Image copyright Jaguar Land Rover Image caption One of Jaguar Land Rover's driverless cars

The UK's biggest car manufacturer, Jaguar Land Rover has been testing driverless cars on public roads.

The trials have been underway for several weeks on a half-mile route in Coventry city centre.

The vehicles rely on sensors to detect traffic, pedestrians and signals but have a human on board to react to emergencies.

Car makers and tech firms are competing hard to tap into the new technology.

Image copyright Jaguar Land Rover

Last October, the first public trial of some autonomous vehicles was undertaken in Milton Keynes where small self-driving pods - two-seater cars - were allowed to navigate around a pedestrianised area in Milton Keynes.

It was part of government-backed trials aimed at promoting more widespread use of self-drive vehicles by 2020.

JLR hopes its trials will help it to understand how self-driving vehicles interact with other road users and how to replicate human behaviour while driving.

It, and Ford, are also looking at systems which will allow cars to communicate with each other.

This means if one vehicle stops suddenly, its computers will alert the car behind.

JLR and Ford are part of the £20m UK Autodrive project, which also includes local authorities and insurers and is government funded.

Nick Rogers, the firm's executive director for product engineering said: "Testing this self-driving project on public roads is so exciting, as the complexity of the environment allows us to find robust ways to increase road safety in the future."

Analysis: Richard Westcott, Transport Correspondent

I was at a conference recently, full of the great and the good of the driverless car world and I came away thinking that it's going to be longer than I originally thought before fully autonomous cars are commonplace on our roads.

Why? Because of humans.

Researchers at the University of Southampton have been testing people in simulators and on test tracks for years. They've been trying to find out how good people are at taking back control when the computer goes wrong. I had a go in their simulator.

Anyway, here are their sobering findings.

"In simulated emergencies, up to a third of drivers of automated vehicles did not recover the situation, whereas almost all drivers of manual vehicles in the same situation were able to do so. In addition, research showed that drivers of automated vehicles took, on average, six times longer to respond to emergency braking of other vehicles compared to manual drivers."

Personally, I have no doubt that cars will eventually be fully automated. Too many big companies are investing too much money for any other outcome.

And the benefits could be world-changing. Cuts in accidents, pollution, congestion. Mobility for older people, people with disabilities.

But there are still plenty of significant problems that need to be ironed out before we get there.

An automated and electric vehicles bill is currently being debated in parliament to set out how new technologies will operate in Britain.

Major carmakers are seeking to head off competition not just from each other but also from technology firms such as Alphabet's Waymo, which is also developing autonomous vehicles.

Waymo said earlier this month that it will launch a ride-hailing service with no human behind the steering wheel.

It has been testing the fully self-driving cars on public roads in the U.S. state of Arizona.