• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1273-1279
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• 1994

There are 3 cases that only permissive left-turn(PLT) vehicles use the possible lane for PLT. In these cases, left turn and through movements can not be included in the same lane group, hence saturation flow rate and left turn adjustment factor of PLT are obtained separately from through movement. In capacity analysis procedures at signalized intersection with PLT phasing, PLT capacity should be known to discriminate among 3 cases stated above. The capacity is directly used not only to get saturation flow rate and left turn adjustment factor, but as a threshold for the feasibility of PLT control. This study calculated through field data the critical gap and minimum headway of left turn which affect the PLT capacity. The capacity was obtained by using theoretical models, which consequently could be used to calculate the saturation flow rate and left turn adjustment factor.

• Journal of Korean Society of Transportation
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• v.16 no.1
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• pp.129-150
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• 1998

신호교차로에서의 효율적인 교통운영을 위해서는 비보호좌회전의 활성화가 필요하며 이를 위해서는 비보호좌회전이 허용되는 신호교차로에서의 교통운영의 정확한 분석이 가능해야한다. 본연구에서는 국내신호교차로에서의 운전자의 행태에 기초하여 USHCM의 비보호 좌회전 분석에서 요구되는 $g_f$, $g_q$, $P_L$, 의 현실적인 값을 산정하기 위한 모형이 제안되었으며 이에 기초하여 비보호좌회전 보정계수 및 용량분석 기법을 제시하였다. 본 연구의 결과는 다음과 같다. 첫째, 공용차로를 가진 비보호좌회전 신호교차로에서 주기당 좌회전교통량(LTC)이 5대까지의 범위에서 G(녹색신호시간)와 LTC를 변수로 한 $g_f$모형이 개발되었다. 둘째, $v_{olc}$와 $qr_o$를 변수로 한 $g_q$모형이 개발되었으며 제안된 모형에 의한 $g_q$값이 진주 및 광주에서의 현장관측치와 거의 일치함을 볼 수 있었다. 셋째, 1994 USHCM의 $P_L$모형이 LTC가 증가할수록 $P_L$값이 감소하는 비현실적인 모형의 구조를 가지므로 현실적인 모형의 구축을 위해 국내 현장자료에 기초하여 LTC를 변수로하여 $P_L$산정을 위한 단순화된 모형이 개발되었다. 넷째, 대향교통류를 통해 좌회전할 수 있는 유효녹색시간의 부분의 $g_u$를 산정하여 비보호좌회전 포화교통류율($S_{LT}$)에 주기 대 $g_u$의 비를 곱한 비보호좌회전 용량산정식이 제안되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.663-669
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• 2011

In this study, the optimal length of left-turn lane in permissive left-turn signal system at the signalized intersection which has a left-turn bay is estimated. It is a simulation analysis using the queueing theory that estimate the length of left-turn lane. Traffic density conform to the standards of operating a permissive left-turn system of the Practical Manual Traffic Safety Facilities. And each of a left-turn arrival rate, a left-turn service rate, left-turn average queueing time, for green time average queueing vehicle, for red time average queueing vehicle and average queueing vehicle cycle is calculated. As a result of this study, we would learn how much the space should be secured at the signalized intersection which has a left-turn bay. The methodology using the queueing theory to work out the optimal length of waiting lane in the permissive left-turn signal system was presented.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.67-77
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• 2003

The purpose of this study is to provide the criteria for implementing unprotected left turn at intersections with variation of traffic volume on a cross road approach. Using Transyt-7F model, the delays calculated from permissive and protected left turn signal system were compared by gradually increasing the left turn volume for a certain opposing through volume up to the volume limits to which permissive left turn is more effective, Average stopped delay of the intersection was used as the measure of effectiveness in this study. The major conclusions are (1) the lighter the traffic gets in a cross road, the more the allowable left turn volume increases. The allowable left turn volume when the ratio of cross traffic to the concerned approach traffic is 0.6 appears about 50% more than the volume when the ratio is 1.0. (2) Comparing to the criteria of the manual of traffic safety facility, the results when the traffic ratio is 0.6 seem to be most similar the criteria of manual and the results when the traffic ratio are 0.8 and 1.0 appears to be lower than the criteria of manual. (3) The possible amount of making a left turn that is inversely proportional to the opposing through traffic, decreases as the number of opposing through lanes increases. The products of volume need to be used as the criteria of permissive left turn with considerable cautions because of its low consistency.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.107-115
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• 2011

Since 2009 The Korean National Police Agency has been pushed "permissive left-turn" forward in order to making progress in Korean traffic operations system. Preceding researches manuals and guidelines present 6 standards(# of accidents # of lanes, pedestrian volume sight # of permissive left-turn lanes vehicle volume) as installation permissive left-turn. But in practical affairs it is most important that secure enough Gap-time between permissive left-turn vehicle and opposite through lane vehicle to make permissive left-turn vehicle move safer and more efficiently. This study suggests applying gap acceptance theory in microscopic model to permissive left-turn installation standards. Analysis methods of this study are field data survey statistical analysis and microscopic simulation analysis. This study collected field data by using AVI recording and measured permissive left-turn vehicle intersection passing time(T1) and against the opposite through lane vehicle Gap-time(T2). And statistical analysis performed about two values that measured before to predict the functionality between T1 and T2. These studies to overcome the limit of sample size carried out a microscopic simulation(VISSIM) plan and collect more samples to input statistical analysis.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.31-41
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• 2002

