Heuristic Ramp-Metering Coordination Strategy Implemented at Monash Freeway, Australia
A new traffic-responsive feedback control strategy, heuristic ramp-metering coordination (HERO) that coordinates local ramp-metering actions in freeway networks is presented. The proposed coordination scheme is simple and reactive [i.e., based on readily available real-time measurements without the need for real-time model calculations or external disturbance (e.g., demand) prediction]. HERO employs an extended version of the feedback regulator ALINEA at the local level. The new strategy overcomes the problem of uncertain freeway capacity by targeting the critical occupancy for maximum throughput. HERO out-performs uncoordinated local ramp metering and approaches the efficiency of sophisticated optimal control schemes. HERO has been implemented by VicRoads, the road authority for the state of Victoria, Australia, at six consecutive inbound on-ramps on the Monash Freeway in Melbourne, Australia. This pilot project is part of the Monash-CityLink-West Gate (MCW) upgrade. The obtained results show a significant increase of traffic throughput and a reduction of travel times compared with the previously used ramp-metering system. To maximize performance across the entire 75-km route of the MCW upgrade, HERO is currently under implementation at 63 on-ramps.