Introduction
So far this financial year, we’ve received over 29,000 reports of safety defects, of which 10,144 were reports of potholes on our roads. We’ve completed
- 18,675 pothole repairs, with over 95% using the ‘sides sawn and sealed’ method
- 9,600 pothole repairs covering approximately 10,500sqm using the Velocity road patchers in more rural areas
- 23,625 sqm worth of patching across 299 jobs
- 3,000 sqm of repairs in a trial of mastic asphalt
How we repair potholes
We use three main methods to repair potholes on our roads:
- Sawn repairs, which involves cutting out the defective area of the highway to create solid edges around the pothole, breaking out the entire cut area to a solid base, sealing the area with a bituminous seal, then backfilling and compacting with the appropriate surfacing material. Sawn repairs are used in more urban, high-traffic areas.
- Unsawn repairs, which involve removing all failed material, sealing the area with a bituminous seal, then backfilling and compacting with the appropriate surfacing material. This repair type will only be used when a sawn repair is not practical and when a quick repair is needed to remove a safety issue, for example, large areas of the road have structurally failed.
- Spray injection patching, which uses high velocity air to clear out any debris from the pothole before applying a coat of cold bitumen emulsion to provide a waterproof seal, followed by a mixture of aggregate and bitumen emulsion to form the repair before compacting the area down. Spray patching is used in rural areas to tackle both potholes and other areas where the road is showing signs of weakening.
- Mastic asphalt. As part of our continued efforts to ensure the repair techniques we use are durable, consistent quality and cost effective, we have also been carrying out a 3 month trial of mastic asphalt to repair potholes in high stress areas on our roads such as junctions. Over the trial period, we’ve completed 3000sqm of durable, highly waterproof defect repairs.
We also deliver a number of other activities to manage carriageway deterioration:
- Small hand-patching resource, delivering high quality permanent sawn repairs up to 20sqm per site.
- Large hand-patching resource, delivering high quality permanent sawn repairs up to 100sqm per site.
- Large machine-patching resource, delivering high quality permanent sawn repairs up to 500sqm per site.
How potholes form
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Water seeps through cracks in the road surface, collecting in the layers of road construction. -
Over time, water continues to saturate the layers of road construction, softening and creating small voids which creates weak areas. -
When the water freezes, it creates expansion in the road construction, creating larger voids and weakness, which leads to the road surface cracking and holes appearing. -
The cycle of freezing temperatures and thawing, along with prolonged saturation, causes continued weakness and the holes in the road surface increase. Traffic adds stress to weakened areas. -
Potholes can continue to form during summer months, usually where the road has been impacted and weakened by the previous wet and cold weather. -
The stress and weight of traffic breaks up the road surface to form a pothole. Wear from traffic expands the hole.
Other maintenance
It's not just about potholes, our Highways Operations teams also manage: