The Government is predicting that ‘smart’ motorways, which convert the hard shoulder to a running lane, will boost capacity by a third and improve journey times up to 10% on the M1 and 15% on the M3.
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 new schemes are central to the Government's long-term economic plan and part of £24 billion of investment in the road network by 2021, which will see spending tripled to £3 billion each year on England's key highways and motorways.
The 'smart' motorways will operate either permanently or during busy periods. Overhead variable message signs inform motorists of changes in speed limits, queuing and lane closures, while staff in regional control centres use CCTV to monitor incidents and keep motorists safe.
Average speeds on the M1 and M3 are currently 45mph during rush-hour.
The national speed limit on these sections will remain at 70mph despite the Highways Agency previously consulting 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.
The Transport Secretary Patrick McLoughlin has rejected this approach as the Government's preferred option for managing the problem and has instead asked the Highways Agency to investigate alternatives as work progresses on the schemes in the next 12-18 months.
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.
In the meantime, as with all smart motorways already in operation, the Highways Agency will take the necessary legal powers to enable them to vary the speed limit from the routine 70mph at certain times.
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.
"Smart motorways are an effective and cost efficient way of increasing space on our roads, cutting jams and speeding up journey times and I am pleased to announce the start of work on these schemes."
These three schemes will be constructed as quickly as possible to reduce the impact on those who use the motorways and live near them.
Drivers should see an improvement in their journeys when the M1 schemes commence operation from autumn 2015, and when the M3 scheme opens to traffic in 2016.