Rebuilding the road network
The rebuilding work we're doing is quite varied. In general it's rebuilding on what we call a “like for like” basis, so we replace damaged roads with the same type of road, although where practicable we improve the road's ability to withstand future earthquakes.
Whenever we work on or near roadways we have a number of techniques to manage the traffic, so that we minimise disruption and keep it as safe as possible.
Because infrastructure like pipes and cables are sometimes located under the road, we may only temporarily seal the road to a safe standard. Apart from exceptional circumstances, our plan is to rebuild the road to its permanent high standard only after all the work under it has been finalised. That is, when the other infrastructure networks have been rebuilt.
Our aim is to permanently rebuild roads and underground infrastructure in one area, during one visit. This will take time. Work is being prioritised and will be carried out over the five years of the rebuild.
Road users should take extra precautions because of the damage and the current temporary nature of many road repairs:
- be aware that cyclists may not be able to keep as far left as normal
- observe speed limits and temporary speed limits
- look ahead for obstacles on the road
- allow extra time for the possibility of detours or heavy traffic.
We have reduced speed limits temporarily on some roads to prevent further damage. In some cases, there is a reduced limit to lessen shaking in nearby houses.
How we rebuild roads
Simple repairs to the road firstly involve removing the seal or asphalt by excavating (digging) the road surface. Larger repairs require milling, stabilising, or further excavation so we can strengthen the area under the road before the surface is laid.
For the larger repairs, we then lay the aggregate (gravel) road base, shape it with a grader, and compact it with a roller. Sometimes we apply water to ensure that aggregate layers are well compacted.
Usually we replace the same surface that existed before (“like for like”). We either lay asphalt or seal the road with bitumen and gravel chips.
We also check the kerbs and channels. Sometimes we can patch them, but in other cases we need to lay new sections. A special kerb laying machine produces a moulded concrete kerb and channel section.
The road is ready to use again when markings, signs, and road furniturehave been reinstated.
We sometimes use innovative techniques to ensure the rebuilt infrastructure is better able to withstand future earthquakes. While rebuilding the northbound lane of Fitzgerald Avenue, we are stabilising the supporting surface with stone columns deep underground.
Did you know?
Surfaced roads are not flat. Sealed roads are usually designed on a slight angle sloping towards the kerb. This helps prevent a safety hazard from water pooling on the road surface.