The poor condition of more than 150 miles of Calderdale roads could leave drivers, bikers and cyclists facing "devastating crashes", figures suggest.
The charity Brake is joining calls by other organisations for a significant boost to maintenance funding to help people stay safe and avert potentially costly repairs.
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Department for Transport figures show that 21 per cent of Calderdale's council-run roads – around 151 miles – were likely to have considerable deterioration in 2018-19.
They include 26 per cent of unclassified roads, around 143 miles – four per cent of A roads and motorways, and seven per cent of B and C roads.
Roads that are likely to show considerable deterioration are categorised as "poor", and may need maintenance within the next 12 months.
Councils use human inspection or scanning machines to assess the state of a road’s surface, although the exact technique can vary between local authorities.
Across England, 12 per cent of council-owned roads were classed as being in poor condition in 2018-19 – around 21,900 miles.
Brake, which campaigns for road safety, says damaged roads “can contribute to potentially devastating crashes, with cyclists and motorcyclists most at risk”.
A spokesman added: “Investment in our road network is a must to help prevent the huge cost to society of a serious crash."
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The Conservative Party recently vowed to spend £25 billion on England's roads, with 14 major routes earmarked for improvements.
But David Renard, the Local Government Association’s transport spokesman, said the Government spends 43 times more per mile on maintaining national roads than council-controlled ones, which make up 97 per cent of the network.
He added: “With councils facing a £9 billion local roads repair backlog, we also need to see the Government’s investment in national roads matched by at least the same investment in local roads.”
Nicholas Lyes, head of roads policy at the RAC, said a driver today is twice as likely to suffer a breakdown as a result of a pothole than in 2006.
The company is calling for fuel duty funds to be ring-fenced, saying that 2p per litre could raise nearly £5 billion over five years to help clear a backlog of pothole repairs.
Roads minister Baroness Vere said travelling on poor road surfaces is “not only frustrating but also incredibly hazardous”.
She added: “That is why we are providing councils with more than £6.6 billion between 2015 and 2020 to help them repair damaged roads, and why we are also looking at innovative ways to help tackle this problem, such as trialling new materials and repair techniques.”