• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.33-42
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• 2007

This research proposes strategies about providing detour route information and traffic management for flood disasters. Suggested strategies are based on prevention and preparation concepts including prediction, optimization, and simulation in order to minimize damage. Specifically, this study shows the possibility that average travel speed is increased by proper signal progression during downpours or heavy snowfalls. In addition, in order to protect the drivers and vehicles from dangerous situations, this study proposes a route guidance strategy based on variational inequalities such as flooding. However, other roads can have traffic congestion by the suggested strategies. Thus, this study also shows the possibility to solve traffic congestion of other roads in networks with emergency signal modes.

• Journal of Korean Society of Transportation
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• v.32 no.3
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• pp.280-292
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• 2014

A tram has been the focus of a new public transportation that can solve a traffic jam, decreasing of public transit usage and environmental problem in recent years. This study aims to develop a signal optimization model for considering the traffic signal progression of tram and vehicles, when they are operated simultaneously in the same signalized intersections. This research developed the KS-SIGNAL-Tram model to obtain a minimum tram bandwidth and to minimize a vehicle's delay to perform a tram passive signal priority, it is based on the KS-SIGNAL model and is added to the properties of a tram and it's system. We conducted a micro simulation test to evaluate the KS-SIGNAL-Tram model, it showed that the developed optimization model is effective to prevent a tram's stop on intersection, to reduce a tram's travel time and vehicle's delay.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.131-137
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• 2004

Conventional traffic signal optimization models assume that green intervals for pedestrian crossings are given as exogenous inputs such as minimum green intervals for straight-ahead movements. As the result, in reality, the green intervals of traffic movements may not distribute adequately by the volume/saturation-flow of them. In this paper, we proposed signal optimization models formulated in BMILP to integrate pedestrian crossings into traffic movements under under-saturated traffic flow. The model simultaneously optimizes traffic and pedestrian movements to minimize weighted queues of primary queues during red interval and secondary queues during queue clearance time. A set of linear objective function and constraints set up to ensure the conditions with respect to pedestrian and traffic maneuvers. Numerical examples are given by pedestrian green intervals and the number of pedestrian crossings located at an arm. Optimization results illustrated that pedestrian green intervals using proposed models are greater than those using TRANSYT-7F, but opposite in the ratios of pedestrian green intervals to the cycle lengths. The simulation results show that proposed models are superior to TRANSYT-7F in reducing delay, where the longer the pedestrian green interval the greater the effect.

• Journal of Korean Society of Transportation
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• v.19 no.1
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• pp.115-129
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• 2001

The purpose of this study is to develop a cycle-free signal timing model for minimizing delays based on Third-generation control concept using Genetic Algorithm. A special feature of this model is its ability to manage delays of turning movements on the cycle basis. The model produces a cycle-free based signal timing(cycles and green times) for each intersection to minimize delays of turning movements on the cycle basis. The performance of cycle-free signal timings was evaluated on normal (v/c = 0.7) and oversaturated (v/c=1.0) conditions. The performance measures are throughput and the number of queued vehicles at the end of green time. The result shows that the cycle free signal timing is superior to the fixed signal timing to manage traffic flows of intersections; (1) the proposed model accomplishes the basic objective of the research, producing cycle free signal timings on the cycle basis, (2) on normal conditions, cycle free signal timings produce less queued vehicles at the end of green time, and (3) on oversaturated conditions, the cycle free signal timing is superior to the fixed signal timing to manage saturated traffic flows of intersections.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.75-88
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• 2001

Signal optimization model for alternative use of lanes at a signalized intersection with an stop-line added backward was presented in this paper. The simulation results shot-ed that the traffic fed from the stop-line passed the intersection in each specified phasing interval for left and through traffic. The experimental results indicated that the proposed model was much superior to traditional signal optimization methodology in reducing delay, fuel consumption, and disutility index for delay and stops. The effects for reducing delay were greater than those for doing fuel consumption and disutility index due to the added stop-line. The proposed model is expected to alleviate traffic congestion at intersections, both which have no left turn pocket, and which have large left turn volume. The model is recommended to adapted for intersections spaced long among them with no near driveway.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.617-624
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• 2015

