• Journal of Korean Society of Transportation
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• v.18 no.5
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• pp.43-56
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• 2000

본 연구의 목적은 우리 나라의 주요 간선도로상에서 운영되고 있는 좌회전 ·유턴 공용차로에 대한 적절한 보정계수를 산정하는 것이다. 이에 본 연구에서는 좌회전 2차로(1차로 유턴공용) 3개 지점 및 좌회전 ·유턴 공용 1타로 3개 지점에 대해서 연구를 수행하였으며, 유턴 전용차로 2개 지점에 대해서도 연구를 수행하였다. 좌회전 유턴 공용차로에서의 유턴 비율에 따른 포화교통류율의 변화를 분석하였으며, 회귀모형을 도출하였다. 본 연구의 연구 결과는 다음과 같다. 첫째, 중앙분리대로 분리된 유턴 전용차로를 대상으로 분석한 유턴 포화교통류율은 2,105(pcphgpl)로 산정되었다. 둘째, 좌회전 2차로(1차로 유턴공용)에 대하여 3개지점을 대상으로 유턴 비율에 따른 포화교통류율의 살펴보고 적절한 보정계수를 산정하였으며 각 차로별 좌회전 포화교통류율은 1차로는 2,105(Pcphgpl), 2차로는 2,023(Pcphgpl)이 산정되었다. 또한 유턴 비율과 포화교통류율에 따른 회귀모형을 산정하였다. 셋째, 좌회전 ·유턴 용 1차로에 대하여 3개지점을 대상으로 유턴 비율에 따른 포화교통류율의 변화를 살펴보고, 적절한 보정계수를 산정하였으며, 좌회전 포화교통류율은 2,143(Pcphgpl)으로 산정되었다. 또한 유턴 비율과 포화교통류율에 따른 회귀모형을 산정하였다. 넷째, 회귀모형의 산정결과 좌회전 ·유턴 공용차로에서는 유턴 비율에 따라서 포화교통류율이 감소하는 것으로 나타났다. 본 연구의 기대효과로는 유턴 비율에 따른 좌회전 유턴 공용차로의 포화교통류율 감소에 대하여 용량분석시 적용할 수 있는 보정계수를 제시함으로서 보다 정확한 신호교차로의 운영분석을 할 수 있다고 판단된다. 또한 신호시간 설계시에도 유턴 수요에 따른 적절한 설계에 도움을 줄 수 있으며 따라서 신호교차로의 운영효율을 증대시키는데 기여할 것으로 판단된다.

• 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.

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.65-77
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• 2007

A two-way left-turn lane is a continuous center left-turn lane that could be used as a deceleration and refuge area for both directions of left-turning vehicles. TWLTL's have been used effectively for access management treatment when applied to a highway that has wide-spread left turning traffic demand and a high-density of side streets. In this study, an effective analysis was carried out using a computer-based simulation tool, VISSIM, in order to evaluate performance and safety effects of TWLTLs and develop a warrant. In conclusion, the results indicated that there was a remarkable decrease of through and left-turning vehicle travel time delay on the main road and improvement of traffic safety.

• 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.

• 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.15 no.4
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• pp.54-67
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• 2016

All roundabouts are designed based on "Roundabout Design Guideline, Ministry of Land and Transportation, 2014" in Korea. The guideline also provides the traffic volume criteria to convert from signalized intersections to roundabouts. While the criteria are based on capacity of roundabouts, left-turn ratio and the number of lane on approaches are not considered to calculate the capacity of roundabouts. Therefore it is difficult to apply the traffic volume criteria in the real world. In this study, we studied the impact of left-turn ratio and the number of lane on approaches into capacity of roundabouts using micro-simulation. It was found that the capacity of roundabouts is changed according to left-turn ratio and the number of lane on approaches.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.5
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• pp.1-10
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• 2014

This research focuses on the warrants for the Two-Way Left-Turn Lanes (TWLTL). Using a microscopic traffic simulation tool, two key parameters were investigated herewith. One is a wide range of the Design Hourly Volume (DHV), reflective of recent Korean roadway volume characteristics, that is conventionally reduced from the Average Daily Traffic (ADT). The other is driveway spacing, the length of the middle-lane section where two conflicting left-turn demands often compete for space. In addition, unlike previous researches, the way and the procedure the TWLTL operation is realized in the VISSIM S/W with its add-on application such as VISVAP is clearly stated and described in detail. According to the result of simulations for 10 volume scenarios, as expected, the higher the volume level is, the more delay the left-tuner experience. The Level Of Service (LOS) for most cases was in the range of C and D based on the non-signalized intersection LOS criteria. Furthermore, the TWLTL was found operable up to the volume level of 1,116 and 1,860 vph in heavy direction (equivalent of volume level 7) for 3-lane and 5-lane facility respectively, which covers significant portion of existing two to four-lane highway volumes in Korea.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.2
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• pp.77-92
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• 2019

TPCLT is a advanced signal system that serves twice left turn phases during the same cycle. TPCLT can be a useful where the left turn traffic volume is high and the length of the left turn lane is short. This study examined the effectiveness of TPCLT in reducing delay for a signalized three-Leg intersection and proposed the application of TPCLT signal system. 108 scenarios with different traffic volumes were created. This study analyzed the control delay of the three-Leg intersection in case TPCLT is operated and non-TPCLT is operated. As a result of analysis, it was shown that TPCLT was effective in most of the scenarios. When traffic volume ratio of the left turn is 30~40%, TPCLT was more effective at reducing the control delay. The study result shows significant delay reduction for the left turning traffic and it is approximately 50 seconds. The opposing movement's average control delay increased 2 seconds. The effect of TPCLT on the length of left turn lane was analyzed. As a result, it is found that TPCLT is effective when the length of left turn lane is 30%~60% compared to that of conventional three leg intersection operations.

• Journal of Korean Society of Transportation
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• v.20 no.3
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• pp.31-39
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• 2002

The primary objective of this study is to develop a reliable method for estimating the left turn capacity at the signalized intersection. This study is performed during periods of congestion. Multi left turn lane(bay lane and exclusive lane) approaches are examined. When more than one left turn lane exists, traffic volumes are not distributed equally over each lane. The fundamental approach taken in this study is measuring headways on left turn lanes with altering the bay length from 20m to 120m. Left turn lane is divided into 3 sub-sections in this study. These are SLP section(start-up lost time Period), SFP section(saturation flow period), LSP section(lane selection period). Saturation flow rates are evaluated for each sub section periods. As a results of analysis, it has been confirmed that the left turn capacity can be estimated by left turn bay length and effective green time for left turn. The left turn bay length adjustment factor is suggested in this study.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.1
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• pp.42-54
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• 2018

This study is to establish the traffic volume-based warrants of left-turn lanes in unsignalized intersections based on a risk probability methodology. This study applied a risk probability of a potential rear-end collision between a left-turn vehicle and the immediately following through vehicle. With the shifted negative exponential model and the compound probability theorem, the risk probability can be expressed as the function of directional volumes, opposing volumes and the percentage of left-turns for a two-lane and four-land highway, respectively. The warrants of installing left-turn lanes on unsignalized intersections were developed with the risk probability. The warrants define the total approaching and opposing volumes to encourage a left-turn lane as a function of operating speed, percentage of left-turn, and number of lanes.