A grandmother was killed after her car broke down on a “dangerously defective” smart motorway where technology meant to spot stranded vehicles was not working, a jury has heard.

Pulvinder Dhillon, 68, died instantly when a van hit the stationary Nissan Micra in which she was a passenger in a “high-velocity” collision in the fast lane of the M4.

Reading Crown Court heard that Dhillon and her daughter were trapped for six minutes, but safety technology fitted to motorways without hard shoulders had been defective “for five days” in March 2022.

National Highways, which runs the motorway network, was unable to trigger any “red X” signs on 14 west-bound gantries to close the outside lane to traffic.

Ian Hope, prosecuting, said Dhillon was in the front passenger seat of the car, driven by Rajpal Dene, her daughter, near Reading, Berkshire, when “for some unknown reason” the car “lost power”.

It came to a halt next to the central reservation with a dashboard warning light indicating a “system failure” on a “section of smart motorway without a hard shoulder”.

Mrs Dene turned on the hazard lights and tried unsuccessfully to restart the car before calling her son. He searched the internet in an attempt to find a solution according to the symbols on the dashboard message.

Read More: Grandmother killed in van crash after smart motorway tech failed