The hard shoulder will be permanently changed into an extra lane when a section of the M20 is converted to a smart motorway.

Highways England wants to add an extra lane between junction 3 for Borough Green and junction 5 for Aylesford to improve the flow of traffic in both directions.

The works will create an additional 11 miles of motorway capacity.

Costing up to £100m, the works will use technology to manage congestion by controlling speeds with mandatory variable speeds on overhead signs.

This week more details of the plans emerged, including confirmation the hard shoulder will be permanently removed, and emergency refuge areas provided instead.

But it is still not clear how long commuters will be subjected to roadworks.

A smart motorway already exists on the M25 between junction 5 for Sevenoaks and junction 7 for Gatwick Airport.

Work on the new carriageway is due to start in 2017 or early 2018 and it will be open to traffic by 2019 or 2020.

A total of 14 schemes are planned for the South East, including one to increase capacity on the M2 at junction 5, targeting commuters travelling between Maidstone and Sittingbourne. There will be consultation on those plans in 2017 with work expected to start in 2019.

Ken Simmonds, Highways England’s major projects director for the south, said the changes would bring long-term gains to commuters and the economy.

He said: “The construction work will, of course, bring some disruption in the short term but we will ensure we keep this to a minimum to keep traffic flowing.

“When the schemes are completed, road users will experience safer, more reliable and less congested journeys.”

But road campaigner Ian Taylor, from the Alliance of British Drivers, has warned against widening motorways “on the cheap”.

He has previously criticised smart motorways for their increased use of speed cameras, and taking the hard shoulder out of emergency use.

The scheme was first announced two years ago and is being financed by an £11bn government pot which is being shared nationally.