Observing freeway ramp merging phenomena in congested traffic

Abstract

This work conducts a comprehensive investigation of traffic behavior and characteristics during freeway ramp merging under congested traffic conditions. On the Tokyo Metropolitan Expressway, traffic congestion frequently occurs at merging bottleneck sections, especially during heavy traffic demand. The Tokyo Metropolitan Expressway public corporation, generally applies different empirical strategies to increase the flow rate and decrease the accident rate at the merging sections. However, these strategies do not rely either on any behavioral characteristics of the merging traffic or on the geometric design of the merging segments. There have been only a few research publications concerned with traffic behavior and characteristics in these situations. Therefore, a three-year study is undertaken to investigate traffic behavior and characteristics during the merging process under congested situations. Extensive traffic data capturing a wide range of traffic and geometric information were collected using detectors, videotaping, and surveys at eight interchanges in Tokyo Metropolitan Expressway. Maximum discharged flow rate from the head of the queue at merging sections in conjunction with traffic and geometric characteristics were analyzed. In addition, lane changing maneuver with respect to the freeway and ramp traffic behaviors were examined. It is believed that this study provides a thorough understanding of the freeway ramp merging dynamics. In addition, it forms a comprehensive database for the development and M. Sarvi, M. Kuwahara and A. Ceder 146 implementation of congestion management techniques at merging sections utilizing Intelligent Transportation System.

Variable speed limit control for steady and oscillatory queues at fixed freeway bottlenecks

“…The onset of queue accompanies two well-known phenomena. One is ''capacity drop,'' in which the bottleneck discharge rate diminishes substantially (10-30%) (Banks, 1991;Bertini and Leal, 2005;Cassidy and Bertini, 1999;Edie and Foote, 1958;Hall and Agyemang-Duah, 1991;Kerner and Rehborn, 1996;Sarvi et al, 2007). The other is stop-and-go disturbances (also known as wide moving jams) that induce oscillatory driving in queued traffic.…”

Operational Effects of Acceleration Lane on Main Traffic Flow at Discontinuities

“…Further research should be put in the validation of the developed model based on a real traffic network. It is expected that the developed model is able to capture correctly the complex traffic phenomena at freeway discontinuities observed in literatures, for example by Sarvi et al (2007).…”

Capacity drops at merges: New analytical investigations

“…Experimental findings show that capacity drops are often observed at merges even if downstream traffic conditions are in free-flow, e.g. (Cassidy and Bertini, 1999;Kerner, 2002;Chung et al, 2007;Sarvi et al, 2007;Zheng et al, 2011). The magnitude of the capacity drops is mentioned to be between 10 to 30% of the maximal observed flow.…”