The conflict of opposing pedestrian traffic-flow in a subway station(made up of stair, passageway, and escalator) diminishes the convenience and mobility of its users. In addition, the station's efficiency would be negatively affected by the growth of delay and queue length in pedestrian facilities. As these phenomena have been resulted by the overlapping in pedestrian's traffic-line, the separation of it would alleviate these problems. For the criteria and methodology of separation, this paper has investigated the bi-directional queue length and delay on the entrance of each facility (stair, passageway and escalator). Since the pedestrian flow exists bidirectionally, we have used the weighted average by inflow rate for the delay value. For the optimization of the separation, the Genetic Algorithm has been utilized in order to minimize the delay.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.77-90
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• 2015

An increasing number of vehicles is causing various traffic problems such as chronic congestion of highways and air pollution. Local governments have been managing traffic by constructing systems such as Intelligent Transport Systems (ITS) and Advanced Traffic Management Systems (ATMS) to relieve such problems, but construction of an infrastructure-based traffic system is insufficient in resolving chronic traffic problems. A more sophisticated system with enhanced operational management capabilities added to the existing facilities is necessary at this point. As traffic patterns of the urban traffic flow is time-specific due to the different vehicle populations throughout the time of the day, a local network-wide signal operation plan that can manage such situation-specific traffic patterns is deemed to be necessary. Therefore, this study is conducted for the purpose of establishment of a plan for contextual signal control management through signal optimization at the network level after setting the Frame Signal in accordance to the traffic patterns gathered from the short-term traffic forecast data as a means to mitigate the problems with existing standardized signal operations.

• Journal of Korean Society of societal Security
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• v.1 no.3
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• pp.59-67
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• 2008

The most influential facility causing traffic disaster on the urban road is intersection. Accordingly, this study elected a region for case study from seabang three-way junction, partial section of Dongmoon Ro in Kwang-Ju city, to the intersection of Mudeung Library Entrance. It is believed that the signal progression is very effective on the basis of short interval of intersection and massive traffic volume. The signal progression was simulated by using TRANSYT-7F model. The following is summary of the simulation: According to the change of cycle length, P.I. delay and fuel consumption showed the tendency of being increased in case that cycle length becomes long or short, centering around the best cycle length. In the event of progressing the cycle length, the average speed per vehicle is increased by 11.39Km per hour and P.I value is improved by 40.65% so that it resulted in 42.86% improvement in the total travel time. Moreover, the fuel consumption in line with the progression practice produced fuel saving of 31.04%.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.27-34
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• 2009

The operational effect of traffic signal control improvement was evaluated using the Two-Fluid Model. The parameters engaged in the Two-Fluid Model becomes food indicators to measure the quality of traffic flow due to the improvement of traffic signal operation. A series of experiment were conduced for the 31 signalized intersections in Uijeongbu City. To estimate the parameters in the Two-Fluid Model the trajectory informations of individual vehicles were collected using the CORSIM and Run Time Extension. The test results showed 35 percent decrease of average minimum trip time per unit distance. One of the parameters in the Two-Fluid Model is a measure of the resistance of the network to the degraded operation with the increased demand. The test result showed 28 percent decrease of this parameter. In spite of the simulation results of the arterial flow, it was concluded that the Two-Fluid Model is useful tool to evaluate the improvement of the traffic signal control system from the macroscopic aspect.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.2
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• pp.29-43
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• 2019

The calibration of microscopic traffic simulation models has received much attention in the simulation field. Although no standard has been established for it, a genetic algorithm (GA) has been widely employed in recent literature because of its high efficiency to find solutions in such optimization problems. However, the performance still falls short in simulation analyses to support fast decision making. This paper proposes a new calibration procedure using a dual GA and central composite design (CCD) in order to improve the efficiency. The calibration exercise goes through three major sequential steps: (1) experimental design using CCD for a quadratic response surface model (RSM) estimation, (2) 1st GA procedure using the RSM with CCD to find a near-optimal initial population for a next step, and (3) 2nd GA procedure to find a final solution. The proposed method was applied in calibrating the Gipps car-following model with respect to maximizing the likelihood of a spacing distribution between a lead and following vehicle. In order to evaluate the performance of the proposed method, a conventional calibration approach using a single GA was compared under both simulated and real vehicle trajectory data. It was found that the proposed approach enhances the optimization speed by starting to search from an initial population that is closer to the optimum than that of the other approach. This result implies the proposed approach has benefits for a large-scale traffic network simulation analysis. This method can be extended to other optimization tasks using GA in transportation studies.