• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.2
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• pp.167-175
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• 2020

The Two-fluid Model, proposed by Herman and Prigogine in 1979, is a macroscopic model for describing network operability in urban networks. Since the Two-fluid Model parameters change according to the traffic flow characteristics, it is necessary to identify the cause of flow change when analyzing the operability using the parameters. This study compared the crash risk according to rainfall using the Two-fluid Model parameters, and explained that the driving behavior affects the operability of the urban network. The results of the parameters estimation showed poor network operation under rainfall condition. The factors of drivers' crash risk perception model were calculated, and driving behavior was analyzed due to crash risk according to rainfall. In both the morning and evening, drivers tended to slow down their speeds to reduce the crash risk, because the risk on rainy days could be high when the speed was the same as on a sunny days. However, the crash risk was still higher on rainy days than sunny. In the future, it is necessary to analyze the relationship between the network operation and the crash risk in various networks and to improve both.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.170-172
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• 2017

표준형 부표류는 2001년에 개발되어 현재까지 15년동안 해상교통환경 및 해양기상여건이 변화하고 관리자의 운영경험이 축적되었으며 최근 첨단 기술 및 신소재가 개발되어 표준형 부표류의 개선이 필요하다. 표준형 부표류의 구조적 및 관리운영적 측면의 현황과 문제점을 분석하고 해양선진국의 사례를 조사하는 등 표준형 부표류를 개발하고 개선하기 위한 연구 개발이 요구된다.

• 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.

• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.37-46
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• 2013

Lane closure in freeway work zone due to maintenance and repair of freeway facilities results in abrupt change of traffic flow. Sudden change of traffic flow results strong interactions among vehicles, and reduces capacity compared to the ordinary traffic condition. Such capacity reduction is likely to cause congestion, traffic queues, and economic loss cost. This study aims to determine the base capacity for a short-term freeway work zone that can be used to establish a work zone schedule in advance without any traffic impact. First, the research collected detector data and schedule data of road works on all freeways in Korea. Second, the research determined 23 study sites finding the capacity values of work zone after matching two kinds of data. All study sites had varying characteristics regarding traffic flow being adjacent to work zone during road works. The capacity values were reviewed in terms of lane closure configuration, the types of work, and design speed. Finally, research proposed capacity values for a short-term freeway work zone with the design speeds of 100 kph, 120 kph and 1,700 pcphpl, 1,750 pcphpl, respectively.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.145-151
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• 2009

Current highway design standards is based on the safety under the free flow condition. The length of deceleration lane is also determined in terms of the deceleration distance which is necessary for the driers to adjust the vehicle speed from the speed limit on the main road to that on the exit ramp of the interchange. However, the queues are frequently developed on the deceleration, and the following vehicles to exit must decelerate on the main road. It may cause delay on the main road and traffic accidents. This study is to suggest a methodology to minimize such problems with the shock-wave theory. The queue length of exiting vehicles can be estimated by the design speeds, traffic volumes of main road and the exiting ramp, and the countermeasures to the operational problems. According to the results, the queue length can be shortened to 80% by upgrading the design speed of exit ramp as the amount of 10km/h. Fifty percent of queue length can be shortened by adding an additional lane on the ramp to two lanes.

• 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.13 no.3
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• pp.99-120
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• 1995

