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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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Journal DOI :
Korean Society of Transportation
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Volume & Issues
Volume 14, Issue 4 - Dec 1996
Volume 14, Issue 3 - Sep 1996
Volume 14, Issue 2 - Jun 1996
Volume 14, Issue 1 - Mar 1996
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Traffic Flow Characteristics and Model on Multi-lane Roads in Urban Areas
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 7~29
Traffic flow characteristics is analysed on eight multi-lane roads which are unsignalized in urban areas. Data of traffic flow rates by classification and average speed were gathered every ten minutes interval for twenty-four hours. Machine (NC-90A) was used to acquire the field data. The major purpose of this study is to build up speed-density models on urban arterial roads. Five different kinds of models were tested. Those models are Greenshields' model, Greenberg's model, modified Greenberg's model, Underwood's model and Drake's model. The modified Greenberg's model fits best at six points and the Greenshield's model fits best two points out of eight points. The breakpoint(Kb) of modified Greenberg's model is between 10 and 32 pcphpl. Capacity drawn from speed-volume relationships were appeared to be arround 2,000 and 2,200 pcphpl at the Hannam Bridge and the Hannam Overpass and 1,100 and 1,700 pcphpl at Namsan Tunnel(No1) and the beginning point of Gyeong-Bu Expressway.
Evaluation of Residential Street by Pedestrain and Vehicle Occupancy
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 31~44
This study focuses on the evaluation of the streets on residential areas. For this purpose, pedestrain and vehicle occupancy indicators on residential areas are proposed, and vehicle, pedestrain flow and status of on-street parking on residential streets are analyzed. Also, according to the suggested occupancy indicator, occupancy status of pedestrain and vehicle are identified. At the end, evaluation of residential streets are conducted. The suggested occupancy indicator is a quantitative indicator which can represent the traffic situation on street. It can also be represente din the same dimension among pedestrain, vehicle flow, packed vehicle. Also, occupancy indicator can be utilized for the allocation and evaluation of transportation modes on residential street. Except on-street parking during the day time, moving vehicle occupancy rate contains the more than 80 precent when it is estimated based on the vehicle flow and pedestrain only. As the streets on residential area are occupied by the pedestrain approximately 20 percent during the day time, it is identified quantitatively that the necessity of space for pedestrain.
Optimum signal setting based on phase sequence and interval in an isolated intersection
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 45~58
In a large signal intersection, it is the most important to set phase sequences and phase intervals of traffic signal in order to improve the efficiency of the capacity as well as safety. These setting allows to select the best sequence of signal phase among several alternatives, and thus to rearrange the starting and ending points of the individual phase using an effective interphase periods (EIP). The EIP is a gap between previous and current traffic movements at a potential collision point in an intersection. Each of traffic movements has an equality for safety and efficiency at the balanced condition of EIP. This paper presents how to set optimally the phase sequences and intervals of traffic signal in an intersection using phase based approach. And in the second part, we applied the theory developed in the first part. In particular, a numerical example of phase base signal setting is presented using a matrix computation method in order to select the best sequence among several alternatives, and thus to rearrange the starting and ending points of the individual phase using the EIP. This method also allows to apply to optimum signal setting even in five-lag or staggered-type intersection.
A Study on the Loop Detector System for Real-Time Traffic Adaptive Signal Control
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 59~88
This study has determined optimal type, and location of loop detector to measure accurately traffic condition influenced by traffic variation with real time. Optimal type of loop detector for through vehicle at stop bar was determined by confidences of occupancy period, and nonoccupancy period, and so appropriate detector type for application to real time traffic control system has been decided on special loop detector.
shows types and winding methods of existing detector (num1) and special detector (num 7,8) determined. It is desired that optimal location of through loop detector should be installed within 50cm of stop bar owing to vehicle behavior. And optimal location of loop detector for left turn vehicle is determined by left turn vehicle behavior on stop bar. In the case of install only one loop, it is desirable that within 20cm of stop bar. Both the special loop (1.8 × 4.0m : num 1.7) and existing loop (1.8 × 1.8m : num1) would be suitable. A location standard aspects, while regarding as economic, existing loop (1.8 × 1.8m : num1) would be suitable. A location of the queue detector and the spillback prevention detector considering the link length, the pedestran crossing is be or not and the estimation range of queue. And if the link length is shorter than 250m, locations of queue detector and spillback protect detector must be considered in the respect of queue management.
A Development of a Real-time, Traffic Adaptive Control Scheme Through VIDs.
