via ScienceNews:
Complex-systems scientist Dirk Helbing and his colleague Stefan Lämmer from the Dresden University of Technology in Germany noted that when crowds of people are trying to move through a narrow space, such as through a door connecting two hallways, there’s a natural oscillation: A mass of people from one side will move through the door while the other people wait, then suddenly the flow switches direction.
“We thought we could maybe apply the same principle to intersections, that is, the traffic flow controls the traffic light rather than the other way around.”
Their arrangement puts two sensors at each intersection: One measures incoming flow and one measures outgoing flow. Lights are coordinated with every neighboring light, such that one light alerts the next, “Hey, heavy load coming through.”
The researchers ran a simulation of their approach in the city center of Dresden. The flexible self-control approach reduced time stuck waiting in traffic by 56 percent for trams and buses, 9 percent for cars and trucks, and 36 percent for pedestrians crossing intersections. Dresden is now close to implementing the new system, says Helbing, and Zurich is also considering the approach.
The whole point is to avoid stopping an incoming platoon. Gaps between platoons are opportunities to serve flows in other directions, and this local coordination naturally spreads throughout the system.
