Autonomous vehicles could flash messages signalling their next move to nearby humans, using a system patented by US transportation company Lyft. The United States Patent and Trademark Office granted Lyft a patent this week for a notification system enabling self-driving cars to communicate with pedestrians, cyclists and drivers sharing the road. The system would see the windows of the vehicles turned into screens for written messages such as "safe to cross", "safe to pass", "yielding" and "warning turning left/right". Lyft's idea – which the company has given no indication it intends to develop further at this stage – comes at a time when tech companies are grappling with the issue of how to enable the transition to autonomous vehicles. "Drivers and pedestrians are accustomed to interacting in particular ways," said Lyft in its patent application. "Removing a driver from some vehicles can lead to uncertainty and miscommunication."