국내의 도로용량편람에 근거한 좌회전 신호의 선택기준은 4방향 접근로 각각의 방향별 교통량, 좌회전 전용차로의 유무, 차로수 등의 수많은 요인들을 통해 결정된다. 이 요인들은 각각의 특성에 따라 좌회전 신호의 선택기준에 미치는 영향력이 다르며 그 영향력의 크기에 따라 변수를 결정해야 한다. 그러나 국내에서 사용되고 있는 대부분의 좌회전 신호의 선택기준은 이러한 검토 없이 해당도로의 한 방향 좌회전 교통량과 이와 마주보며 진행하는 직진 교통량, 차로수만을 기준으로 결정되고 있다. 따라서 본 연구는 국내 도로용량편람의 알고리즘을 이용하여 좌회전 신호의 선택기준에 영향을 주는 주요 요인을 밝히고, 이 결과를 이용하여 임계좌회전 교통량 (비 보호좌회전 신호로 신호교차로의 운영효율을 극대화 할 수 있는 최대 좌회전 교통량)을 제시함으로서 비 보호 좌회전 준거를 설정하고자 하였다. 본 연구에 의한 결과는 다음과 같다. 첫째, 좌회전 신호의 선택기준에 영향을 주는 주요요인은 해당도로의 좌회전 교통량, 대향직진 교통량, 차로수, 교차도로의 교통량과 차로수이며, 이 요인들 중에서 해당도로의 차로수가 좌회전 신호의 선택기준에 가장 큰 영향을 미치는 것으로 분석되었다. 그러나, 비 보호좌회전은 일반적으로 2차로에서 운영되므로 보편적인 상황에서의 비 보호좌회전 신호의 선택기준은 해당도로의 좌회전 교통량. 대향직진 교통량 및 교차도로의 교통량에 좌우된다. 둘째, 대향직진 교통량이 커질수록 임계좌회전 교통량은 감소하는 것으로 분석되었다. 셋째. 교차도로의 교통량이 커질수록 임계좌회전 교통량은 감소하는 것으로 분석되었다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.6
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• pp.127-136
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• 2013

In order to improve the safety and efficiency of traffic signal operation, several core projects of advanced transportation operating systems were implemented in Changwon City. This project included 10 units such as the expansion of roundabout, the permitted left-turn signal operation and the effectiveness of the projects was assessed using before and after studies. This paper presented the quantitative and qualitative evaluation results for three projects: roundabout, permitted left-turn signal operation, and left-turn actuated signal operation. From the analysis results, average travel speed was improved by 16.8% from the installation of roundabouts and average travel time and control delay were reduced by 12.4% and 41.6% respectively, from permitted left-turn operation. It was found that average control delay was reduced about 26.7% from left-turn actuated signal operation. In addition, more than 57.7% of the surveyed people was satisfied with the operational performance of the roundabout implemented. It is expected that the operational performance of traffic signal can be greatly improved by incorporating the proper projects of advanced transportation operating systems in other cities.

• Journal of Korean Society of Transportation
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• v.21 no.2
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• pp.107-118
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• 2003

Highway Capacity Manual (HCM) provides an analytical delay estimation model to assist the evaluation of traffic at a signalized intersection. The model revised and included in the HCM published in the year 2000 reflects the results of recent studies and is utilized in various fields of transportation studies. For the implementation of the model in the case of permitted left turns, the HCM supplement provides a computational procedure to adjust the saturation flow rate of permitted left toms. The model however, is originally designed for a protected movement and thus underestimates the delay of permitted left turns due to its difference right-of-way nature. This document describes (1) a review of the theoretical background of the HCM delay estimation model, (2) problems embedded in the model for the delay estimation of permitted left turns, (3) a proposed model developed in this study to improve the delay estimation for permitted left turns and (4) a set of verification tests. In order to reflect various traffic and control conditions in the test, simulation studies were performed to by using the field data based on 120 different permitted left-turn scenarios. Comparison studies conducted between sets of delays estimated by the HCM and the proposed models against a set of the CORSIM delays and showed that the proposed model improved the estimation of the permitted left-turn delays. The explanatory variable of the relationship between the HCM delay and the simulation delay was 0.47 and the one between the delay estimated by the proposed model and the simulation delay was 0.77.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.4
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• pp.30-44
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• 2020

The application of PPLT is difficult to analyze and judge only from the effects of the delay time. In this study, the application of PPLT was proposed using not only the delay time of PLT and PPLT due to the change in traffic volume and the number of opposite straight lanes but also the traffic volume of passing a left turn and the number of conflict risks as indicators. According to the analysis, the more left-turn traffic than capacity and the less opposite-straight volume, the greater the PPLT effect. On the other hand, if the left-turn traffic is below capacity, the delay time will be reduced partially, but the overall passing left turn volume will not increase, and the conflict risk will increase. In addition, the conflict risk increases in the third lane or higher. Moreover, the difference of passing left-turn volume between PLT and PPLT showed a pattern similar to the delay time difference, and the PPLT coverage was wider than the difference in delay time and was associated more with the conflict risk numbers. Therefore, it would be reasonable to use passing left-turn traffic primarily, consider the delay time below the left-turn capacity, and consider the conflicting risk numbers simultaneously at or above the opposite straight three lanes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.3
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• pp.28-38
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• 2017

The study is to analyze the aggressive driving behavior in the protected/permissive left turn(PPLT) intersections in Gunsan City. As a result of the logistic regression model, increasing of driver's age and driving experience, non-peak time, no company, sedan and male have a tendency to behave aggressive driving to the opposite vehicles. When the vehicles try to turn the unprotected left in the PPLT intersection, the opposite vehicle drivers recognize them at the aggressive driving behavior if the distance to opposite vehicles is not enough. The relationship between driver characteristics and the distance to the opposite vehicles is analyzed under aggressive driving behavior. increasing of age and company, peak time tend to influence the short distance opposite vehicles while male and higher driving experience the middle and long distance. Sedan has the aggressive possibility to shorter distance opposite vehicles rather than others.