The BBC has led an investigation into Smart Motorways and what happens when technology fails.

On Monday, April 22, a Panorama episode aired, giving insight into the safety fears which led to a ban on building more Smart Motorway.

The roads, which have no hard shoulder, stretch over 250 miles of the network and have faced heavy scrutiny.

The government have said new technology will make the stretches safer - using cameras and displays on gantries to close lanes and direct traffic in the event of a crash or breakdown. 

In the Panorama episode, the BBC spoke with families who were let down by the technology that was meant to save their loved ones.

In 2022, Pulvinder Dhillon, a 68-year-old grandmother, was killed after her car broke down on the M4 in lane four.

Ms Dhillon died after the car she was a passenger in collided with another just before junction 12 westbound on Monday, March 7, 2022. 

The incident saw a black Nissan and a white van crash at 8.40am, with one vehicle bursting into flames.

Two others were taken to Royal Berkshire Hospital for treatment as a result of the fatal collision. 

On the day, none of the smart motorways warning signs were active.

Ms Dhillon has been described by her family as a "beautiful, kind mother, mother-in-law, sister, Grandma and friend" who was loved and "respected by all she knew".

Speaking after the incident Mark Dunne of Thames Valley Police’s Serious Collision Investigation Unit previously said: “The woman’s next of kin have been made aware and are being offered support by specially trained officers, and my thoughts and the thoughts of Thames Valley Police remain with them at this extremely difficult time."

Barry O’Sullivan, 43, of Wixams - near Bedford - appeared before Reading Crown Court on Tuesday, February 13.

He pleaded not guilty to a charge of causing death by careless driving.

The prosecution in the case alleges that Mr O’Sullivan ran a Ford Transit Connect into Mrs Dhillon's car on the M4 near Reading.

A trial date has been set for February 24, 2025.

Panorama revealed that at least 79 people have been killed in accidents on smart motorways since they were introduced in 2010 - with seven coroners recently calling for them to be made safer.

National Highways have also estimated that if you break down on a smart motorway, you are three times more likely to be killed or seriously injured than on those with a hard shoulder.

The lack of a hard shoulder also makes it difficult for emergency services to access stranded and crashed vehicles.

Technology that is meant to keep motorists safe experienced 2,331 faults on the radar system, in 2023.

There were also 174 power outages in the six months to February 2024. The longest power failure was at Junction 14 on the M4, where there were no signals or sensors for 11 days.

In the last week, the government announced plans to make smart motorways safer by increasing the amount of 'safe zones' on the M4 between junction 8/9 and 12.

The process will see the M4 closed in sections to carry out the work, including a closure this weekend.

National Highways operational control director Andrew Page-Dove said: “Safety is our highest priority and our motorways are statistically some of the safest in the world, but there is still work to do as every death is a tragedy and every serious injury a life changed.

“They were introduced to provide extra capacity on some of our busiest and most congested sections of motorway, and the latest data shows that, overall, in terms of serious or fatal casualties, smart motorways are our safest roads.

“We are taking action to close the gap between how drivers feel and what the safety statistics show by increasing the number of emergency areas, delivering education campaigns, and improving the resilience of our operational technology systems.”

The Panorama episode can be watched on BBC iPlayer.