A traffic solution
Located at the entrance to one of the State’s major regional centres of Bunbury, the Eelup roundabout won the Regional Award category for excellence and exceptional engineering, becoming the State’s first signalised roundabout.
The Eelup roundabout is Western Australia’s largest, and connects four major roads including the Australind Bypass, a part of the main link to Perth and the State’s South West. The Australind Bypass carries 30,000 vehicles per day (vpd), while Sandridge Road carries 20,000 (vpd), Robertson Drive 15,000 (vpd) and Koombana Drive 13,000 (vpd).
The roundabout also carries traffic headed for the State’s popular south west tourist destinations, including Busselton and Margaret River.
Recognised as having the State’s worst crash rate with over 650 recorded crashes in the past five years, the roundabout also had capacity problems seen by the long queues that formed on the major roads during peak hours.
While there have been no fatalities, these crashes have cost the community an estimated $11 million, not including resultant delays and the cost of unreported accidents. The crash rate was the main driver for proceeding with the major upgrade.
The upgrade of this heavily used roundabout saw Main Roads’ South West Region apply sound engineering principles and practices to research, design and deliver the State’s first fully signalised roundabout.
This innovative traffic engineering solution significantly reduced crashes and congestion soon after installation.
Main Roads investigated many alternative layouts over several years to establish the best solution to address the roundabout’s safety and capacity problems. This work has led to the adoption of an ultimate layout that includes a flyover for traffic entering the Bunbury CBD along the Australind Bypass, with a large roundabout underneath as the preferred option.
This option was chosen giving consideration to traffic benefits, cost, use of the nearby Preston River bridges, impact on existing development, traffic disruption during construction and the potential for staged development.
Traffic modelling of the signalised roundabout showed that this treatment would increase vehicle capacity by about 40 per cent, reduce the long peak hour queues and provide sufficient capacity for the next 10 years (assuming normal traffic growth).
Other benefits the roundabout is providing include:
- A slip lane for traffic heading south, therefore removing vehicles from the roundabout.
- Trucks will find it easier and safer to enter the roundabout.
- The roundabout has lower average delays than conventional four-way signalised intersections during peak hours.
- Enhanced landscaping of the roundabout and surrounds have improved the appearance of this important entry into the City.
- Improved facilities for cyclists and pedestrians, including new paths and a footbridge, to enable them to move more safely through the site.
A special traffic signal phase has been designed for the very high volumes that occur when people travel back to Perth after long weekends. This phase will increase the flow of traffic from Robertson Drive to Australind Bypass. Closed Circuit TV cameras have been installed and are connected to Main Roads’ Traffic Operations Centre in Perth, where the signals are monitored and adjusted when required.