Motorists behind the wheel of self-driving cars will be able to watch a film but not use their mobile phones under updates planned for the UK’s Highway Code.
The Royal Automobile Club said manufacturers need to ensure that people do not fall asleep at the wheel.
With self-driving cars, the person in the front seat will need to be available and ready, rather than in permanent command of the vehicle.
Drivers will be allowed to watch television programmes and films on built-in screens while using self-driving cars, but it will still be illegal to use a mobile phone behind the wheel.
Under the Department for Transport plans, congested, slow-moving motorway traffic will be the first situation in which self-driving cars are allowed to take over.
Steve Gooding, director of motoring research charity the RAC Foundation, said driverless cars “promise a future where death and injury on our roads are cut significantly” but there is likely to be a “long period of transition” while drivers retain “much of the responsibility for what happens”.
“Many of the systems that are being devised require the driver, perhaps, not to be in command of the vehicle but to be available to take back control if necessary,” he said.
“The government’s research has found it is far more distracting for people to be on a mobile phone — particularly if they’re having a conversation with someone and their mind is somewhere else — than if they’re in the vehicle, even if they are looking at a screen or reading a book.
“There’s a key role here for the auto industry to help people sitting in the driver’s seat.
“If they need to be staying alert and awake, we need to help them. Otherwise with the car on the motorway cruising along and driving itself, the greatest risk, I think, is they are going to nod off.”
He said the new rules were a sign that self-driving vehicles are coming and that the updated Highway Code showed it was close to becoming a reality.
“We will be able to travel in vehicles such as shuttle buses, or [have] a facility in a car we own that we can trigger when we are in slow-moving traffic on a motorway, which is looking like the first application that is going to come,” Mr Gooding said.
Users of self-driving cars will not be responsible for crashes under the proposed changes, and insurance companies rather than individuals will be liable for claims in those circumstances, the Department for Transport said.
Mr Gooding said that evidence from trials so far indicated that most accidents were caused by the other driver.
“If you are the driver and have triggered the automated system, I think it would be unfair to hold you responsible for something the vehicle did,” Mr Gooding said.
A full regulatory framework is expected to be in place by 2025.
There are no vehicles approved for self-driving on Britain's roads, but the first could be given the go-ahead this year.
The Department for Transport announced in April 2021 it would allow hands-free driving on congested motorways in vehicles with lane-keeping technology.
Existing technology on the market such as cruise control and automatic stop/start is classified as “assistive”, meaning users must be fully in control.
Transport minister Trudy Harrison said updating to the Highway Code will be a “major milestone in our safe introduction of self-driving vehicles”, which she claimed will “revolutionise the way we travel”.
“This exciting technology is developing at pace right here in Britain and we're ensuring we have strong foundations in place for drivers when it takes to our roads,” she said.
“In doing so, we can help improve travel for all while boosting economic growth across the nation and securing Britain's place as a global science superpower.”