• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.2
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• pp.143-150
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• 2021

Roundabouts have been spreading out all over the world quickly with their attractions including capacity enhancement, safety increase and pollutant emission decrease. The history of Korean roundabout has already been 10 years. However, due to the accumulation of unclear right of way and insufficient data, the advantages of the roundabout are not fully utilized so far. Moreover, there are some differences in the capacity model of roundabouts compared to overseas capacity models. In addition, most research tend to concentrate in evaluation of roundabout performance using computer software. This paper, therefore, investigated overseas typical roundabout capacity models; empirical model and gap acceptance model, and then KHCM 2013 was compared to SIDRA model and USHCM 2010 model. It is expected that this paper will assist and guide practitioners in analyzing and estimating roundabout capacity more precise.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.25-32
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• 2010

This study deals with the roundabout by flare of entry and exit. The goal is to analyze the relative effectiveness of roundabout by flare of entry and exit. In pursuing the above, this study gives the particular attentions to comparing the performances using VISSIM software. The main results analyzed are as follows. First, the single and double roundabouts are analyzed to have LOS F in the case of total entering vehicles of 2,400pcph and 4,400pcph Second, the roundabouts by entry flare analyzed to have LOS F in the case of total entering vehicles of 2,800~3,200pcph and the roundabouts by entry and exit flare analyzed to have LOS F in the case of total entering vehicles of 3,200~3,600pcph. Finally, result of comparative analysis of roundabout and roundabout by flare of entry and exit, capacity of roundabout by flare of entry and exit are located between 1-lane roundabout and 2-lane roundabout. therefore it analyzed that roundabout by flare of entry and exit can be added to new type roundabout.

• Journal of Korean Society of Transportation
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• v.32 no.6
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• pp.651-661
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• 2014

Recently, many studies have been undertaken regarding the of introduction at roundabout in Korea. The studies related to roundabout capacity, however, is insufficient. Thus, the goal of this study is to develop a capacity model based on real data. The main results are as follows. First, roundabout capacity in Korea was analyzed using HCM capacity model based on critical gap and following time estimated by Probit model. Entry capacity in Korea was evaluated to be similar to that of the U.S in the case of low circulating flow($Q_c$), but higher in the case of high circulating flow($Q_c$). Second, the basic capacity models in Korea were newly developed based on real traffic data. Third, models that consider geometric structure were developed based on the basic models. Finally, all of the developed models mentioned above were analyzed to be statistically significant.

• Proceedings of the KOR-KST Conference
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• 2007.11a
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• pp.530-538
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• 2007

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.65-74
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• 2010

This study aims at developing a method for estimating passenger car equivalency (PCE) values for various vehicle types that could be considered in estimating capacity and delay at intersections without traffic signals, especially at modern small 3-leg roundabouts. Unlike signalized intersections, the PCE value has not yet been treated explicitly in traffic operations involving unsignalized intersections. Both empirical and theoretical approaches for determining the PCE values at modern small 3-leg roundabouts were evaluated. As a result, the PCEs derived in this study were highly correlated with those of field measurements.

• Proceedings of the KOR-KST Conference
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• 1999.10a
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• pp.315-320
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• 1999

교차로 좌회전 이동류에 대해 곡선반경의 확보여부는 용량 및 안전성측면에 많은 영향을 주게 된다. 죄회전 곡선반경의 결정은 설계기준차량의 회전궤적에 따라 결정되며 곡선반경의 모양은 원곡선의 형태를 유지하는 것이 바람직한 형태로 제시되고 있다. 교차로 설게시 곡선반경의 확보방안으로 정지선을 후퇴시키는 방안을 제시함으로서 좌회전 이동류에 대해 용량 및 안전성을 개선할 수 있도록 하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.209-215
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• 2011

Roundabout has circular traffic island in the intersection center and is kind of intersection where the automobile bypass circular traffic island. In Korea, the provisional Roundabouts Design Guidelines were published in 2004 by MLTM (Ministry of Land, Transport and Maritime Affairs). This guideline did not discussed domestic traffic circumstance. It just only introduced foreign instances and their guidelines. In addition, the recent National Competitiveness roundabouts as part of the green growth has been concentrated on the interest. In this paper, 90 degree of the 4-legged roundabout was compared with 72 degree, 45 degree, and 30 degree 5-legged roundabouts by micro simulation VISSIM. As a result of analysis, average travel time is decreased when the inscribed circle diameter become bigger the roundabout. 5-legged roundabout until 2,000 volume per hour evaluated to be similar effect at 90 degree of 4-legged roundabout.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.143-150
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• 2011

Roundabouts, which belong to traffic circles, are intersections which are similar to the existing rotary form. Roundabouts recently have been constructed all around the world. And interests in roundabouts are increasing in Korea. However, there are lacks of research on pedestrian volume which has a great influence on operation efficiency of roundabouts in urban area. Therefore, this study suggests efficiency analysis and pedestrian signals in roundabouts according to the pedestrian volume. First, VISSIM simulation was organized to analyse volume of one lane roundabouts in urban area. Second, average delay of intersections was calibrated by VISSIM simulation dividing signalized intersections and non-signalized intersections depending on pedestrian volume. Finally, this study showed that roundabouts are suitable when pedestrian volume was under 200person/hr and traffic circles with a pelican signal are suitable when pedestrian volume was over 200person/hr. And when pedestrian volume and traffic volume are over 600person/hr and 1,500vph respectively, fixed signalized intersections fit well.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.83-91
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• 2012

This study deals with the operational efficiency of roundabout. The roundabouts generally have such the merits as high capacity, delay reduction, safety improvement, and others. Circular intersection can be divided into the rotary and roundabout according to travelling priority. The objective of this study is to comparatively analyze the operational efficiency of rotary and roundabout by scenario. In pursuing the above, this study gives the particular attentions to developing 256 scenarios according to the directional and entering traffic volume and analyzing the delay using VISSIM. The main results are as follows. First, the average delay of rotary was analyzed to be 1.56-8.74 times of roundabout. Second, the operational efficiencies of rotary and roundabout were analyzed to be better in the case of bigger differences in the traffic volumes between the main and minor roads. Third, the average delay of the 4-legged was evaluated to be 1.77-11.70 times of 3-legged intersection. Finally, 2-lane intersection (3-legged & 4-legged) was analyzed to be 2.02-2.23 times of 1-lane intersection.