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 89~118
The development and implementation of a real-time, traffic adaptive control scheme based on fuzzy logic through Video Image Detector systems (VIDs) is presented. Through VIDs based image processing, fuzzy logic can be used for a real-time traffic adaptive signal control scheme. Fuzzy control logic allows linguistic and inexact traffic data to be manipulated as a useful tool in designing signal timing plans. The fuzzy logic has the ability to comprehend linguistic instructions and to generate control strategy based on a priori verbal communication. The implementation of fuzzy logic controller for a traffic network is introduced. Comparisons are made between implementations of the fuzzy logic controller and the actuated controller in an isolated intersection. The results obtained from the application of the fuzzy logic controller are also compared with those corresponding to a pretimed controller for the coordinated intersections. Simulation results from the comparisons indicate the performance of the system is between under the fuzzy logic controller. Integration of the aforementioned schemes into and ATMS framework will lead to real-time adjustment of the traffic control signals, resulting in significant reduction in traffic congestion.
A Development of Fuzzy Logic-Based Evaluation Model for Traffic Accident Risk Level
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 119~136
The evaluation of risk level or possibility of traffic accidents is a fundamental task in reducing the dangers associated with current transportation system. However, due to the lack of data and basic researches for identifying such factors, evaluations so far have been undertaken by only the experts who can use their judgements well in this regard. Here comes the motivation this thesis to evaluate such risk level more or less in an automatic manner. The purpose of this thesis is to test the fuzzy-logic theory in evaluating the risk level of traffic accidents. In modeling the process of expert's logical inference of risk level determination, only the geometric features have been considered for the simplicity of the modeling. They are the visibility of road surface, horizontal alignment, vertical grade, diverging point, and the location of pedestrain crossing. At the same time, among some inference methods, fuzzy composition inference method has been employed as a back-bone inference mechanism. In calibration, the proposed model used four sites' data. After that, using calibrated model, six sites' risk levels have been identified. The results of the six sites' outcomes were quite similar to those of real world other than some errors caused by the enforcement of the model's output. But it seems that this kind of errors can be overcome in the future if some other factors such as driver characteristics, traffic environment, and traffic control conditions have been considered. Futhermore, the application of site's specific time series data would produce better results.
Fuzzy Logic Based Modeling of an Incident Detection Algorithm
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 137~155
Estimates of Economies of Scale and Economies of Density in the Ocean Shipping Industry
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 157~172
The long-existed licence system which has acted as one of the strong barriers to entry in the ocean shipping market in Korea is supposed to repeal in the near future. As a result, competition among the different sizes of firms which are operating under regional shield by means of the licence will be intensified. The main objective of this paper is to estimate the degree of economies of scale and economies of density for various firm sizes. For the successful estimation of economies scale and economies of density, translog cost models are developed and estimated through SURE technique which was suggested by Zeller (1963). The major findings are as follows ; All shipping firms in the sample exhibit economies of scale and density. Even small size shipping firms under licence system, they show substantial economies of scale contrary to the wide-known idea that small-size firms are subject to diseconomies of scale. For the ranked firm sizes according to owned deadweight tons, the degree of economies of scale decreases as the firm sizes are larger and larger. The degree of economies of density moderately declines from the smallest to the firm size of 30-60 thousand deadweight tons and sharply rise thereafter. And the large shipping firms with over half-million deadweight tons exhibit high economies density compared to other sizes of firm. If follows that the larger firms have great advantage in competition if the licence system is abolished.
Development of no-overtaking Model and Analysis of fundamentals of traffic flow Characteristics on Two-Lane Highways
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 173~189
Development of Safety-Based Evaluation Model for Two-Way Stop Controlled Intersection
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 191~222
A Study on the Effect of Urban Freeway Traffic Control Strategies on Safety
Journal of Korean Society of Transportation, volume 14, issue 2, 1996, Pages 223~237
Based on the traffic and accident data collected on a 4.2km (2.6mile) section of Interstate highway 35W in Minneapolis the relationship between traffic operation variables and safety measures is investigated. An aggregate specification that could be integrated into an urban freeway safety prediction methodology is proposed as a multiple regression model. The specification includes lane occupancy and volume data, which are the control parameters commonly used because they can be measured in real time. The primary variables that appear to affect the safety of urban freeway are : vehicle-miles of travel, entrance ramp volumes and the dynamic effect of queue building. The potential benefits of freeway traffic control strategies on freeway safety are also investigated via a simulation study. It was concluded that improvement of urban freeway safety is achievable by traffic control strategies which homogenize traffic conditions areound critical occupancy values.