The announcement was made as Mr McLoughlin revealed new “smart” motorway schemes for the M1 and M3.
The Highways Agency previously consulted on proposals to limit speeds to 60mph between 7am and 7pm seven days a week because of the potential effect of the new schemes on local air quality.
However, the Transport Secretary announced today that he has rejected this approach as the Government’s preferred option for managing the problem and has instead asked the Highways Agency to rigorously investigate alternatives as work progresses on the schemes in the next 12-18 months.
A spokesman said: ‘If any proposals continue to include varying speed limits, they must only apply when absolutely necessary. In particular, the Agency must look for alternatives that maintain the 70mph limit wherever possible, particularly when traffic tends to be lighter, such as at weekends and outside of peak commuting hours.’
Patrick McLoughlin said: ‘Let me be absolutely clear, I want all motorways to run at 70mph. While it sometimes makes sense to use variable limits to keep people moving, blanket reductions are not acceptable.’
Instead, Mr McLoughlin announced three new “smart” motorway schemes on the M1 and M3, intended to ‘cut congestion and give Britain’s drivers smoother, quicker journeys’ by using hard shoulder running.
Construction will now start on the M1 junctions 28-31 in Derbyshire, M1 junctions 32-35a in South Yorkshire and on the M3 at junction 2-4a in Surrey.
The schemes will boost capacity by a third and improve journey times up to 10% through the M1 schemes and 15% on the M3, where average speeds are currently 45mph during rush-hour.
The Government emphasised that national speed limit on these sections will remain at 70mph although the Highways Agency will look to take the necessary legal powers to enable them to vary the speed limit from the routine 70mph at certain times.
The M1 schemes commence operation from autumn 2015, with the M3 scheme open to traffic in 2016.
