LAUSR

Ramp metering (RM) has been widely used for controlling RM flow to prevent capacity drop at merge bottlenecks. In many situations, bottlenecks such as lane reduction, curvature section and traffic incident, bottlenecks with smaller capacity than the merging area, may locate further downstream. They require faster responding speed and more accurate action of RM. This study aims at proposing a fuzzy self-adaptive proportional–integral–derivative (FSAPID) control strategy for RM control at distance downstream bottlenecks, this FSAPID control is composed of proportional–integral–derivative control and fuzzy control. For the simulation of control effects, three downstream bottlenecks with different distances to the merge area are developed in the cell transmission model. The results show that the proposed algorithm reduces the total travel time by 41–43% in the stable demand scenes, and 38–42% in the fluctuating demand scenes. The results also suggest that the FSAPID control strategy has the merits of fast convergence, strong predictive ability and high action precision, and achieves preferable performance especially when the bottleneck is located far downstream.