How bacteria could solve China’s rush-hour blues

As the largest city in southern China, with a population of around 13 million, Guangzhou has traffic so bad it’s legendary. One way to alleviate it would be to increase the intelligence of traffic lights — converting them from dumb beasts that beat out the same rhythm all day long into dynamic managers of vehicle flow.

And now two Chinese researchers have proved, at least theoretically, that insights borrowed from the lowly bacterium Escherichia coli could increase the throughput of a real-world traffic light in Guangzhou. No one knows what effect this could have if it were applied to an entire city, but it’s fitting that a solution from a class of algorithms that seek to mimic the collective behavior of organisms should be applied to the teeming masses of Guangzhou’s trucks and automobiles.

Traffic lights around the world, from Guangzhou to Geneva, are managed by computerized systems in a metal cabinet at the side of the road, which regulate the cycle of changes from red to green to red either through fixed time periods, or through sensors in the road that can detect when a car is stationary. Both options work well when traffic is low, less so during rush hour, as any driver will tell you.

The solution proposed for improving flow during high traffic periods is what’s known as a bacterial foraging Optimization (BFO) algorithm. The algorithm varies when and for how long a given light is red or green. So, for example, the algorithm has an almost traffic cop-like sense for which road at an intersection has a higher volume of traffic, and when to strategically deprioritize traffic that may be waiting on a less-used road. Simulations of a Guangzhou intersection showed that BFO-regulated lights reduce the average delay of vehicles by over 28% compared with those regulated by a fixed time cycle.

Internet:<www.bbc.com> (adapted).

Even though Guangzhou is the largest city in southern China, its bad traffic is nothing but a legend.