Major roads projects could be cancelled because David Cameron rushed out a £11.4 billion roads strategy months before the 2015 general election.

Mr Cameron, the then prime minister, unveiled the Government’s five-year Road Investment Strategy in November 2014, proclaiming it as the “biggest, boldest and most far-reaching road improvement programme” for 40 years.

However, Highways England and the Department for Transport are now exploring whether to cancel, delay or redesign some of the 112 schemes unveiled in the strategy.

The National Audit Office said 19 projects – nearly one in five – could be delayed to after 2020. The scheme is already £841 million over budget.

The schemes at risk of being delayed have not been identified but the overall plan includes a tunnel at Stonehenge, upgrading the M1 to a smart motorway around Sheffield and Rotherham, and improving electronic signage on the M11 between Stansted Airport and Cambridge.

It said the strategy would not provide optimal value for money unless "decisive action" was taken in the coming months.

Several problems were created by the roads strategy being designed in just 17 months in order to publish it before the May 2015 general election, the NAO said. The equivalent rail planning takes around 30 months.