Open AccessComparing the effects of ramp metering and variable speed limit on reducing travel time and crash risk at bottlenecks
Author(s) -
Li Zhibin,
Xu Chengcheng,
Li Dawei,
Liu Pan,
Wang Wei
Publication year - 2018
Publication title -
iet intelligent transport systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.579
H-Index - 45
eISSN - 1751-9578
pISSN - 1751-956X
DOI - 10.1049/iet-its.2017.0064
Subject(s) - bottleneck , metering mode , crash , cell transmission model , merge (version control) , speed limit , travel time , upstream (networking) , transport engineering , variable (mathematics) , computer science , engineering , traffic congestion , mathematics , operations management , mechanical engineering , mathematical analysis , programming language , computer network , information retrieval
Ramp metering (RM) and variable speed limits (VSLs) affect freeway traffic in different ways and, accordingly, result in different effects on travel time and crash risk. This study compared the effects of RM and VSL at different freeway bottleneck segments with various traffic demands. An isolated merge bottleneck segment was examined, and then extended to consider closely spaced upstream ramps and downstream diverge bottleneck. Two control strategies were tested which were the Asservissement LINéaire d'Entrée Autoroutiére (ALINEA)/Q and feedback‐based VSL. The reductions of travel time and crash risk were evaluated using the modified cell transmission models. The results showed that ALINEA/Q was more stable than the feedback VSL, but its power was limited by ramp space. A coordinated RM and VSL strategies were proposed to improve the control effects. The authors also evaluated how traffic demand features on mainline and ramps affected the control effects. The results highlighted the importance of consideration of geometrical features and traffic demands on freeways when selecting the best control strategy.