Once the earthworks are complete and the subgrade (layer below the pavement) has dried out sufficiently, we can start placing and cement stabilising the sub-base – first layer of the pavement made up with aggregate (65mm diameter stone). After we’ve stabilised the subbase and it’s gained sufficient strength, we start laying the asphalt. The first two layers provide the strength and durability with the final layer of EMOGPA (Epoxy Modified Open-Graded Porous Asphalt) providing a quieter running surface. While we can continue with the construction of the first two layers of asphalt through winter, except on wet days, the EMOGPA needs warmer weather and as it’s the final icing on the cake, we want to leave it until right at the end so we’re minimising the amount of construction traffic travelling over it.
The combination of asphalt layers is referred to as Deep Lift Asphalt and while it is more expensive than traditional granular pavements, it has a longer life, performs far better under heavy traffic conditions and requires less maintenance. It also provides a smoother surface than chip-seal with a subsequent reduction in tyre noise.
As always, we are aware of the disruption that large construction projects can cause and try and be mindful of how our work may affect the public. We’re also conscious of the impact that the heavy rain that we’ve been experiencing has on our temporary roads. Our team have been responding quickly to any potholes that appear and we really appreciate your patience as we address these as quickly as possible. It’s also worth noting that sometimes we carry out a temporary repair with a more permanent repair completed as soon as we get a dry period.
Stay safe, until next time.
If you need any further information, please visit our website www.nzta.govt.nz/pp2o, call us on 0800 PP2O INFO or email firstname.lastname@example.org
Chris Hunt, Project Director