• Journal of Korean Society of Transportation
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• v.25 no.2 s.95
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• pp.63-72
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• 2007

The purpose of this study is to develop a traffic characteristic analysis, a correlation analysis with the variables of traffic characteristics, and accident estimation models while recognizing the seriousness of the traffic accidents. The analyses deal with the 181 4-legged signalized intersections that accounted for 1,183 out of 3,115 accidents in Cheongju in 2004. After measuring ADT, intersection area, average lane width, elevation, and other items as independent variables and the number of traffic accidents, the traffic accident rate (accidents per million entering vehicles) and equivalent property damage only (EPDO) figures as dependent variables which are estimated as influencing signalized intersection accidents, the estimation models are developed using correlation analysis and multiple regression analysis. In the analysis of the number of traffic accidents, the model indicates an $R^2$ of 0.612, and five independent variables are taken as significant factors. In the analysis of traffic accident rates, the model indicates an $R^2$ of 0.304 and five significant factors, including intersection area and ADT. Also, for the analysis or the EPDO numbers, which coincides with understanding the seriousness of the traffic accidents and the traffic characteristic analysis, the model indicates an $R^2$ of 0.559, and four independent variables (ADT, main street average lane width, elevation, and speed limit) as significant factors.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2908-2914
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• 1998

This paper presents an intelligent signal for controling the traffic lights on traffic junction network with dynamic traffic flow, When a junction is connected to adjacent junctions on four sides. Prior researches have been done on the single traffic junction. However, it is dificult to apply single junction controller to real traffic situation. In this paper, we develop a fuzzy taffic network controller which adjusts the extension time of current green phase by using teh fuzzy input variables such as the number of entering cars at the green light, the number of waiting cars during the red light, and the traffic volume. The proposed method was compared to the existing junction signal control methods on controllers in terms of average delay time of cars and the cost function defined in this paper.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.53-66
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• 2017

In order to improve traffic flow and vehicular safety, installation of roundabouts is encouraging recently. Roundabouts are generally installed at which traffic flow and pedestrian flow is relatively low intersections. Roundabouts reduce vehicle speed, minimize vehicle weaving, and reduce critical conflict points. For these reasons, roundabouts are generally operated unprotected pedestrian crosswalk, thus a shortcoming for pedestrian safety always exists at roundabouts. The purpose of this study is developing a dynamic signal metering algorithm for traffic and pedestrian at four-way-approach with two-lane roundabouts in which three different operation algorithms(fixed-time pedestrian, vehicle signal metering, and vehicle and pedestrian signal metering) are suggested and its performance is tested by using VISSIM. The results of the fixed pedestrian signal operation show that there is a big average delay increase in general and that increases up to 51.4 seconds/vehicle(42.5%) when the total number of approaching vehicle is 3,800 vehicle/hour. However, the results of the simultaneous dynamic signal metering operation for the vehicle and pedestrian crossing with push button show that there is a substantial average delay reduction up to 40.6 seconds/vehicle(42.7%) when the total number of approaching vehicle is 3,000 vehicle/hour.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.29-37
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• 2017

Intersection signal's phase time is calculated and determined by car and pedestrian traffic volume. If signal phase time and traffic volume dis-matched, cars and pedestrians have much delay time. This paper suggested an All-Red phase application method that cars and pedestrians securing safety and minimizing traffic signal waiting time. The key solution of this suggested method is determining All-Red phase operation by using sum of spare green time that have no passing cars. That is, total time of spare green time that have no passing cars is longer than All-Red phase time, operating All-Red phase has an effect. And case study carried out at the signalized intersection, revealed that this suggested method has much effectiveness.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.121-128
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• 2009

This study has proposed the signal operating system to use both semi-actuated signal control and pedestrian push-button as a way to make up for the problems of 3 leg intersections which are operated inefficiently in the signal operation, one of the methods of traffic operations. In case of the semi-actuated signal control, it can reduce delay inside the intersection by serving to uncongested traffic on the main road where there is not much traffic volume on the secondary road and push-button signal can reduce unnecessary waiting time it could happen to vehicles by operating it though there is no pedestrian. Quantitative analysis was tried regarding the average delay reduction per vehicle using VISSIM, microscopic simulation program regarding how much effect it has compared with the existing signal control system and semi-actuated signal control system when the above two advantages are collected. The field test was performed for one three-leg intersection of Incheon. According to respectively signal control method pedestrian traffic changed and executed a sensitivity analysis. The result which compares the average delay time per a vehicle of scenarios, the signal control method of using the pedestrian push-button system in comparison with the fixed signal control method showed to decrease effect of a minimum 3.7 second (10%), a maximum 5.8 second (16%). When the pedestrian traffic volume was 20% or less of the measurement traffic volume, The signal control method of using the pedestrian push-button system appeared to be more efficient the semi-actuated signal control with object intersection.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.5
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• pp.105-112
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• 2011

Delay reduction of vehicles at the intersection is highly dependent on the signal operation method. Improper traffic operation causes the violation of the traffic regulations and increasing traffic congestion. Delay because of congestion has contributed to the increase in carbon dioxide in the atmosphere. The focus of this paper is to measure the amount of carbon dioxide when the intersection is changed to roundabout. Even though, Intergovernmental Panel on Climate Change(IPCC) recommends Tier 1 method to measure the amount of greenhouse gas from vehicles, this paper used Tier 3 method because we could use the data of average running distance per each vehicle model. Two signalized intersections were selected as the study area and the delay reductions of roundabout operation were estimated by VISSIM microscopic simulation tool. The control delay for boksu intersection reduced from 28.6 seconds to 4.4 seconds and the KRIBB intersection sharply reduced from 156.4 seconds to 23.6 seconds. In addition, carbon dioxide for two intersections reduced to 646.5 ton/year if the intersection is changed to roundabout. Future research tasks include testing the experiment for networks, as well as for various intersection types.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.14-34
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• 2023

The purpose of this study was to calculate the appropriate yellow-signal time for intersections, to find out the relationship between the approach speed and intersection width when calculating the time, and to secure safety by minimizing conflicts and dilemma sections in intersections that change according to the signal operation. For this purpose, 6,824 data points from 5 intersections were collected and analyzed. The main results of the study are as follows. First, the approach speed of individual vehicles in different lanes was analyzed, and the width of an intersection was defined by considering the conflict in each direction. Second, we developed a multiple regression model based on the approach speed and conflict points, which compensated for the problems of an existing formula. Third, a standard table is presented for applying the appropriate yellow-signal time according to the approach speed and intersection width based on a development formula. A method is also presented to determine the safety of the length of the dilemma according to the change in the yellow-light time by presenting a calculation table that can cross-analyze the yellow-signal time and a dilemma section using the relationship.

• Journal of Korean Society of Transportation
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• v.29 no.5
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• pp.157-167
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• 2011

Many problems, such as unexpected delay and collision with pedestrians or vehicles, occur generally at signalized intersections where bicycle users are frequently involved. These problems have hindered bicycle users from riding bicycles on urban highways. The aim of this study is to suggest proper traffic signal operation methods for safe and convenient highway crossing of bicycles. Three types of crossing methods at signalized intersections are proposed and analyzed: (1) indirect left turn, (2) direct left turn on an exclusive bicycle lane, and (3) direct left turn on a bicycle box. The VISSIM simulation tests were conducted based on fifty-four operation scenarios prepared by varying vehicle and bicycle traffic volumes. Both delay and the number of stops are used as the measures of effectiveness in the analysis. The results from the three-legged signalized intersections suggested that (1) the indirect left turn is appropriate when vehicle demand is high while bicycle demand is not, (2) direct left turn on an exclusive bicycle lane is appropriate when both vehicle and bicycle demands are high, and (3) direct left turn on a bicycle box is appropriate when both vehicle and bicycle demands are light.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.115-131
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• 2022

Carbon dioxide (CO₂) emissions from the transportation sector in South Korea accounts for 16.5% of all CO₂ emissions, and road transportation accounts for 96.5% of this sector's emissions in South Korea. Hence, constant research is being carried out on methods to reduce CO₂ emissions from this sector. With the emerging use of smart crossings, attempts to monitor individual vehicles are increasing. Moreover, the potential commercial deployment of autonomous vehicles increases the possibility of obtaining individual vehicle data. As such, CO₂ emission research was conducted at five signalized intersections in the Gangnam District, Seoul, using data such as vehicle type, speed, acceleration, etc., obtained from image detectors located at each intersection. The collected data were then applied to the MOtor Vehicle Emission Simulator (MOVES)-Matrix model-which was developed to obtain second-by-second vehicle activity data and analyze daily CO₂ emissions from the studied intersections. After analyzing two large and three small intersections, the results indicated that 3.1 metric tons of CO₂ were emitted per day at each intersection. This study reveals a new possibility of analyzing CO₂ emissions using actual individual vehicle data using an improved analysis model. This study also emphasizes the importance of more accurate CO₂ emission analyses.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.5
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• pp.45-58
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• 2021

It is generally known that a two-lane roundabout has some problems in safety such as increasing conflicts, typically merging and diverging conflicts and conflicts between entering traffic and exiting as well as turning traffic. To solve these problems, a turbo-roundabout had been developed and has successfully brought safer and more efficient operation in other countries. In this study, micro simulations using VISSIM were conducted to investigate the maximum value of service traffic volume. It was found that operation of turbo-roundabouts was influenced by traffic volume for each turning traffic, and the maximum values of traffic volume were values between 2,400 and 2,800 vehicles per hour as rates of traffic volume for each turning traffic. Typically, turbo-roundabouts have limited to operate in conditions with more than 30% for left-turning traffic volume.