PURPOSES : This study analyzed the lane-by-lane traffic flow characteristics in Korea by using real-world data, including congestion levels, for 2-, 3-, and 4-lane freeways. METHODS : On the basis of a literature review, lane flow and speed characteristics were analyzed using flow measurements and s...
PURPOSES : This study analyzed the lane-by-lane traffic flow characteristics in Korea by using real-world data, including congestion levels, for 2-, 3-, and 4-lane freeways. METHODS : On the basis of a literature review, lane flow and speed characteristics were analyzed using flow measurements and speed ratios. In addition, the effect of congestion levels on traffic flow were visualized using rescaled cumulative plots. RESULTS : Driver behavior varied depending on the congestion level. During free-flow conditions, the lane-use ratio of individual lanes varied largely, whereas during congestion, the ratio was nearly the same for all lanes (i.e., equilibrium). During maximum-flow and congestion conditions, the median lane was used more than the shoulder lane, whereas during all other conditions, the shoulder lane had a higher lane-use ratio. In 3- or 4-lane freeways, the lane-use ratio of the median lane always exceeded 1 and was the highest during free-flow conditions. CONCLUSIONS : The results of the present analysis can be used as an index to predict congestion before a lane is overcapacitated. Moreover, the results can be applied in variable lane guidance systems, such as car navigation systems and variable message displays, to control traffic flow.
PURPOSES : This study analyzed the lane-by-lane traffic flow characteristics in Korea by using real-world data, including congestion levels, for 2-, 3-, and 4-lane freeways. METHODS : On the basis of a literature review, lane flow and speed characteristics were analyzed using flow measurements and speed ratios. In addition, the effect of congestion levels on traffic flow were visualized using rescaled cumulative plots. RESULTS : Driver behavior varied depending on the congestion level. During free-flow conditions, the lane-use ratio of individual lanes varied largely, whereas during congestion, the ratio was nearly the same for all lanes (i.e., equilibrium). During maximum-flow and congestion conditions, the median lane was used more than the shoulder lane, whereas during all other conditions, the shoulder lane had a higher lane-use ratio. In 3- or 4-lane freeways, the lane-use ratio of the median lane always exceeded 1 and was the highest during free-flow conditions. CONCLUSIONS : The results of the present analysis can be used as an index to predict congestion before a lane is overcapacitated. Moreover, the results can be applied in variable lane guidance systems, such as car navigation systems and variable message displays, to control traffic flow.
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가설 설정
To analyze this data, a similar N-curve form A1, B2, C2 were selected. First, shape of N-curve of the median lane is similar to each freeway, but all have different maximum value. C2(4-lane freeway) is at it's maximum, and B2(3-lane freeway) A1(2-lane freeway) follows.
In this research, the concept of flow ratio measurement is used as a proportion of a single lane's volume to the whole volume, and if the measurement is over 1, that individual lane has a traffic volume higher than other lanes.
제안 방법
In addition speed ratio measurement is a similar concept, but, the difference is that if the ratio is over 1, it means that the certain lane has a higher speed usage than other lanes. Also, flow/speed accumulations measurement was used to analyze the change in flow and speed over a time period. Accumulation rate used here is in a form of a accumulating curve.
Mauch(2002) used the oscillations to analyze the characteristics of the queued traffic in a congested freeway. He also analyzed the traits of vehicle lane-changing depending on the freeway geometry. The result of the rescaled cumulative flow analysis showed that in near interchanges, the flow increased in the shoulder lane.
First, drivers change lane depending on their maximum desire speed, and secondly, drivers keep a low spacing in a passing procedure. In explaining this theory, drivers were differentiated into a rabbit and a slug, and the lanes into passing lane and a shoulder lane. A traffic flow state is divided into a free-flow and a congestion state.
The data was also filtered to remove the detector error, controller error, and communication line error. Occupancy over 100, velocity over 180km/h, flow(30 seconds) over 38, and flow and speed of 0 were excluded.
Past studies mostly used flow rate to analyze, but since two different values of flow rate exist, they used density instead to explain lane use distribution. This study analyzes the characteristics of individual lanes when it is in either non-congestion or congestion, which is part of a transition. In transition(non-congestion), the median lane use is lower as the density is low, and also increases when the density does.
대상 데이터
Amin and Banks(2005) analyzed lane usage depending on flow rate, time, and location by using data from flow measurement invented by Banks and Amin(2003). Data used here were collected from the detectors in the freeways of I-5, I-805, I-8, and R-78 in San Diego, USA. According to the data analysis, the flow ratio was over 1 in most of the points except where flow rate was below 500/h.
Occupancy over 100, velocity over 180km/h, flow(30 seconds) over 38, and flow and speed of 0 were excluded. Datas were collected from Seohaean(Iljik JC-Gumcheon IC, Songak IC-Balan IC), Yeongdong(N.Suwon IC-E, SuwonIC), Seoul Ring(Jayoo-ro IC-Kimpo IC, Kimpo IC-Kimepo TG, Kimpo TG-Noohji JC, Seowoon JC-Jungdong IC), which are congested freeways.
데이터처리
After analysis, Carter et al(1999) concluded that there is a difference in q-u curve in each lane and site. They collected data from Canada`s Queen Elizabeth Way (QEW) Freeway and used the ANOVA method to analyze. From the results of the lane speed distribution analysis, median lane's speed was the highest, followed by the center lane, and then the shoulder lane.
성능/효과
In this state, passing vehicles have less opportunity to pass or change lanes. In conclusion, the usage of a median lane increases in a non-congestion transition, and the lane usage of every lane become equilibrium as the density increases. In a transition during a congestion however, the middle lane and the center lane which had the highest lane usage, decreases as the density and the lane usage of a median lane increases.
후속연구
Therefore, in this study the authors seek to study the features of lane use based on the real-world data for 2-,3-,4-lane freeways with congestion levels and infer driver behavior to facilitate future behavioral modeling research.
참고문헌 (13)
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Duret, A, Ahn, Buisson C., 2012. Lane flow distribution on a threelane freeway: General features and the effects of traffic controls, Transportation Research Part C: Emerging Technologies, Vol. 24, pp 157-167.
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