffic flow variables based on the new definitions in this model. In particular, we construct the model for the sequence of random vehicle trajectories with a system of stochastic differential equations. Each equation of the system nay represent microscopic random maneuvering behavior of each vehicle with properly designed drift coefficient functions and diffusion coefficient functions. The system of stochastic differential equations nay generate a well-defined probability space of a sequence of random vehicle trajectories. We derive the partial differential equation for the expected cumulative plot with appropriate initial conditions. By solving the equation with numerical methods, we obtain the values of expected cumulative plot, local traffic density, and instantaneous traffic flow. In addition, we derive the partial differential equation for the expected travel time to a certain location with appropriate initial and/or boundary conditions, which is solvable numerically. We apply this model to a case of single vehicle trajectory.
Development of a Bi-objective Cycle-free Signal Timing Model Using Genetic Algorithm
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 81~98
This paper documents the development of a bi-objective(minimizing delays and Queue lengths) cycle-free signal timing length model using Genetic Algorithm. The model was embodied using MATLAB. the language of technical computing. A special feature of this model is its ability to concurrently manage delays and queue lengths of turning movement concurrently. The model produces a cycle-free signal timing(cycles and green times) for each intersection on the cycle basis. Appropriate offsets could be also accomplished by applying cycle-free based signal timings for respective intersections. The model was applied to an example network which consists of four intersections. The result shows that the model produces superior signal timings to the existing signal timing model in terms of managing delays and queue lengths of turning movements.
Development of a Lane Changing Model Yielding Reallstic Lane Usage
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 99~111
During the last decade, a simulation study has become a critical component of a traffic analysis. A simulation model considers different aspects of drivers' behavior and consists of two major theories in terms of vehicle dynamics car-following and lane-changing models. While the car-following theory has found its theoretical foundation through robust studies, the lane-changing theory remains in the primitive stage. This document describes a new lane-changing model developed based on the one used in the Freeway Simulation(FRESIM) model. The FRESIM model is the one developed over two decades by many traffic engineers under the supervision of the Federal Highway Administration in the United States. It has been indicated that the FRESIM model provides unrealistic lane usage due to its lane-changing model. It was found from the field data that the minimum headway allowing the lane-changing maneuver is 1.34 seconds and that the lane-changing-time period and the free-flow speed follow F and Normal distributions, respectively. A new model includes a new lane-changing motivation that a front vehicle changes the lane when pressure is loaded to a driver due to the high cruising speed of a following vehicle and when an adjacent lane provides comfort-driving environment. A simulation model with the proposed lane-changing model introduces realistic lane utilization comparable to the field data at 95% confidence level.
Dynamic Network Loading Model based on Moving Cell Theory
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 113~130
In this paper, we developed DNL(Dynamic Network Loading) model based on Moving cell theory to analyze the dynamic characteristics of traffic flow in congested network. In this paper vehicles entered into link at same interval would construct one cell, and the cells moved according to Cell following rule. In the past researches relating to DNL model a continuous single link is separated into two sections such as running section and queuing section to describe physical queue so that various dynamic states generated in real link are only simplified by running and queuing state. However, the approach has some difficulties in simulating various dynamic flow characteristics. To overcome these problems, we present Moving cell theory which is developed by combining Car following theory and Lagrangian method mainly using for the analysis of air pollutants dispersion. In Moving cell theory platoons are represented by cells and each cell is processed by Cell following theory. This type of simulation model is firstly presented by Cremer et al(1999). However they did not develop merging and diverging model because their model was applied to basic freeway section. Moreover they set the number of vehicles which can be included in one cell in one interval so this formulation cant apply to signalized intersection in urban network. To solve these difficulties we develop new approach using Moving cell theory and simulate traffic flow dynamics continuously by movement and state transition of the cells. The developed model are played on simple network including merging and diverging section and it shows improved abilities to describe flow dynamics comparing past DNL models.
Grouping method on functional classification for national highway
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 131~144
The road grouping is a method to group the road links having similar features. The traditional road grouping method assuming the number of groups at the beginning stage can involve analysts' subjective judgement in analysis. Furthermore, the theoretical concept behind the method is usually unclear. This paper presents a new methodology in order to improve an existing road grouping method. Also, we investigate traffic volume data acquired from 294 permanent surveying locations in the national highway for the verification of the methodology which is presented newly. This research introduces more variables into the traditional grouping method by using factor analysis. The additional traffic variable in the proposed method are : Annual Average Daily Traffic (UDT), K1000 Summation Value(
K1000), heavy vehicles proportion, and day-night volume proportion. We find that the new method can identify more detailed groups than the existing methods. Also the national highway functional classification was possible in case of other traffic variables applied in new grouping methodology. The national highway are classified into five groups: (1)region industrial road group. (2)area arterial road group, (3)metropolis circumference road group. (4) small & medium city circumference-sightseeing road group and (5) sight-seeing road group. In this research, the analysis has been conducted using traffic volume-related variables for national highway. Developing a more complex and complicated grouping methodology of road sectors is reserved for future research.
