A replacement for traffic lights gets its first test

So automotive engineers, motorists, and pedestrians alike would dearly love to know whether an alternative is feasible. Today they get an answer of sorts, thanks to the work of Rusheng Zhang at Carnegie Mellon University in Pittsburgh and a few colleagues. These guys have tested a way of ridding our streets of traffic lights entirely and replacing them with a virtual system instead, saying that their system has the potential to dramatically reduce commuting times.

First, some background. The problem that Zhang and co tackle is coordinating the flow of traffic through a junction where two roads meet at right angles. These are often uncontrolled, so motorists have to follow strict rules about when they can pass, such as those that apply at four-way stop signs. This causes delays and jams.

To solve the problem, Zhang and co use the direct short-range radio systems that are increasingly being built into modern vehicles. These act as a vehicle-to-vehicle communication system that shares data such as GPS coordinates, speed, and direction. This data passes to an onboard computer programmed with the team’s virtual traffic light protocol, which issues the driver a green or red light that is displayed in the cabin.