Aimsun Microsimulation Analysis for Dynamic Traffic Management: Western Distributor Case Study
John Bennett
AECOM, Queensland
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ABSTRACT
The primary objective of this presentation is to demonstrate how Aimsun microsimulation modelling can be used to inform dynamic traffic management solutions for on-ground trials and implementation. Using a case study of the Western Distributor motorway in Sydney, the paper outlines how an Aimsun model was used to test a dynamic moveable median to manage flow on approach to Sydney Harbour Bridge during peak periods. The objective for the modelling was to identify potential configurations and timing for the median to optimise congestion management for on-ground trials. Findings from the on-ground trials showed a similar correlation between general network performance and the model estimates.
Background, Findings and Conclusion
The Western Distributor motorway in Sydney provides a key connection between Sydney’s western suburbs and the Sydney CBD and northern suburbs. During the AM peak, northbound flow along the motorway towards Sydney Harbour Bridge experiences significant congestion due to capacity constraints at the busy interchange with Cahill Expressway and tidal flow arrangements across Sydney Harbour Bridge. Queues often extend back along the motorway as far as Anzac Bridge, resulting in significant wait times for vehicles accessing the Sydney CBD.
This paper outlines how Aimsun microsimulation modelling was used to test options for a dynamic moveable median at the interchange to better balance congestion along the Western Distributor and Cahill Expressway. Following calibration of the model to base conditions, a number of options were tested that assumed different configurations at the interchange and different timings for when the moveable median was activated. A fine balance was needed to manage increase in flow from the Western Distributor and queuing impacts along the Cahill Expressway – timing of the median activation was estimated to be critical.
The modelling provided guidance before a solution was tested in an on-the-ground trial over a 4-day weekday period. The trial found that the benefits and impacts were similar to the modelling forecasts in terms of option timing, congestion management and flow improvement.
Author(s)
John Bennett | AECOM
John Bennett is a Principal Transport Planner with experience covering a broad range of technical areas; including traffic modelling, traffic impact assessment and major road/ public transport project development. He has a particular interest in mesoscopic and microsimulation modelling; with advanced capabilities in AIMSUN and PTV Vision software. John has managed assessments for a range of high-profile road and public transport planning design projects and has developed large scale meso/ micro models for complex activity centres.
In recent years John’s work has focussed on planning for improved bus priority and smart motorways solutions. He has spent much of his time in leading roles in the Easing Sydney’s Congestion Program Traffic Team
