• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.102-115
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• 2016

In this study, a scheme of ramp metering that uses Off-ramp Exit Percentage instead of the O/D table required for systems of integrated control of ramps at the target freeway segment is presented. The segment from Gyeyang IC to Jangsu IC on the Seoul Outer Ring Expressway was selected for the study because the segment frequently shows large volume of traffic on the short distance between the two ICs requiring an integrated on-ramp control by taking the traffic situation on an entire expressway into account despite an unavailability of O/D data. Thus the information of Off-ramp Exit Percentage at each IC were collected instead of securing the O/D table through actual survey, and the congestion on the segment was analyzed to identify the validity of the use of off-ramp traffic instead of O/D data. In addition, the scheme of ramp metering that exploits the off-ramp traffic information was prepared through simulations conducted in a way supporting the traffic control for respective access roads thereof by taking traffic situations and queues on each ramp into account. The results obtained from the simulation analyses revealed an improved level of travel speed and traffic volume on the main line and validated the use of off-ramp traffic instead of the O/D table for the ramp metering.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2031-2042
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• 2017

In this paper, a novel traffic flow control method based-on ramp metering and speed regulation using an adaptive sliding mode control (ASMC) method along with a deadzoned parameter adaptation law is proposed at a stochastic macroscopic level traffic environment, where the influence of the density and speed disturbances is accounted for in the traffic dynamic equations. The goal of this paper is to design a local traffic flow controller using both ramp metering and speed regulation based on ASMC, in order to achieve the desired density and speed for the maintenance of the maximum mainline throughput against disturbances in practice. The proposed method is advantageous in that it can improve the traffic flow performance compared to the traditional methods using only ramp metering, even in the presence of ramp storage limitation and disturbances. Moreover, a prior knowledge of disturbance magnitude is not required in the process of designing the controller unlike the conventional sliding mode controller. A stability analysis is presented to show that the traffic system under the proposed traffic flow control method is guaranteed to be uniformly bounded and its ultimate bound can be adjusted to be sufficiently small in terms of deadzone. The validity of the proposed method is demonstrated under different traffic situations (i.e., different initial traffic status), in the sense that the proposed control method is capable of stabilizing traffic flow better than the previously well-known Asservissement Lineaire d'Entree Autoroutiere (ALINEA) strategy and also feedback linearization control (FLC) method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.579-585
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• 2009

In spite of the proven effectiveness of ramp metering system, it has not been successfully implemented in Korean setting. The purpose of this paper is to select target locations to introduce ramp metering into the Korean expressway system. For this, domestic standards to introduce ramp metering have been presented after reviewing those of the US. The major criteria are level of service (LOS), the existence of detour route, space for queue build-up and opened ramp. 15 different locations were selected and AHP has been used to make priority among them. Intuitively, the result of priority was in accordance with the congestion and traffic volume. The core results identified in this paper is expected to be used in different cities and expressway networks elsewhere.

• Proceedings of the KOR-KST Conference
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• 1998.09a
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• pp.152-159
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• 1998

This paper presents a method evaluating benefits of ramp metering strategies on freeway safety. Based on the traffic and the accident data collected on a 4.2 km (2.6 mile) section of Interstate highway 35-West in Minneapolis, U.S.A., the relationship between traffic variables and safety measures is investigated. An aggregate specification that could be used to predict accident frequencies on freeways is proposed as a multiple regression form. The specification includes 15 minutes volume and occupancy data, which are commonly available from surveillance and control systems. The primary variables that appear to affect the frequencies of freeway accident are: vehicle-miles of travel, entrance ramp volumes and the dynamic effect of queue building. A simulation method evaluating the dynamic effect of control strategies on safety is proposed next. The potential benefits of freeway ramp metering on freeway safety are finally investigated via a proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.84-92
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• 2006

Freeway Corridors consist of urban freeways and parallel arterials that drivers can use alternatively. Ramp metering in freeways and signal control in arterials are contemporary traffic control methods that have been developed and applied in order to improve traffic conditions of freeway corridors. However, most of the existing studies have focused on either optimal ramp metering in freeways, or progression signal strategies between arterial intersections. There have been no traffic control systems in Korea that integrates the freeway ramp metering and arterial signal control. The effective control strategies for freeway operations may cause negative effects on arterial traffic. On the other hand, traffic congestion and bottleneck phenomenon of arterials due to the increasing peak-hour travel demand and ineffective signal operation may generate an accessibility problem to freeway ramps. Thus, the main function of the freeway which is the through-traffic process has not been successful. The purpose of this study is to develop an integrated control model that connects freeway ramp metering systems and signal control systems in arterial intersections. And Optimization of integrated control model which consists of ramp metering and signal control is another purpose. Optimization results are verified by comparison with the results from MATDYMO.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.8-15
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• 2007

Freeway corridors consist of urban freeways and parallel arterials that drivers can use alternatively. Ramp metering in freeways and signal control in arterials are contemporary traffic control methods that have been developed and applied in order to improve traffic conditions of freeway corridors. However, most of the existing studies have focused on either optimal ramp metering in freeways, or progression signal strategies between arterial intersections. There have been no traffic control systems in Korea that integrates the freeway ramp metering and arterial signal control. The effective control strategies for freeway operations may cause negative effects on arterial traffic. On the other hand, traffic congestion and bottleneck phenomenon of arterials due to the increasing peak-hour travel demand and ineffective signal operation may generate an accessibility problem to freeway ramps. Thus, the main function of the freeway which is the through-traffic process has not been successful. The purpose of this study is to develop an integrated control model that connects freeway ramp metering systems and signal control systems in arterial intersections. And Optimization of integrated control model which consists of ramp metering and signal control is another purpose. The design of experiment, neural network, and simulated annealing are used for optimization.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.5
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• pp.533-536
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• 2014

In this paper, a near optimal decentralized observer-controller design method is proposed for ramp metering systems based on SDRE (State Dependent Riccati Equation) approach. The optimal nonlinear observer gain is parameterized in terms of the solution matrix of an SDRE. This paper gives a simple algorithm to compute the near optimal observer gain. The optimal control design problem is also considered. Finally, numerical simulation results are given to illuminate the effectiveness and practicality of the proposed design method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.649-656
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• 2011

The increase in the traffic demand and behavioral pattern of its use reached the limit for the only means of road construction to bear; thus the multilateral efforts to find a solution to this problem together with the examination and research on this issue, among which the most representative strategy is Ramp Metering System controlling access traffic volume to connection roads. The operation standard and running time was re-established in consideration of geographical conditions and traffic circumstances by considering the standard of operation and running time of the currently operated Jangsu- Jungdong section of the outer ring expressway of Seoul. For this purpose, this research analyzed the operative standard of RMS home and abroad and suggested a new operative standard of ramp metering through the analysis of break points.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1996.10a
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• pp.180-183
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• 1996

This work discusses simulation results for the fuzzy logic controller tested the project“Fuzzy Ramp Metering Algorithm Implementation.”The performance objectives were, in order of priority, to maximize total vehicle-miles, maximize mainline speeds, and minimize delay per vehicle while maintaining an acceptable ramp queue. In the fuzzy logic controller, the sensors from the on-ramps were helpful in maintaining reasonable ramp queue and mainline congestion because it considered these factors simultaneously. Each metered ramp had a parameter input file, which allowed the controller to be modified without recompiling the software. Consequently, maintenance costs should be minimal.

• 한국도로학회:학술대회논문집
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• 2008.03a
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• pp.103-111
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• 2008