Revisiting Merge-Influence Area Empirically: Operations Inside Recurrent Freeway Bottlenecks

Abstract

The current effort aims to analyze traffic operations empirically at merge-influence areas positioned inside recurrent freeway bottlenecks. Four years of data at four bottlenecks in the Milwaukee County, Wisconsin, freeway system were used in the analysis. Bottlenecks were ranked on the basis of merge-area capacity use and were treated individually. The study evaluated how merge-area traffic mix influenced freeway breakdown characteristics such as prebreakdown flow (PBF), queue discharge flow (QDF), queue discharge speed, and congestion duration (CD). Merge-area traffic mix was evaluated with the ramp volume ratio (RVR), which was defined as the percentage of the ramp flow in the total merge-area traffic flow. For bottlenecks with heavily used merge areas, both capacities (PBF and QDF) and queue discharge speed were reduced when RVR increased in value. The value of CD appeared to be sensitive to RVR. The value of CD was found to double, triple, or almost quadruple when ramp flow composed a higher percentage of merge-area flow. Bottlenecks with lightly used merge areas sometimes showed different or even contradictory results. The study also modeled two capacity flows (PBF and QDF) stochastically at merge areas with the three-parametric Weibull distribution. From the current analysis, it appears that the maximum merge-area flow (4,600 passenger cars per hour) recommended by the Highway Capacity Manual is not a conservative design value.

Get full access to this article

View all access options for this article.

References

Highway Capacity Manual 2010. Transportation Research Board of the National Academies, Washington, D.C., 2010.

Minderhoud

M. M.

, Botma

, and Bovy

P. H. L.

. Assessment of Roadway Capacity Estimation Methods. In Transportation Research Record 1572, TRB, National Research Council, Washington, D.C., 1997, pp. 59–67.

Zhang

, and Levinson

. Some Properties of Flows at Freeway Bottlenecks. In Transportation Research Record: Journal of the Transportation Research Board, No. 1883, Transportation Research Board of the National Academies, Washington, D.C., 2004, pp. 122–131.

Shawky

, and Nakamura

. Characteristics of Breakdown Phenomenon in Merging Sections of Urban Expressways in Japan. In Transportation Research Record: Journal of the Transportation Research Board, No. 2012, Transportation Research Board of the National Academies, Washington, D.C., 2007, pp. 11–19.

Brilon

, Geistefeldt

, and Zurlinden

. Implementing the Concept of Reliability for Highway Capacity Analysis. In Transportation Research Record: Journal of the Transportation Research Board, No. 2027, Transportation Research Board of the National Academies, Washington, D.C., 2007, pp. 1–8.

Geistefeldt

Consistency of Stochastic Capacity Estimation. In Transportation Research Record: Journal of the Transportation Research Board, No. 2173, Transportation Research Board of the National Academies, Washington, D.C., 2010, pp. 89–95.

Ozguven

E. E.

, and Ozbay

. Nonparametric Bayesian Estimation of Freeway Capacity Distribution from Censored Observations. In Transportation Research Record: Journal of the Transportation Research Board, No. 2061, Transportation Research Board of the National Academies, Washington, D.C., 2008, pp. 20–29.

Albanese

, Camus

, and Longo

. Capacity and Queue Modeling for On-Ramp Freeway Junctions. In Transportation Research Record: Journal of the Transportation Research Board, No. 1852, Transportation Research Board of the National Academies, Washington, D.C., 2003, pp. 256–264.

Tian

Z. Z.

, and Wu

. Probability of Capacity Enhancement and Disruption for Freeway Ramp Controls: Analysis by Gap-Acceptance and Queuing Models. In Transportation Research Record: Journal of the Transportation Research Board, No. 2278, Transportation Research Board of the National Academies, Washington, D.C., 2012, pp. 1–12.

10.

Kondyli

, and Elefteriadou

. Modeling Driver Behavior at Freeway-Ramp Merges. In Transportation Research Record: Journal of the Transportation Research Board, No. 2249, Transportation Research Board of the National Academies, Washington, D.C., 2011, pp. 29–37.

11.

, and Yeo

. Estimation of Capacity Drop in Highway Merging Sections. In Transportation Research Record: Journal of the Transportation Research Board, No. 2286, Transportation Research Board of the National Academies, Washington, D.C., 2012, pp. 111–121.

12.

Ozbay

, Yasar

, and Kachroo

. Comprehensive Evaluation of Feedback-Based Freeway Ramp-Metering Strategy by Using Microscopic Simulation: Taking Ramp Queues into Account. In Transportation Research Record: Journal of the Transportation Research Board, No. 1867, Transportation Research Board of the National Academies, Washington, D.C., 2004, pp. 89–96.

13.

Sun

, and Horowitz

. Set of New Traffic-Responsive Ramp-Metering Algorithms and Microscopic Simulation Results. In Transportation Research Record: Journal of the Transportation Research Board, No. 1959, Transportation Research Board of the National Academies, Washington, D.C., 2006, pp. 9–18.

14.

Papageorgiou

, Hadj-Salem

, and Middelham

. ALINEA Local Ramp Metering: Summary of Field Results. In Transportation Research Record 1603, TRB, National Research Council, Washington, D.C., 1997, pp. 90–98.

15.

Dehman

Breakdown Maturity Phenomenon at Wisconsin Freeway Bottlenecks. In Transportation Research Record: Journal of the Transportation Research Board, No. 2395, Transportation Research Board of the National Academies, Washington, D.C., 2013, pp. 1–11.

16.

Cassidy

M. J.

Freeway On-Ramp Metering, Delay Savings, and Diverge Bottleneck. In Transportation Research Record: Journal of the Transportation Research Board, No. 1856, Transportation Research Board of the National Academies, Washington, D.C., 2003, pp. 1–5.