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 outperforms 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.

This paper studies a control strategy applicable to local ramp metering in the presence of random-location bottlenecks (RLBs) downstream of a metered on-ramp. With the support of the Highway Department of Victoria State, Australia, local ramp metering in the RLB case has recently been investigated, with the aim of designing appropriate and practicable control approaches. A related control strategy has been developed and tested in macroscopic simulation. This paper presents some representative testing results. This strategy has been incorporated into the HERO (heuristic ramp-metering coordination) freeway ramp signal control system and will be applied in Melbourne in the frame of a large-scale freeway upgrade project.

This paper studies a control strategy that is applicable to local ramp metering in the presence of random-location bottlenecks (RLB) downstream of any metered on-ramp. With the support of Vicroads (Highway Department of Victoria State, Australia), local ramp metering in the RLB case has recently been investigated, aiming to design appropriate and practicable ramp metering approaches. A related control strategy has been developed and tested in macroscopic simulation, and this paper presents some representative testing results. This strategy has been incorporated into the coordinated freeway ramp signal control system HERO and will be applied in Melbourne in the frame of a large-scale freeway upgrade project.

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Motorways represent seven per cent of the urban arterial road network in Melbourne yet carry 40 per cent of the urban arterial road travel in terms of vehicle kilometres travelled and this percentage is growing. The number of casualty crashes on metropolitan Melbourne motorways has increased over the decade at a faster rate than on other urban roads in metropolitan Melbourne. Police crash reports more often attribute crash cause to traffic conditions and vehicle interactions rather than infrastructure. As urban motorways are generally built to the highest standards, a new way of looking at motorway safety is needed. This led to the formulation of a hypothesis that the dynamics of the traffic flow are a significant contributor to casualty crashes on urban motorways. To test this hypothesis, in-depth analysis was undertaken on metropolitan Melbourne motorways. Crash data was linked to traffic data including vehicle occupancy (a proxy measure for density), vehicle speed and flow. Occupancy was used to categorise the ‘traffic states’ ranging from free flow to flow breakdown (congestion). Applying a Chi Square Goodness of Fit Test to the linked showed a statistically significant association between traffic state and crashes, with a higher than expected crashes in the traffic states where flow breakdown is relatively certain or has occurred. The results of this analysis can be used to improve safety on urban motorways through the development of Intelligent Transport System strategies to keep the motorway operating at conditions that minimise flow breakdown risk.