The Government is understood to be delaying the publication of the £25bn next phase of its roads programme.

The next five-year Road Investment Strategy, known as RIS2, is due to come into action on 1 April and was expected to be published alongside the Budget statement tomorrow.

But now the Government is reported by the Times to be delaying the roll-out over climate change concerns following the Court of Appeal ruling that Heathrow expansion was unlawful because the Government had failed to take account of the UK’s climate change commitments.

The delay also comes as many civil engineering contractors complain that the RIS1 roads projects have still not started.

Also, the centrepiece Smart motorways programme is at a crossroads awaiting the outcome of a Government safety review as a result of a sharp rise in near misses.

It is looking at the frequency of emergency refuge areas which were placed 500m apart on the first M42 pilot scheme, but can be 2.5km  apart on stretches of the M25.

Existing projects have also worried Highways England chiefs because they have suffered significant cost overruns.

It is rumoured that the publication of the RIS2 plan has been pushed back until later in the spring or even early summer.