가속차선이 교통류의 운영상태와 안전에 기여하는 바는 벌써부터 인식되어 왔으나 이 변속차선이 유입형 연결로 접속부 전체의 운영에 미치는 영향을 수치화하거나 체계적으로 평가하기 위해 현장 자료를 바탕으로 한 실험적 연구는 진행되어 오지 못하엿다. 현재 널리 참고되고 있는 1985년 USHCM의 접속부 운영상태 분석 방법론은 단지 차선 1의 교통량을 예측하는 데 주안점을 두고 있는데 가속 차선의 길고 짧음에 따라 접속부 바로 전 차선 1의 교통량 분포가 크게 변화한다는 사실(많은 현장 관측을 통해 확인)은 고려하지 못하고 있다. 이는 접속부 운영 상태가 같은 교통량 조건하에서도 크게 차이가 나나다는 것을 뜻하며 가속차선의 존재를 무시한채 운영과 관련한 MOE를 도출하는 것이 서비스수준 산정 방법으로 충분한 것인가 하는 의문을 자연히 낳게 한다. 본 논문은 가속차선이 고속도로 연결로 접속부의 운영에 미치는 영향을 주로 다루고 있다. 가속차선의 독립적인 역할과 영향을 체계적으로 관찰하기 위해 미국내 여러 지역에서 8개의 고속도로 연결로접속부를 선택하고 각 지점에 접속부의 상하류 지역을 포함하는 2,000ft 구간내에 다섯대의 카메라를 설치, 지점별로 약 3시간 동안 자료를 수집하였다. 총 193개 자료수의 분석을 통해서 다중 회귀 모형을 구성하는 독립변수로 가속차선의 길이를 사용하는 것이 타당하다고 결론지었으며, 접속부 운영의 질, 특히 속도를 추정하기 위한 모형을 수립하였다. 본 연구를 통해 얻어진 관점과 방법론은 1994USHCM 고속도로 연결로 분석 방법론 설정에 일부분 반영되고 잇으며 특히 교통운영과 흐름의 방식에서 유사한 엇갈림 구간의 분석 방법과 일관성 있는 분석 체계 마련을 위해서 서비스수준 산정 절차 정립에 엇갈림 알고리즘을 활용하는 방안을 제시하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.324-328
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• 2015

본 연구에서는 수심적분 2차원 수치모형인 Nays2D를 이용하여 수공구조물(낙차공)이 사주의 거동과 하천의 평면변화에 미치는 영향을 분석하였다. 길이 20m, 저수로 폭이 0.48m, 좌우안 홍수터 폭이 0.26m인 복단면 하도에서 낙차공에 의한 사주의 변화를 파악하기 위한 실험결과와 수치모의 결과를 비교하여 그 적용성을 검증하였다. 최심 하상고의 변화와 교호사주의 발생을 모의하였으며, 실험결과와 잘 일치하였다. 하폭이 상대적으로 넓고 수심이 얕은 복렬사주가 발생하는 조건에서 사주의 거동을 파악하기 위한 수치실험을 수행하였으며, 상류에서 발생한 사주의 형상이 낙차공 하류의 하도변화에 영향을 미치는 것을 파악하였다. 낙차공 상류와 하류에서 교호사주가 발달하였으며, 낙차공 상류에서 발달한 사주의 형상을 반영하여 낙차공 하류에서 교호사주가 형성되었다. 사주의 파장은 낙차공 상류의 파장보다 낙차공하류에서 짧고, 사주의 파고는 낙차공 하류에서 파고보다 상대적으로 높다. 또한 사주의 이동속도는 낙차공 상류보다 하류에서 빠른 특성을 보여주고 있으며, 낙차공에 의하여 흐름이 강하게 교란되면서 하류에서 사주가 형성되는 영향을 주기 때문으로 판단된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.3
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• pp.349-360
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• 2024

The purpose of this study is to analyze the performance of the road network according to the penetration rate of autonomous vehicles (AV) of Level 4 or higher and the change in traffic volume. First, prior studies related to vehicle control variables of AV were reviewed, and future traffic demand in 2040, which is predicted to have a 50 % market share of AVs, was reflected in the simulation analysis. In addition, the change in traffic flow of continuous and intermittent flows was analyzed by increasing the AV market penetration rate and traffic volume of passenger cars, trucks, and buses by 25 % step by step from 0 to 100 %. As a result of the analysis, it was confirmed that the travel time increased as the traffic increased, and the pattern of decreasing the travel time due to the increase in the share of AVs, that is, the development of technology, can also be confirmed. Furthermore, it was also confirmed that the traffic speed showed a trend of increasing as the share of AVs increased. In this study, it was confirmed that the law of diminishing marginal rate of substitution (MRS) was satisfied by calculating the MRS according to the combination of traffic volume and speed while increasing the market penetration rate of AVs. Furthermore, it was confirmed that the convexity of the indifference curve was also satisfied in both intermittent and continuous traffic flow environments.