The National Party’s proposal to establish a ‘Pothole Repair Fund’ is a useful clarification of priorities and funding to replace pavements degraded by underinvestment, but it does not provide a silver bullet or set funding in place for long-term transport network maintenance.
Civil Contractors New Zealand Chief Executive Alan Pollard said the proposed fund would reallocate funding towards much-needed pavement replacements, but the focus should be on replacing tired pavements rather than spot-fixing potholes.
Long term underfunding meant road surfacing – which waterproofs the pavement underneath – had been pushed past its design life. This meant in many locations the surface had degraded to a state where the pavement beneath had suffered and needed renewal.
While the 2022 year’s large resurfacing campaign would go a long way toward waterproofing pavements that were still in good condition, in many places the network was beyond design life following years of funding roads with a 25-year design life as if they would last 200 years.
More work was needed to create a system that funds good safety outcomes in network construction and maintenance, he said.
“Do we need to embark on a major renewal programme for New Zealand’s road pavements? The answer is yes. But this would not be needed if the programme of road surfacing had been adequately funded, so it’s important we get the settings right.
“When you push the network past its design life, it is going to take more investment to bring it back up to scratch. We need better long-term funding structures in place for the construction and maintenance of our roads, or as a country, we will be worse off.”
Mr Pollard said the National Party’s proposed funding sits within the National Land Transport Programme, so it would be a reallocation of existing safety funding, and the proposal did not provide additional funding for the construction or maintenance of the transport network.
He said it was concerning to see more and more tasks that would ordinarily sit within the National Land Transport Programme ‘shuffled off’ into short-term funding pools. This demonstrated the shortcomings in the long-term funding system of road user charges and fuel excise duties used to fund road construction and maintenance.
Funding for the transport network was usually set in the Government Policy Statement for Land Transport, which was now four months overdue. Mr Pollard said this was just one of a suite of key policy documents that seemed to be stalling without progress, alongside a review of the road user charges system which had been in stasis since April 2022.
As severe weather events increase, designs must change accordingly. Given the significant damage to the network caused by severe weather events, construction of a more resilient network was needed as well as replacement of roads reaching the end of design life.
Quick fix options such as spot-fixing of potholes were sometimes necessary – but were not cost-effective. Much better would be a well-funded construction and maintenance programme including cleaning out culverts and drains, plus more robust, resilient design and increased design life of options selected for pavements and surfacing.
An ambitious programme of work was needed to provide the country with a transport network that connected communities effectively, provided a certain pipeline for a skilled road construction and maintenance workforce, and fostered economic development, he said.
“What we need from decision makers across the political spectrum is ambition to do better and commitment to long-term funding for the construction and maintenance of the country’s transport network.”
Note for journalists: what causes potholes?
The main cause of potholes is water getting into the ‘pavement’ layer below the upper asphalt or chipseal surface of the road. The pavement is the road’s foundation and is made of a specially blended aggregate designed to compact well and provide a stable base. Once water gets through the surface and into the pavement layer it acts as a lubricant and, with pressure from the traffic on top, the pavement deteriorates and potholes form.
Damage is also accelerated by heavy vehicles. An increase in vehicles’ maximum allowable weight and the additional pressure from a greater number of trucks carrying these heavier loads, combined with record breaking rainfall over the past year, has acted as one-two punch breaking down the defences of New Zealand’s road network.
Additionally, limited budgets affect the amount of annual resealing that provides a waterproof barrier to help prevent water penetration.
Waterproofing the road network is the best thing to avoid potholes forming in first place. It provides a waterproof surface and protect the pavement beneath. Potholes should be avoidable if there’s adequate investment in maintaining our roading network.
While focussed deep repair can provide a lasting solution in some cases, once the pavement has been destabilised it may be more sensible to replace the pavement in that section of road.
Repairing potholes properly takes skill and the right equipment. It’s important to avoid surfacing over flaws in the pavement as anything but a temporary fix, and it may be more sensible to renew a section of road that is reaching the end of its design life.