• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2D
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• pp.205-216
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• 2008

Urban freeway is defined as the roadway with 4 lanes or more which requires a high design criteria for handling a large capacity of vehicles rapidly as a high-speed exclusive roadway in the city. However, most of the urban freeways suffer from severe traffic congestion due to the increased traffic exceeding their capacities regardless of the morning and afternoon rushhours or the inbound and outbound directions. The purpose in this study is to collect and investigate the real-time traffic characteristics based on the ramp junction influence areas of the urban freeway connected with the Busan port, compare and analyze the traffic characteristic relationship for each lane within the ramp junction influence areas, and finally assess and suggest the optimal capacity for each lane within the ramp junction influence areas.

• Journal of Korean Society of Transportation
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• v.34 no.1
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• pp.81-94
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• 2016

The Korean real-time traffic responsive control systems, Cycle Offset Split Model of Seoul (COSMOS), employs a single theoretical model to estimate the degree-of-saturation (DS) on approaches. However, the deployment of the system has been accomplished without practical consideration of its field performance. This paper delivers a diagnosis study performed to find the relationships yet known on the DS values against the operational conditions unproved in theory but ordinarily observed in field practice. Based on the analysis of the historical log data (476,505 cycles) obtained from the COSMOS server, it was found; (1) full coverage of lane detections should perform better than the sample coverage of detection in ordinary conditions, (2) the sample coverage of detection perform better than the other case with an exclusive bus lane, (3) detection in which a shared lane is involved provide poor estimation of DS, (4) poor DS estimation when a detection lane is adjacent to a shared lane, and (5) the DS values obtained during a day can hardly be stable all time. The findings suggest traffic engineers a progressive direction to move forward for the next real-time traffic control systems.

• Journal of Korean Society of Transportation
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• v.31 no.3
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• pp.65-73
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• 2013

Exclusive median bus lanes were installed to mitigate congestions on urban traffic networks. However, capacity analysis of signalized intersections having exclusive median bus lanes have not been provided in current capacity analysis process(analyses). This study aims to develop a method of capacity analysis for lane groups consisting of only buses at the signalized intersections having exclusive median bus lanes. Finding basic saturation flow rates for buses is critical since the operational characteristics between automobiles and buses are fairly different. A total of 8 intersections in Seoul were chosen as study sites. Saturation headways, distances between bus-stop and stopline, and grades of each approach were measured at the sites. It was found that the basic saturation headway and the basic saturation flow rate of buses were 3.27 s/veh and 1,100pc/h/ln, respectively. Adjustment factor for upstream bus-stop locations was estimated with 0.50 and 0.75 when the distances between bus-stop and stopline are 20m and 70m, respectively. This study explains that bus saturation flow rates are decreased in half if the bus stop locates within 20 meters from stop lines.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.2
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• pp.1-14
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• 2021

The exclusive bus lanes in the Yeongdong Expressway were implemented in the Singal to Yeoju section in 2017, but the capacity of both exclusive bus lanes and general-purpose lanes of the Yeongdong Expressway decreased and the travel time increased, reducing it to the Singal to Deokpyeong section. Therefore, it is necessary to increase the efficiency of exclusive bus lanes to revitalize public transportation and improve environmental problems. This study calculated the willingness to pay and the social benefits of permission for Green cars to drive on exclusive bus lanes in Yeongdong Expressway. A survey was conducted on two groups of Green car users and Expressway users, and the willingness to pay was estimated using the CVM method. As a result, the average WTP of Green car users were estimated to be 218.7(won/km·person), and that of Expressway users were estimated to be approximately 235.5(won/km·person). The direct benefits were estimated to be approximately 7.9 billion won for Green car users, and 8.5 billion won for Expressway users in 2019. Finally, the value of time saving was estimated to be approximately 8.0 billion won.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.595-603
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• 2019

To alleviate the demand on private car that is constantly increasing, Busan Metropolitan City (BMC) has established Bus Rapid Transit (BRT) to revitalize public transportation. But there are no unified lane system between BRT and general bus stations, which makes off-lane turning general bus to contribute to congestion. And as the bottleneck phenomenon at entrance/exit accelerates the congestion, there has been huge dissatisfaction among commuting drivers. Therefore, this study identifies efficient methods to operate better through measuring civilian awareness. We evaluate both satisfaction and drawbacks on BRT service with Importance-Performance Analysis (IPA). We first distinguish the groups by the awareness on BRT and their main transit usage, and then clarify the difference between the groups. And as a result, the group who is positive to BRT and uses buses often demands improvement in bus indoor comfort and curbing jaywalking. On the other hand, group who is negative to BRT and uses private cars often demands improvement in lane changing and the moving speed of private cars. We next examines the groups with MDPREF, one method of Multidimensional Scaling (MDS). And we have clarified that the evaluating criteria and the individual attributes of the groups corresponds very well.

• Journal of Korean Society of Transportation
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• v.33 no.2
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• pp.136-144
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• 2015

It has reported that a median bus-stop island on an exclusive median bus corridor has shortened a unit crossing distance, encouraged a pedestrian's illegal jay walking, and thus increased the number of accidents in the area. Therefore, this study plans to analyze the various crossing patterns of pedestrians at exclusive median bus corridors. This study analyzes 30,184 pedestrian crossing data which are collected from the median bus-stops, 'Express Bus Terminal,' and reveals that the rate of spatial jaywalking was 37.8%. This rate is 11.1 times higher than the rate of traffic signal violation. Therefore, this study suggests that more research needs to be done to provide a traffic safety facilities for protecting spatial crossing pedestrians and preventing jaywalking and traffic signal violation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.134-143
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• 2017

In the case of highway, there may be a large number of travel time groups when there are a bus exclusive lane, a rest area, a sleeping shelter, etc. in the corresponding section. In most of the conventional travel time estimation studies, one representative travel time (assuming normal distribution) group is assumed in the low sample collection state, and if it is out of the specified range, it is determined as outliers and then the travel time is estimated. However, if there is a bus exclusive lane, a rest area, or a sleeping shelter in the relevant section, such as the highway, the distribution of travel time will be in the form of a bi-modal or a multi-modal, rather than a regular distribution. Therefore, applying the existing estimation methodology may result in distorted results. To solve this problem, first, it should be reliable even in the case of insufficient number of samples. Second, we propose a methodology to select the representative time group among a number of time groups and to estimate the representative time using individual time data of the selected time group.

• Journal of Korean Society of Transportation
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• v.29 no.5
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• pp.157-167
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• 2011

Many problems, such as unexpected delay and collision with pedestrians or vehicles, occur generally at signalized intersections where bicycle users are frequently involved. These problems have hindered bicycle users from riding bicycles on urban highways. The aim of this study is to suggest proper traffic signal operation methods for safe and convenient highway crossing of bicycles. Three types of crossing methods at signalized intersections are proposed and analyzed: (1) indirect left turn, (2) direct left turn on an exclusive bicycle lane, and (3) direct left turn on a bicycle box. The VISSIM simulation tests were conducted based on fifty-four operation scenarios prepared by varying vehicle and bicycle traffic volumes. Both delay and the number of stops are used as the measures of effectiveness in the analysis. The results from the three-legged signalized intersections suggested that (1) the indirect left turn is appropriate when vehicle demand is high while bicycle demand is not, (2) direct left turn on an exclusive bicycle lane is appropriate when both vehicle and bicycle demands are high, and (3) direct left turn on a bicycle box is appropriate when both vehicle and bicycle demands are light.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.205-215
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• 2008

As static traffic assignment has reached its limitation with ITS policy applications and due to the increase of interest in studies of ITS policies since the late 1980's, dynamic traffic assignment has been considered a tool to overcome such limitations. This study used the Dynameq program, which simulates route choice behavior by macroscopic modeling and dynamic network loading and traffic flow by microscopic modeling in consideration of the feasibility of the analysis of practical traffic policy. The essence of this study is to evaluate the feasibility for analysis in practical transportation policy of using the dynamic traffic assignment technique. The study involves the verification of the values estimated from the dynamic traffic assignment with South Korea's expressway network and dynamic O/D data by comparing results with observed link traffic volumes. This study used dynamic O/D data between each toll booth, which can be accurately obtained from the highway Toll Collection System. Then, as an example of its application, exclusive bus-lane policies were analyzed with the dynamic traffic assignment model while considering hourly variations.

• Journal of Korean Society of Transportation
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• v.34 no.4
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• pp.291-303
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• 2016

The number of traffic accidents at intersections has been increased over the past decade, and in 2014, accounted for 44% of the total traffic accidents. In addition, since most of road accident black spots include signalized intersections, the improvement of safety on signalized intersection is top priority for national road safety program in Korea. For the decision of most effective action plan for the safety of signalized intersection, this study conducted meta-analyses to assess the effects of various road safety facilities at signalized intersection on traffic accidents. We selected 19 articles regarding the prediction of traffic accidents at signalized intersection and calculated 34 individual effect sizes on 8 variables included in the articles. The results found that there was a statistically significant negative relationship between the occurrence of traffic accident and the presence of all of road safety facilities except an exclusive left turn bay. It shows that most of the road safety facilities could prevent traffic accidents, and intersection channelization has the most effective on the reduction of traffic accidents followed by left-turn acceleration lane, lightning, crosswalk, exclusive right-turn lane and median barrier.