Ford has been testing one approach that uses lights to indicate what the vehicle is doing and what it will do next. It’s part of the company’s research into developing a communication interface that will help autonomous vehicles seamlessly integrate with other road users.

To ensure testing was as realistic and natural as possible, the company created the “Human Car Seat” that it installed inside a Transit Connect van. Designed to look like an autonomous vehicle, with the driver hidden in the seat, observers could more effectively gauge responses to a roof-mounted light bar that flashed white, purple and turquoise to indicate when the van was driving, about to pull forwards and giving way.

The latest testing, which complements research already carried out in the U.S., was conducted together with Chemnitz University of Technology, in Germany. Researchers expanded the tests to check the effectiveness of two other colours, in addition to white; a rooftop location, when the U.S tests had the lights placed on the top part of the windshield; and situations with further distance, showing the lights up to 500 metres away.

It showed that 60 per cent of the 173 people surveyed after encountering the Transit Connect thought it was an autonomous vehicle. Together with the observed reactions of a further 1,600 people, turquoise – more noticeable than white and less easily confused with red than purple – emerged as the colour that was preferred. There was also a high level of acceptance and trust in the signals, providing a basis from which researchers can further develop and hone the visual language.