The National Audit Office (NAO) report, out yesterday, claims the speed at which Highways England’s Road Investment Strategy was put together has created risks to deliverability, affordability and value for money.
The £11.4bn programme already has 16 projects which could be scrapped because they do not provide value for taxpayers.
The Progress with the Road Investment Strategy report shows the road improvement scheme, which covers the period between April 2015 and March 2020, exceeded available funding for forecast capital costs by £841m.
The RIS was drawn up in the 17 months before the May General Election in 2015 and included plans which had not been tested for cost effectiveness.
Amyas Morse, head of the NAO, said: “The Department and Highways England need to agree a more realistic and affordable plan if they are to provide optimal value from the Road Investment Strategy.
“Highways England has been working to address the risks to deliverability, affordability and value for money that were present in 2015, but we are now nearly two years into the 5-year road investment period.
"Decisive action needs to be taken before the updated delivery plan is published in the summer if shortcomings in the current strategy are not to be carried over into future road investment periods.”
So far Highways England has completed six projects on or ahead of schedule and has started construction on a further 19, with 16 planned to be on or ahead of schedule.
According to Highways England these projects will be delivered 5% over budget.
Bridget Fox, sustainable transport campaigner at Campaign for Better Transport, said: "This report shows that the current emphasis on big road projects could waste a lot of public money and that some projects might not happen at all.
“Instead, we'd like to see the government focus on fixing the roads we have before spending billions on considering big new projects."
She added: "The government should also look at the major road network as part of an overall transport policy rather than go after big road schemes in isolation."
This report follows another out earlier this week from the Campaign to Protect Rural England, which claimed the government’s road investment strategy will provide little benefit to local communities.
