Is management of Australian motorway traffic getting smarter?
Over the past five years references to traffic congestion by political and non-transport commentators in Australia has been increasing. The recently released Henry Review of Taxation included the need to ‘increase the efficiency of use and investment in roads by a program of road reforms that includes greater use of road user charges, including congestion charges’. The national government has deferred consideration of this recommendation.
Traffic congestion is primarily due to either bottlenecks in the system or unexpected incidents. The bottlenecks occur when available capacity is inadequate for the traffic demand especially during peak flows, for example because of traffic merging or weaving at junctions. Incidents include vehicle crashes, breakdowns and load spills that reduce capacity.
There have been a number of recent initiatives in Europe and North America aiming to squeeze more flow through the existing traffic network, termed ‘sweating the corridor’ by the UK Highways Agency who were the first to introduce the concept. This involves a much greater focus on reducing bottlenecks, such as by hard shoulder running during peak flows, ramp metering, variable speed limits, dynamic lane control, detecting and clearing incidents quickly and improved real-time traffic information.
The Melbourne M1 dynamic traffic management system upgrade project involves a 75 km section of the Monash Freeway – CityLink – West Gate Freeway one of the busiest transport corridors. A total of 1,100 devices are being installed over 75km cost of A$102 million, making this the biggest ITS system in Australia to date and started coming online in December 2009.
The system uses the latest intelligent transport system technologies to provide more reliable journey times, improved safety, quicker response to incidents, and improved information for drivers.
Smart traffic aspects include coordinated ramp metering, lane control and variable speed limit signs, additional incident response services, electronic message signs (including real-time traffic information), underpinned by monitoring through wireless detectors and CCTV cameras and control through sophisticated traffic management algorithms.
Over 60 sets of ramp signals are being installed along the M1 freeway, designed to operate as a coordinated control system to prevent stop-start traffic on the freeway. These signals manage congestion by balancing traffic demands feeding into the freeway, reducing the likelihood of bottlenecks forming and ensuring traffic flows more smoothly. Wireless in-road detectors are located along the freeway and on the ramps to automatically detect changes in the traffic flow.
A trial of the proposed coordinated ramp signals undertaken over 15km by Vicroads conducted in 2008 resulted in 4.9% increase in average flow (pcu/h/lane), 34.9% increase in travel speed (from 48.9 to 66 km/hr) and 65.3% reduction in delay (min/km).
At a few key locations priority lanes are also being added to give buses, trucks and high-occupancy vehicles quicker access onto the freeway. This is the first example of freight priority access to a freeway being provided in Australia.
The lane control and electronic message signs are key tools for managing incidents, providing road users to adverse traffic conditions ahead. The overhead signs can be used to close lanes to provide rapid access for emergency services and speed signs changed to reduce speed limits. The coordinated ramp metering can also manage traffic around an incident site.
Brisbane’s Managed Motorways
Queensland Department of Transport and Main Roads is planning to progressively implement managed motorways across all state controlled motorways in south east Queensland. An initial investment of A$204.8 million has being allocated for smart traffic systems to ease congestion and improve traffic flow, by installing systems to coordinate signals at on-ramps, vary speed limits, control lanes and monitor traffic.
A range of facilities are being planned including coordinated ramp signalling algorithms, lane use management, variable speed limits, dynamic message signs, improved incident detection, CCTV monitoring, fixed speed enforcement cameras, priority access for high occupancy vehicles and freight interchange controls and queue management.
The new Gateway Motorway Upgrade project includes components of the future managed infrastructure, with variable speed limit signs, CCTV cameras and detection systems being progressively installed.
Queensland is joining with other states making a funding submission to the national Infrastructure Australia for a series of managed motorway projects across Australia.
The deployment of smarter motorways has begun across Australia, starting in earnest in 2007 with the Melbourne project and now being advance din Brisbane with the managed motorway project. Still early days, with much planning and research required tuning systems to the different characteristics across the various traffic networks.