Maintenance road resurfacing
We follow an industry-wide approach to choose the most effective way to surface roads. We use a process flowchart that helps us consider factors like how many vehicles use the road, its current condition and the existing surface. This often results in several choices and helps us to find the best option. We base our final decision on a balance of safety, long-term costs, and the budget we have available.
To spend ratepayers' money wisely, we first look for the cheapest solution that still works well. We also check the road’s strength, shape, texture, and how waterproof it is. For roads with fewer than 15,000 cars a day and under 400 heavy vehicles, we usually recommend chipseal.
Before resurfacing, we carry out 'pre-seal' repairs on streets to fix small issues and improve drainage. We often complete these repairs up to a year before the resurfacing to ensure the road is safe and provides good value for the community in the meantime.
Types of road resurfacing
- Chipseal involves spraying a dark liquid (known as a binder) on the road and spreading chip to create a strong surface. Larger chip is used for commercial and heavy vehicle routes, while smaller chip suits residential areas as it minimises noise.
We typically use chipseal surfaces because they are safer for road users, are easy to construct and are cheaper. The texture of a chipseal surface provides greater skid resistance, improves surface grip and reduces the length of time it takes to stop when braking in an emergency. The chipseal surface also improves how waterproof the road is, which preserves the foundation and prevents the road from deforming.
- Asphalt is used when it's the most suitable option for a road or footpath, despite the higher costs involved. We consider things like the need for a smoother surface, improved user experience, or where we have lots of vehicle movement. We use thin asphalt mixes with various stone sizes as a good way to surface pavements.
As with chipseal, we have different types of mixes available for different purposes. Some are designed to allow water to flow through (porous asphalt), while others are designed to be fully waterproof. The main difference between asphalt and chipseal is that asphalt leaves a smoother road surface, but it’s 5-6 times more expensive than a chipseal surface.
- Rejuvenation is a process where we spray binder over an existing road, but don’t apply any chip. As a road ages, the surface becomes brittle and cracks, so we use rejuvenators to liven up aged surfaces, fill in minor cracks and make it waterproof again. Think of it as collagen for roads.
We can’t use rejuvenation in all situations, but we’ve used it over the past few years in low-speed, low-risk areas where the surface texture is suitable. This is a really cost-effective way to extend the lifetime of a road surface.
- Microsurfacing is a process where we spray a slightly thicker product embedded with very small stones or sand over an existing road surface.
This becomes the new surface for traffic to drive on and can be used on both chipseal and asphalt surfaces. Not only does it waterproof the existing surface and provide good surface grip, the binders we’re using provide extra strength to lock together the surface and resist the significant pressure that’s created when heavier vehicles turn on the road.
Maintenance road strengthening
This work is more extensive, invasive and expensive than road resurfacing, as it can require digging up and replacing all of the layers of the road. This work can be complex because it requires working with all of the layers under the road. These layers include the base course, sub-base, several sub-grade layers and then the natural ground. These layers can differ a lot, depending on where we’re working.
We only add strength to a road when the costs to maintain it become too high and it’s considered more cost-effective to rebuild the whole road. We've recently added strength to roads where more structural support has been needed to accommodate the additional weight, acceleration and braking forces of electric buses.
In chipseal roads you can expect to see another chipseal surface applied about a year after the first surface is laid. This ensures the road is fully waterproof and will meet the lifetime we expect for roads. On asphalt roads, the surface is considered fully waterproof as soon as it’s applied to the road.
Maintenance footpath resurfacing
This involves the old surface being removed and may also require minor work to ensure any water that lands on the footpath falls toward the road. We then lay the new surface.
Around Christchurch you can expect to see a few different surface materials used, the majority of which will be either asphalt, or concrete. We use concrete in areas where trees continue to cause damage to the footpaths due to constant movement. In these situations, we install hinges in the footpath that allow it to move vertically with the trees, which means the footpath stays safe and easy to walk on and doesn’t cause tripping hazards.
We often renew footpaths that have a vehicle crossing running through it. Sometimes we’ll need to renew the vehicle crossing at the same time as the footpath to make sure it meets our Construction Standard Specifications (CSS). If there’s no footpath running through a vehicle crossing, they're considered to be private property and are not maintained by Council.
Maintenance kerb and channel renewal
This work involves removing and replacing the existing kerb and flat channel (gutter) to make sure water can flow to the nearest roadside drain. This doesn’t include renewing dish channel (the older style of gutter) and changing it to the newer style of flat channel, as those projects are managed by another team within the Council’s transport unit.
Most of the kerb and channel we replace is because water is not flowing well to the nearest roadside drain. This is why you may see such long lengths being replaced along the road.
2,887 Customer Service Requests (CSRs) received about footpaths.
6,637 potholes were reported on sealed roads:
649 potholes were reported on footpaths:
Our Rapid Response Footpath Crews (RRFC) completed 3,424 jobs last financial year.
