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. We are only repairing earthquake damage, so most roads throughout the city will be partially repaired or patched rather than fully reconstructed. Full reconstruction will only apply where necessary.
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.
Generally, roads are fixed only after all the other infrastructure work is finished. Wastewater will be fixed first as it is deepest underground. Then comes storm water and fresh water pipes before repairing the road above.
Road repairs will happen when there is enough resurfacing in an area to make it economically feasible. Roads are generally given a temporary seal if there is a significant delay with the permanent reconstruction or if other services are yet to be repaired.
Our aim is to permanently rebuild roads and underground infrastructure in one area, during one visit; however this is not always possible. 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.