In baking hot San Jose, California, two men are lurking in the bushes at the edge of a deserted car park, waiting for a self-driving car.

They aren't normal pedestrians, or autonomy superfans. They are employees of the start-up Voyage - and they are going to test the car's ability to stop for people in its path.

This testing ground at the southern edge of Silicon Valley, is used by the company run by 30-year-old British entrepreneur Oliver Cameron, to make sure the cars behave as expected in different scenarios before they are unleashed on the retirement villages where they run as transport for elderly residents.

Voyage believes retirement villages are the perfect place for the initial roll out of self-driving cars. There are no children, few residents drive, and those that do are usually under the speed limit.

Jared Aguayo and Lucky Lui are operations specialists at Voyage. They don't just hide in bushes and walk out in front of driverless cars for a living, they're part of a team setting up this human obstacle course to make sure the company's vehicles are safe.