Will you need a driving licence in the age of self-driving cars?

Driverless vehicles may seem unfamiliar now, but over the coming years you'll start to encounter - or even use them - on a daily basis. Will it mean the end of the driving licence and changes to the rules of the road?

It's not uncommon to see a squat white droid trundling along the streets of Greenwich, south-east London, as it delivers takeaway food to the borough's residents at 4mph.

In Paris and Helsinki, robot buses are shuttling passengers along city streets, while in Colorado an 18-wheeler truck drove beer 120 miles down a highway - without a driver.

Around the world, projects like these are under way to help develop the technology that will ultimately bring driverless cars and other vehicles to our roads.

But alongside the issue of whether they will work is another big question: how will pedestrians, cyclists and human drivers be kept safe?

Sales of self-driving vehicles are currently in the thousands, but some estimates suggest that they could reach 10m worldwide by 2030.

But that's just a tiny fraction of the more than one billion cars already on the road.

So, the challenge is figuring out how to accommodate both humans and driverless vehicles on roads, pavements and bike paths.

We've got several years, even decades, to get this right and self-driving vehicles that can operate without any human input at all are not on the immediate horizon.

Engineers are still working out how to handle some of the most difficult challenges.

Think about what happens at crossroads - when drivers and pedestrians arrive at the same time and use a combination of eye contact, gestures and intuition to navigate the junction safely.

This type of reasoning stretches the abilities of machines.

Other challenges include weather conditions that disrupt sensors.

And driverless vehicles will need to learn when to disobey traffic rules - for example, when an emergency vehicle needs everyone to move out of the way.

Right now, autonomous vehicles are still very much in the testing phase, "learning" how to deal with the unpredictability that is endemic to driving.

It's not something they have mastered and it's not uncommon for humans to have to take control in road tests to avoid accidents.

There have been a handful of high profile incidents, including a fatality involving a semi-autonomous Tesla car, with most down to human error - such as running a red light.