A Queue Length Prediction Algorithm using Kalman Filter
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 145~152
Real-time queueing information and/or predictive queue built-up information can be a good criterion in selecting travel options, such as routes, both for users, and for operators in operating transportation system. Provided properly, it will be a key information for reducing traffic congestion. Also, it helps drivers be able to select optimal roues and operators be able to manage the system effectively as a whole. To produce the predictive queue information, this paper proposes a predictive model for estimating and predicting queue lengths, mainly based on Kalman Filter. It has a structure of having state space model for predicting queue length which is set as observational variable. It has been applied for the Namsan first tunnel and the application results indicate that the model is quite reasonable in its efficacy and can be applicable for various ATIS system architecture. Some limitations and future research agenda have also been discussed.
Multiple User Class Traffic Assignment based on Variational Inequality Formulation in Variable demands
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 153~161
Multiple User Class Assignment(MUCA) problem is for loading a travel demand on the road network in the case that the network consists of several classes of road users. MUCA might relax the strong assumption that all travellers have the same travel behavior along with that it can, to some extent, consider heterogeneous behaviors within the model. However, due to its asymmetric properties of travel cost function. MUCA has been known that it is difficult to formulate and to solve. Based on variational inequality problem, this paper presents a formulation with considering elastic demand patterns and its solution algorithm. This paper also provides equivalency condition of the model and numerical experiments with a simple example network.
Development of Speed Measurement Accuracy Using Double Loop Detectors
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 163~174
Speeding has been reported as one of the major causes for fatal traffic accidents in Korea. The resolution against this dangerous speeding comes to make the automated speed enforcement system an enforcement tool. The speed detection device, which measures speeds of each incoming vehicles using double loop sensors, requires high accuracy. The object of this study is to develop an accurate speed measurement algorithm using double loop detectors. Some important findings are summarized as follows: 1) It was found that speed measurement errors are caused by scanning rate, distance of two loops, irregular vehicle trajectories, multiple vehicles in detection zone. 2) A proposed algorithm using two signal set proved to reduce variance as well as mean of speed measurement. 3) A proposed filtering algorithm was effective to filter irregular driving vehicles and multiple vehicles in detection zone. A comprehensive field test of developed algorithm resulted in significant improvement of speed measurement accuracy.
A Study on Bus Arrival Information for BIS
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 175~181
BIS(Bus arrival Information System) is a system that informs Passengers waiting at bus stops of the bus arrival time of next buses. However, when operating this system, it is not exactly known what type of bus arrival information should be provided. The purpose of this paper is to develop a model of the optimal bus arrival time to be informed for BIS. Analyzing Efficiency in the Seoul's Urban Bus Industry Using Data Envelopment Analysis. Two basic types of bus arrival information can be considered. One is Bus Locations : Where next buses are located and under what situation they are, such as the next bus departed from the previous stop, The other is Expected Arrival Time. Time to the arrivals of next buses. Characteristics of these two types of bus arrival time information provided for passengers waiting at bus stops for BIS are examined. The waiting time of passengers at bus stops is derived as a function of the bus arrival time to be informed. Some basic principles about the optimal bus arrival time to be informed are found. Finally, a case study assuming several simplifications is performed. One of the key findings is that there exists optimal arrival time to be informed other than the average arrival time. The optimal arrival time to be informed should be closer to the average arrival time for small and very large standard deviations and be earlier for certain amounts of standard deviations.
Development of Route Choice Behavior Analysis Simulator Under Various ATIS Environment
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 183~191
This paper is aimed at presenting a new simulator for acquiring drivers' route choice behavioral data to evaluate various ATIS(Advanced Traveler Information System) in controlled laboratory. Although questionnaires based stated preference surveys have been widely used in this field, they suffer from the difficulty in making respondents fully understand complex scenarios in questionnaires and feel travel time pressure of the scenarios. Therefore, the obtained data can be depreciated. The simulator is a good alternative to resolve this since it can create more realistic understanding on the traffic situations. A prototype simulator with three modules has been developed. To verify the validity of it, a pilot test was performed for a small real network, and its data was analyzed with a discrete choice model, The result was reasonably acceptable. The simulator can be very effective for developing and evaluating different information strategies, prior to as well as posterior to major investments
Development of A System Optimum Traffic Control Strategy with Cell Transmission Model
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 193~206
A signal optimization model is proposed by applying the Cell-Transmission Model(CTM) as an embedded traffic flow model to estimate a system-optimal signal timing plan in a transportation network composed of signalized intersections. Beyond the existing signal-optimization models, the CTM provides appropriate theoretical and practical backgrounds to simulate oversaturation phenomena such as shockwave, queue length, and spillback. The model is formulated on the Mixed-Integer Programming(MIP) theory. The proposed model implies a system-optimal in a sense that traffic demand and signal system cooperate to minimize the traffic network cost: the demand departing from origins through route choice behavior until arriving at destinations and the signal system by calculating optimal signal timings considering the movement of these demand. The potential of model's practical application is demonstrated through a comparison study of two signal control strategies: optimal and fixed signal controls.
A Study on the Efficiency of Multi-Legged Intersection Through Sensitivity Analysis (Based on the Four or Five Legged Intersection)
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 217~230
A study on testing the ability of Vehicle Detection System in ATMS
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 231~244
A GIS-based Traffic Accident Analysis on Highways using Alignment related Risk Indices
Journal of Korean Society of Transportation, volume 20, issue 5, 2002, Pages 247~248