Connected Driverless Cars Can Improve Traffic Flow by 35 Percent

A fleet of driverless cars with the ability to communicate with each other can improve overall traffic flow by at least 35 per cent, shows an experiment by University of Cambridge researchers. The researchers programmed a small fleet of miniature robotic cars to drive on a multi-lane track and observed how the traffic flow changed when one of the cars stopped.

When the cars were not driving cooperatively, any cars behind the stopped car had to stop or slow down and wait for a gap in the traffic, as would typically happen on a real road. A queue quickly formed behind the stopped car and overall traffic flow was slowed.

However, when the cars were communicating with each other and driving cooperatively, as soon as one car stopped in the inner lane, it sent a signal to all the other cars.

Cars in the outer lane that were in immediate proximity of the stopped car slowed down slightly so that cars in the inner lane were able to quickly pass the stopped car without having to stop or slow down significantly.

"Autonomous cars could fix a lot of different problems associated with driving in cities, but there needs to be a way for them to work together," said co-author Michael He from St John's College who designed the algorithms for the experiment.

Additionally, when a human-controlled driver was put on the "road" with the autonomous cars and moved around the track in an aggressive manner, the other cars were able to give way to avoid the aggressive driver, improving safety.

"If different automotive manufacturers are all developing their own autonomous cars with their own software, those cars all need to communicate with each other effectively," said co-author Nicholas Hyldmar from Downing College who designed much of the hardware for the experiment.

For the study, the researchers adapted the cars with motion capture sensors and a Raspberry Pi - a small computer - so that the cars could communicate via Wi-Fi.

The findings were presented at the International Conference on Robotics and Automation (ICRA) in Montreal, Canada.