Letting traffic lights think for themselves

Photo via Horian Varlan

The ways traffic lights handle oncoming cars can be a complicated science, and how well engineers manage that science impacts how much traffic we experience while driving. While most systems do their best to handle the flow of cars so that there is as little waiting at lights as possible, the real solution could be letting the lights do the thinking for themselves. A new patent on self-organizing traffic lights could reduce delay times by 10-30% which means drivers save on time, fuel and carbon emissions.

AlphaGalileo reports that in the "United States alone, delays linked to backed-up traffic cost nearly $100 billion each year, and waste more than 10 billion litres of fuel, not to mention countless human hours. And then there's all the extra CO2 and other pollutants spewed into the atmosphere. As developing nations become more industrialized, these problems will only grow worse."

But traffic lights that use the hive mind could make big dents in those numbers. Stefan Lámmer at the Institute of Transport & Economics of TU Dresden and Dirk Helbing of ETH Zurich have come up with a program that allows traffic lights to communicate with one another and come up with their own timing based on the amount of oncoming traffic. The lights are equipped with sensors that send information about traffic conditions to a computer chip, which then calculates what the flow of traffic in the near future is likely to be. It then determines how long the lights should stay green to minimize traffic pressure. What happens at one light is noted by other lights, so that the whole system is connected, all the lights working together to keep cars moving as efficiently as possible.

The article notes, "Despite the simplicity of these rules, they seem to work remarkably well. Computer simulations demonstrate that lights operating this way would achieve a significant reduction in overall travel times and keep no one waiting at a light too long. One of the biggest surprises, however, is that all this improvement comes with the lights going on and off in a seemingly chaotic way, not following a regular pattern as one might expect."

Earlier this year, BMW and Siemens unveiled a system of networked traffic lights that can communicate with nearby cars to warn them about road conditions, help them better use anti-idling features, but that can also learn about traffic patterns from those cars and adjust cycling times to optimize traffic flow, saving time and fuel. Their system would network not just the lights but the cars as well -- and could perhaps be expanded to have cars talk to one another to avoid accidents and make the roads even safer.

Of course, in terms of keeping traffic flowing, there's another far less high-tech option that eliminates lights altogether. Roundabouts have been proven effective at keeping cars moving safely -- Drachten, a small Dutch city with around 50,000 residents, removed almost all of its traffic lights and converted intersections to roundabouts. The change basically eliminated crashes at intersections and boosted bicycle and pedestrian traffic. The solution depends on drivers being courteous to one another and paying attention, but it seems to work quite well.

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