Traffic lights may get a fourth colour: ‘white’


Traffic lights date back to the 19th century, when the first one was installed in London, it had two colours, red and green, and was manually operated by a police officer. In the ‘20s traffic lights became more widespread in the United States and Europe, they typically had three colours (red, green, and amber). Now researchers propose introducing a fourth colour, white, for autonomous cars.

Transportation engineers from North Carolina State University have found that by adding an additional colour, traffic flow improves and congestion on the roads reduces. “This concept we’re proposing for traffic intersections, which we call a ‘white phase,’ taps into the computing power of AVs themselves,” said co-researcher Dr Ali Hajbabaie. “Granting some of the traffic flow control to the AVs is a relatively new idea, called the mobile control paradigm. It can be used to coordinate traffic in any scenario involving AVs. But we think it is important to incorporate the white light concept at intersections because it tells human drivers what’s going on, so that they know what they are supposed to do as they approach the intersection. And, just to be clear, the colour of the ‘white light’ doesn’t matter. What’s important is that there be a signal that is clearly identifiable by drivers.”

The researchers proved through simulations, that “even if only 10 per cent of the vehicles at a white phase intersection are autonomous, you still see fewer delays. For example, when 10 per cent of vehicles are autonomous, you see delays reduced by 3 per cent. When 30 per cent of vehicles are autonomous, delays are reduced by 10.7 per cent.”

Meanwhile, another study by Smart Mobility Living Lab based on a self-driving cars trial from London, suggested traffic lights could become obsolete in 20 – 30 years. As per Statista, the global autonomous vehicle market reached nearly $106 billion in 2021 and by 2030 is projected that the market will reach the size of over $2.3 trillion.