For two years one of Kent's main motoring arteries has been stalled by roadworks.

Highways England is converting six miles of the M20 into a Smart Motorway between Junction 3 for West Malling and Junction 5 for Aylesford.

KMTV examine controversial Smart Motorways

This week the authority announced it was putting a hold on new Smart Motorway schemes while the Department for Transport carries out a full scale review of their safety. We look at the background to this and what we know about the county's scheme.

What is a Smart Motorway and what will the M20's look like?

The first Smart Motorway opened in 2006 on the M46. Existing motorways are widened to fit an extra lane by replacing the hard shoulder.

In some cases the lane acts as both a hard shoulder and when necessary, a live running lane.

For the M20 all four lanes will be live. Instead of a hard shoulder motorists will have to rely on five emergency refuge areas.

Sam Cockerill's partner was killed recovering a car on the side of the M25 in 2017 and feels more could be done.

She said: "There should be more refuge areas and more education out there."

New gantries are being installed to improve electronic signage so motorists will be aware of lane closures, traffic or other alerts.

Is it safe to remove hard shoulders from motorways?

Highways England has always maintained Smart Motorways are safe.

But serious concerns have been raised following five deaths across the country.

Last week Tracey Crouch promised to write to Highways England, after hearing the authority does not have the technology to detect stopped vehicles on motorways, instead relying on calls from the public or emergency services.

The Chatham and Aylesford MP told KMTV this week: "Drivers don't know what to do in an all lane situation. I think it's scary.

"Even though I'm an incredibly confident driver I know I'd be petrified if I broke down on a smart motorway, particularly with a small child in the back of the car."

Earlier this week the boss of Highways England Jim O'Sullivan admitted some Smart Motorway schemes were "too complicated" for drivers and announced it was putting a hold on new Smart Motorway schemes.

Who has died on our roads?

In March last year van driver Derek Jacobs died after stopping his van where the hard shoulder once was on the M1 in Derbyshire.

At least five people have died on Smart Motorways, four on the same stretch of the M1 where all lanes are running.

In May 2018 an eight-year-old boy died on the M6.

Dev Naran was tragically killed after a lorry hit his grandfather’s Toyota, despite the vehicle being stationary with its hazard lights on.

This prompted assistant coroner Emma Brown to say she wanted information from Highways England on how it can improve detection of stranded motorists.

What did Highways England say in response to the youngster's death?

A spokesman said: "First and foremost our deepest sympathies are with the family of Dev Naran and those affected by this tragic incident. Any death on our network is one too many and we take our responsibilities very seriously.

“The coroner stated that there was no evidence of any legitimate reason for the Toyota Yaris stopping in a live lane. We cannot urge drivers strongly enough to ensure they only stop on the motorway in an emergency and to then follow published advice, found at highwaysengland.co.uk/motorways, about what to do next."

And what has the agency been saying about Smart Motorway safety?

It says the new-style of motorways include more features than conventional ones to further enhance safety, and both are significantly safer for drivers than other roads. The evidence shows that where smart motorways have been introduced there have been fewer collisions and congestion has reduced despite an increased number of vehicles using them.

What safety features will the M20 section have?

Highways England says all lane running schemes (another name for Smart Motorways) include “pan-tilt-zoom” CCTV systems with infra-red, signals and electronic messages to keep road users up to date on lane closures, speed limits and traffic.

A spokesman said all Smart Motorways have MIDAS – motorway incident detection and automatic signalling - system to detect serious incidents.

There have been calls to introduce Stopped Vehicle Detection on the M20, but Highways England has not confirmed if the M20 will be getting this. It says just because a section of carriageway doesn't have this technology, it does not mean it is inherently unsafe.

What do motoring bodies say?

The AA had been speaking out before the government announced its review.

Edmund King, AA president said: “We believe the Secretary of State should now announce a review into the safety of All Lane Running Schemes.

“Unfortunately we have already seen fatalities where vehicles have been left in vulnerable positions in live lanes. Previous research has shown that if Stopped Vehicle Detection is not in place it takes an average of 17 minutes to spot a stationary vehicle in a live lane.

“Our new study shows that public trust on removing the hard shoulder has pretty much evaporated. Before any further schemes begin, we need an urgent and independent review into the safety of existing ones.”

When will the M20 Smart Motorway be open?

Kent's first Smart Motorway is expected to open in March 2020.

If the Department for Transport calls a permanent halt to future Smart Motorways, the six mile stretch on the M20 will be one of the last to be built.

How much does the M20 Smart Motorway cost?

£92million.

Where are other ones across England?

There are more than 100 miles of Smart Motorway across the country where the hard shoulder has been replaced and all lanes are running.

These are on the M1, M3, M4, M5, M6, M25, M62.

Read more: All the latest news from Malling.