BORR is Paving the Way Forward
The summer months have brought beautiful, sunny weather and the Bunbury Outer Ring Road (BORR) team are taking advantage of the dry season to pave the project closer to completion.
Published: 18 January 2024, Updated: 18 January 2024
There are approximately 1.3 million square meters of pavement that needs to be laid across the alignment of the BORR project.
To make the most of the drier months of the year, almost 80 per cent of this pavement construction is currently being completed. Pavement season began in October 2023 and will continue until May 2024.
Working hard before any wet weather can rain on our parade isn’t the only consideration. Different sections of the BORR alignment require different types of wearing courses, which is the material used for the top layer of the road.
The top section of the road is subjected to the most wear and tear from vehicle traffic and exposure to the elements, so choosing the right material for different sections of road is critical.
On BORR, most of the alignment consists of a spray-sealed wearing course. However, some key sections, such as interchanges and high-traffic points, feature asphalt layers.
What’s the difference?
Spray-sealed wearing courses—also known as chip seal or surface treatments—are applied by spraying a layer of bitumen across the road and layering chips on top of it. This durable course helps to reduce skidding and makes for safer driving thanks to its textured surface.
Asphalt wearing courses involve layering a hot asphalt-based mix directly onto the road. The material is then compacted to ensure a smoother and more solid wearing course, perfect for spots on the new ring road where cars are going to be turning and entering/exiting.
However, if you thought we had covered all the wearing courses used on BORR, you would be mistaken! Along a particular section of the road in Gelorup, we are using a unique Stone Mastic Asphalt (SMA) wearing course made from crushed basalt rock.
In addition to the skid-resisting, durable and long-lasting nature of the SMA wearing course, this material offers another unique feature—the high stone content in the SMA helps to reduce the noise of passing traffic vehicles.
The use of this asphalt on BORR marks a pioneering use of the wearing course that will be appreciated by both commuters and local residents alike.