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Self-regulating traffic lights would improve vehicle flow


September 16, 2010

Researchers claim self-regulating traffic lights would decrease waiting time at red lights

Researchers claim self-regulating traffic lights would decrease waiting time at red lights

If you’ve ever been frustrated by stop-and-go traffic, you might have thought that traffic lights just don’t “get” what’s going on around them... and you’d be right. Traffic lights are programmed based on typical traffic patterns for the time and location, but are unaware of what’s actually happening at any one place or time (this wouldn’t include pedestrians hitting walk light buttons, or stopped cars activating sensors embedded in the asphalt). Not only is stopping and waiting for red lights irritating, but it is also a huge source of wasted fuel and extra CO2 emissions. Now, however, researchers have come up with something that may greatly reduce drivers’ periods in the “red light zones” – a system that allows traffic lights to monitor traffic in real time, and coordinate their signals accordingly.

Stefan Lämmer at the Dresden University of Technology and Dirk Helbing of ETH Zurich made a computer model of Dresden’s roads, in which the traffic streams flowed and merged not unlike water going through pipes. They then equipped the virtual traffic lights on those roads with sensors that monitored the local traffic flow. Using this input, each light calculated the expected number of immediately oncoming vehicles, and figured out how long it would have to stay green in order to let that traffic through.

The lights also communicated with each other and adjusted their timing based on what the lights up- and downstream were doing. There would be no sense in one light letting most of the traffic through, if it were all just going to be held up at the next one. Despite the fact that the resulting signal pattern appeared to be random and chaotic as compared to a pre-programmed pattern, the end result was a reduced waiting time of 10 to 30 percent.

Such a system would not only reduce traffic jams, but would also eliminate situations such as drivers having to wait at empty intersections, or lights cycling unnecessarily when no traffic is present.

Lämmer and Helbing are now working with a German traffic management agency to implement their system on real roads.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

I wonder if this kind of global thinking with local acting will really work in, say, Paris or Manhattan. Peoria, maybe.




This technology, while welcome, is nothing new. The biggest obstacles to this tech in my city (Brisbane, Australia) is bureaucracy. The state government owns/maintains some roads and the local government others. I have explored this problem with my local member of parliament. It seems their inability to work together means the environment, people\'s patience and time suffer. To date, no work has been attempted to rectify this seemingly simple to fix problem. Capitalism is probably the best political system in the world, but damn it\'s got some serious problems! Stefan Lämmer and Dirk Helbing, good work. It is through awareness and effort that these problems will be addressed. That and a lot of political will.


@Australian: Capitalism is NOT a political system. It\'s an economic one. Democracy, for example, is a political system. Political systems are based on laws while economic systems are based on markets. It\'s a huge difference. A political system based solely on capitalism (\"let the markets decide [people\'s lives]\") usually leads to Oligarchy, which is essentially the dystopia of Orwell\'s 1984.

Now that that\'s out of the way, long have I dreamed of a smart traffic light. It\'s embarrassing that it has taken this long for there to be a viable option. The traffic lights we have now are grossly inefficient and wasteful.


This is an idea who\'s time has come. If you think about all the gas wasted and smog produced by cars stopping and starting because traffic lights are not letting traffic flow. So many times I have seen one car at a light stop dozens of other cars when, if the light waited just a few seconds longer, the single car could have passed and not interfeared with all of the cross traffic.

Justin Scheller

I do hope these lights will take bicycles and light motorbikes into consideration. I have been stopped and unable to trip the sensor because I don\'t weigh a ton. I applaud this work as I have seen first hand dis coordinated lights that stop most of the traffic twice and thus cause much more traffic stoppage than they should.


Are you having a larf? The SCOOT and SCATS system do exactly this, and have been controlling thousands of traffic lights around the world for over 30 years. Please let the Germans know!

Graham Bodell

Traffic \"engineers\" --in reality, bureaucrats-- can easily address signal timing issues. They just don\'t want to, because to improve/optimize timing would essentially kill their pet projects, like spending cubic dollars on mass transit systems. How else to make people think that mass transit is the answer by having people sit in endless-seeming gridlock. That\'s exactly the case here in Honolulu, where a few years ago the bus drivers went on strike. Even with our 19th century traffic-signal technology the \"engineers\" improved signal timing to expedite the flow of traffic, assuming more cars would hit the streets. It worked. Traffic just flowed. Then, when the bus drivers returned to work, the signals went back to \'stupid\' mode. The mayor, upon being elected, promised to improve signal timing, but discovered his political golden goose in the form of a light rail system, so he promptly forgot all about his earlier promise.


some years ago whilst on a motorcycling tour of Europe I visited Cologne which had a system that used computer signs showing the speed you needed to maintain to get a green traffic light on the ring road. If you followed the small signs showing the required speed you got a green light at every set of lights


For America, this would best be addressed by Federal regulation and energy policy, backed by funding mandates.

No point in pushing for exotic expensive fuels of the future, and 60MPG standards, if we\'re just idling away gas wastefully sitting at \"dumb\" red lights.


For dense enough cities (like Vancouver where I am) I\'ve always thought buses should be fitted with a gizmo that talks to the traffic lights and keeps them green until the bus is through. If you\'re a driver right behind a bus, you could probably make it thru too, and if you were in front of a bus you\'d know you were fine. That way buses would only stop at bus stops, never at traffic lights.

They have this on Main street in Vancouver I believe, and I can\'t believe it\'s any more expensive than this system. No idea why they haven\'t rolled it out across the rest of the city.

Neil Salmond

Hope... and Maybe someone who can help Bangkok traffic problems..

Facebook User

Seriously, though, if it doesn\'t help LEFT TURNs then it\'s not news and a waste of time paying attention to. Why do you think one delivery carrier outright banned all left turns company-wide? I get so frustrated when I\'m behind ten cars turning left and only six or seven get through in one green left arrow cycle.


This technology is already well developed and has been for years. Your local authority just doesn\'t have the expertise to probably use it. SCOOT is a system Invented in UK to do just thos. It can even take inputs from environmental sensors like MOTES to keep traffic flowing if there is noxious gas build ups. The system can link up many sets of signals and allow them to work together.

Let me know if you want my company\'s expertise in traffic engineering to help you out.

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