The Glossary of Austroads Terms defines an overlay as the addition of one or more courses of pavement material to an existing road surface, generally to increase strength/stiffness and/or improve riding quality.
The useful life of an asphalt overlay will vary considerably due to a wide range of environmental factors.
The table below shows the useful life for asphalt overlays adopted by Councils or published elsewhere. At the moment a life of about 20 years seems to be typical. Please feel free to add your Councils information.
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