One in five local roads is in a poor condition as councils face a huge funding deficit to tackle potholes, according to a new report.
Some 20% of carriageways in England and Wales have less than five years of life remaining before they become unusable, researchers said.
This represents more than 40,000 miles of carriageways.
Spending on roads maintenance is "way short" of the amount needed, the annual study by the Asphalt Industry Alliance (AIA) stated.
The report found the gap between the amount local authorities in England and Wales received to keep carriageways in "reasonable order" and what they actually needed was £556 million in 2017/18.
AIA chairman Rick Green warned that the deterioration of local roads "continues to accelerate" because maintenance funding has "fallen short for so many years".
He accepted that the Government does not have a "bottomless pot of money" but called on it to "provide adequate funding for a well maintained and safe local road network".
Martin Tett, the Local Government Association's transport spokesman, said the amount of money spent on local roads is "miles behind" what is allocated to motorways and major A-roads.
He added: "Very few journeys begin and end on a motorway or trunk road yet government funding on the strategic road network is 52 times higher than for local roads".