• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.145-152
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• 2002

Real-time queueing information and/or predictive queue built-up information can be a good criterion in selecting travel options, such as routes, both for users, and for operators in operating transportation system. Provided properly, it will be a key information for reducing traffic congestion. Also, it helps drivers be able to select optimal roues and operators be able to manage the system effectively as a whole. To produce the predictive queue information, this paper proposes a predictive model for estimating and predicting queue lengths, mainly based on Kalman Filter. It has a structure of having state space model for predicting queue length which is set as observational variable. It has been applied for the Namsan first tunnel and the application results indicate that the model is quite reasonable in its efficacy and can be applicable for various ATIS system architecture. Some limitations and future research agenda have also been discussed.

• Journal of Korean Society of Transportation
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• v.19 no.4
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• pp.109-121
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• 2001

본 연구는 공간적 정보를 수집할 수 있는 영상검지기를 이용하여 주어진 대기행렬길이를 기반으로 하는 최적주기 알고리즘을 개발함으로써 교통신호 제어에 대한 새로운 신호계획을 제공한다. 본 연구에서는 교통수요의 공간적인 정보를 획득하는 방안으로서 영상검지기 기반의 대기행렬길이를 사용한다. 전략적 측면에서 다양한 교통상태를 적용하였으며, 주요 결과는 아래와 같다. 1. 영상검지기 기반의 대기행렬길이 계산방안을 제안한다. 이 방법은 한 링크의 상류부와 하류부에 2대의 영상검지기를 설치하여 대기행렬길이를 산출하는 방안이다. 2. 신호제어 변수인 주기 계산모형이 개발된다. 이 방법 역시 영상검지기를 기반으로 하는 대기행렬길이를 사용한다.

• Proceedings of the KOR-KST Conference
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• 1998.10b
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• pp.297-297
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• 1998

고속도로의 교통혼잡을 관리하기 위해서는 근본적으로 혼잡지점 상류부의 진입교통량을 제어해야 한다. 이를 위한 효과적인 램프미터링 운영전략이나 고속도로 교통정보제공방안을 수립하기 위해서는 혼잡영향권(대기행렬길이)에 관한 신뢰성 있는 데이터가 반드시 필요하다. 고속도로의 대기행렬길이를 산정하기 위해 일반적으로 충격파이론과 Queueing이론을 제시하고 있다. 그러나, 기존의 충격파 이론을 포물선형의 교통량-밀도관계식을 근거로 하고 있어 충격파간에 발생하는 부수적인 충격파를 해석하는 과정이 수학적으로 불가능하여 실질적인 목적으로 사용할 수 없음은 이미 잘 알고 있는 사실이다. 최근에 이러한 한계를 극복할 수 있는 새로운 방법으로 교통량 밀도간의 관계식을 삼각형으로 가정하고 교통량 대신에 누적교통량을 사용하는 Simplified Theory of Kinematic Waves In Highway Traffic이 개발(Newell, 1993)되었지만, 이 방법을 적용하기 위해서는 기본적으로 대상 고속도로 구간의 교통량-밀도관계식을 규명해야 하는 어려움이 있다.(사실 실시간으로 밀도데이터를 수집하기란 불가능하다.) Queueing이론에서 제시하는 대기행렬은 모두 대기차량이 병목지점에 수직으로 정렬하여 도로를 점유하지 않는 Point Queue(혹은 Vertical stack Queue)로서 실제로 도로상에 정렬된 대기행렬(Real Physical Queue)과는 전혀 다르다. 이미 입증된 바 있어, Queueing이론을 이용함은 타당성이 없다. 이러한 사실에 근거하여 본 연구는 고속도로 대기행렬길이를 산정할 수 있는 모형개발을 위한 기초연구로서 혼잡상태의 연속류 특성을 분석하는데 목적이 있다. 이를 위해, 본 연구에서는 서울시 도시고속도로에서 수집한 실제 데이터를 이용하여 진입램프지점의 혼잡상태에서 대기행렬의 증가 또는 감소하는 과정을 분석하였다. 주요 분석결과는 다음과 같다. 1. 혼잡초기의 대기행렬은 다른 혼잡시기에 비해 상대적으로 급속한 속도로 증가함. 2. 혼잡초기의 대기행렬의 밀도는 다른 혼잡시기에 비해 비교적 낮음. 3. 위의 두 결과는 서로 관계가 있으며, 혼잡시 운전자의 행태(차두간격)과 혼잡기간중에도 변화함을 의미함. 4. 교통변수 중에서 대기행렬길이를 산정하는데 적합한 교통변수를 교통량과 밀도로 판단됨. 5. Queueing이론에서 제시하는 대리행렬길이 산정방법인 대기차량대수$\times$평균차두간격은 대기행렬내 밀도가 일정하지 않아 부적합함을 재확인함. 6. 혼잡초기를 제외한 혼잡기간 중 대기행렬길이는 밀도데이터 없이도 혼잡 상류부의 도착교통량과 병목지점 본선통과교통량만을 이용하여 추정이 가능함. 7. 이상에 연구한 결과를 토대로, 고속도로 대기행렬길이를 산정할 수 있는 기초적인 도형을 제시함.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.4
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• pp.239-246
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• 2009

In this study, we analyze the mean waiting time on the nested open queueing network, where the population within each subnetwork is controlled by a semaphore queue. The queueing network can be transformed into a simpler queueing network in terms of customers waiting time. A major characteristic of this model is that the lower layer flow is halted by the state of higher layer. Since this type of queueing network does not have exact solutions for performance measure, the lower bound and upper bound on the mean waiting time are checked by comparing them with the mean waiting time in the transformed nested queueing network. Simulation estimates are obtained assuming Poisson arrivals and other phase-type arrival process, i.e., Erlang and hyper-exponential distributions. The bounds obtained can be applied to get more close approximation using the suitable approach.

• Journal of Korean Society of Transportation
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• v.23 no.8 s.86
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• pp.181-191
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• 2005

This study developed an algorithm for real-time signal control based on the detection system that can collect sectional travel time. The signal control variable is maximum queue length per cycle and this variable has a sectional meaning. When a individual vehicle pass through the detector, we can gather the vehicle ID and the detected time. Therefor we can compute the travel time of an individual vehicle between consecutive detectors. This travel time informations were bisected including the delay and not. We can compute queue withdrawing time using this bisection and the max queue length is computed using the deterministic delay model. The objective function of the real-time signal control aims equalization of queue length for all direction. The distribution of the cycle is made by queue length ratios.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.1
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• pp.1-14
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• 2014

The expansion of the physical road in response to changes in social conditions and policy of the country has reached the limit. In order to alleviate congestion on the existing road to reconsider the effectiveness of this method should be asking. Currently, how to collect traffic information for management of the intersection is limited to point detection systems. Intelligent Transport Systems (ITS) was the traffic information collection system of point detection method such as through video and loop detector in the past. However, intelligent transportation systems of the next generation(C-ITS) has evolved rapidly in real time interval detection system of collecting various systems between the pedestrian, road, and car. Therefore, this study is designed to evaluate the development of an algorithm for queue length based real-time traffic signal control methodology. Four coordinates estimate on time-space diagram using the travel time each individual vehicle collected via the interval detector. Using the coordinate value estimated during the cycle for estimating the velocity of the shock wave the queue is created. Using the queue length is estimated, and determine the signal timing the total queue length is minimized at intersection. Therefore, in this study, it was confirmed that the calculation of the signal timing of the intersection queue is minimized.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.179-191
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• 1999

To device effective freeway traffic flow control strategies and freeway traffic information dissemination strategies, it is very important to estimate real physical queue length on the freeway. Shock wave theory and queueing theory have limitation to be used to estimate the queue length. The primary objective of this study is to develop a reliable method for estimating the physical queue length and level of congestion. Queueing propagation processes were analysed by using such traffic data as main line traffic volume, ramp volume, density. speed, and physical queue length collected by video photographing on Olympic Freeway. As a result of analysis, it has been confirmed that the real queue length can be estimated by using the traffic counts arriving the congested region and passing a bottleneck location. Further more, a reliable method for estimating the level of congestion could be developed on the basis of real-time traffic counts.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.85-94
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• 2004

Loop detection systems have been used in real-time signal control system to collect traffic information for estimating queue lengths. The queue length algorithm uses speed as a key variable estimated from occupancy time and average vehicle length. The measurement of average vehicle length is affected from the lengths of feeder cable, but their effects have not yet been evaluated. In this study, the variability of average vehicle length due to the lengths of feeder cable is assessed through a field study, and a practical guidelines is proposed. By applying this result, the operational performance of real-time signal control system could be improved.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.660-661
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• 2017

We consider a discrete-time queue with batch geometric arrivals, geometric services, and retention of reneging customers, in which retention probability depends on the number of customers in the system. The steady state distribution of the number of customers in the system is derived.

• Journal of Korean Society of Transportation
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• v.21 no.2
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• pp.63-70
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• 2003

Real-time information on vehicle queue at intersections is essential for optimal traffic signal control, which is substantial part of Intelligent Transport Systems (ITS). Computer vision is also potentially an important element in the foundation of integrated traffic surveillance and control systems. The objective of this research is to propose a method for detecting an exact queue lengths at signalized intersections using image processing techniques and a neural network model Fuzzy ARTMAP, which is a supervised and self-organizing system and claimed to be more powerful than many expert systems, genetic algorithms. and other neural network models like Backpropagation, is used for recognizing different patterns that come from complicated real scenes of a car park. The experiments have been done with the traffic scene images at intersections and the results show that the method proposed in the paper could be efficient for the noise, shadow, partial occlusion and perspective problems which are inevitable in the real world images.