Traffic lights that act locally can improve traffic globally, new research suggests. By minimizing congestion, the approach could save money, reduce emissions and perhaps even quash the road rage of frustrated drivers.
The new approach makes traffic lights go with the flow, rather than enslaving drivers to the tyranny of timed signals. By measuring vehicle inflow and outflow through each intersection as it occurs and coordinating lights with only their nearest neighbors, a system-wide smoothness emerges, scientists report in a September Santa Fe Institute working paper.
“It’s very interesting — the approach is adaptive and the system can react,” says mechanical engineer Gábor Orosz of the University of Michigan in Ann Arbor. “That’s how it should be — that’s how we can get the most out of our current system.”
An ultimate goal in traffic regulation is “the green wave,” the bam, bam, bam of greens that allows platoons of vehicles to move smoothly through intersection after intersection. When that happens, no drivers have to wait very long and sections of road don’t become so filled with cars that there’s no room for entering vehicles when the light does go green.