Sustainable America Blog

A Future Without Red Lights?

Photo Credit: Great Beyond via Compfight cc

As any ecodriver will tell you, stop-and-go traffic is terrible for fuel efficiency. Some progressive cities and universities are addressing this issue by reinventing the way traffic lights work. The less time spent idling at stop lights the more smoothly traffic flows, resulting in better fuel efficiency and less gas wasted. Step into the future of the American traffic light, or lack thereof.

Carnegie Mellon University is doing substantial work in this field. The university has invested in Pittsburgh’s traffic future with their Traffic21 Initiative, a multi-disciplinary research initiative whose “goal is to design, test, deploy and evaluate information and communications technology based solutions to address the problems facing the transportation system of the Pittsburgh region.” Working with CMU’s Robotics Institute, Traffic21 created smart traffic lights that use cameras to sense traffic volume at an intersection, and technology that adjusts the timing of the lights to encourage smooth traffic flow through intersections. The result is less time idling at a stop light, less gas wasted, and of course fewer emissions.

According to Pop City, the initial results in Pittsburgh have been positive:

The pilot project, initiated last June, placed the smart lights along Penn Avenue, Penn Circle South and Penn Circle East. Among the benefits were a 40 percent reduction in vehicle wait time, a 26 percent reduction in car travel time and a 21 percent cut in vehicle emissions, the Traffic21 study reported.

With the help of Traffic21 and smart traffic lights, Pittsburgh is becoming a transportation city to watch, but they aren’t stopping at physical traffic lights. Scientists at Carnegie Mellon are designing a road-efficiency system called Virtual Traffic Lights that could do away with physical traffic lights altoghether.

According to The Atlantic Cities,

The basic world of Virtual Traffic Lights operates like this: as you approach an intersection, your car transmits data, such as location and speed, to other nearby cars. The virtual system processes this information for all the cars in the area, with the help of a lead car that changes every cycle, and determines your individual traffic signal. Instead of seeing a red or green light hanging in the intersection, you see it on your windshield and stop or go accordingly.

The system has a couple of main advantages. For one, every intersection with a car in it would have a (virtual) traffic light with this system. According to the Atlantic Cities article, only about 24% of intersections in New York City have a four-way signal. With a traffic light at every intersection, traffic safety could be expected to improve. The other advantage is traffic flow.

The Atlantic Cities article states that,

The algorithm that governs the virtual system can be written for total efficiency. If the system recognizes that no cars are coming from another direction, it can extend a green signal indefinitely. Likewise, at heavy intersections, it can give preference to the longest line of cars. Using similar technology to Google’s driverless car, the system can also recognize the presence of pedestrians and bicyclists, and orchestrate traffic to suit their needs.

Carnegie Mellon computer scientist Ozan Tonguz says the biggest obstacle to the technology right now is getting the government to test the system in a real-world setting. However, the Virtual Traffic Lights were recently tested in Porto, the second largest city in Portugal, with positive results. The flow of cars improved by 60% during a rush-hour scenario of one test.

While Carnegie Mellon University and Pittsburgh are making impressive headway with traffic light technology, other cites and universities are doing their own research and development on other exciting traffic light innovations. University at Albany School of Business Associate Professor Sanjay Goel has won a $378,375 grant from the James S. McDonnell Foundation to research the best way for traffic lights to communicate with one another and be more efficiently organized to keep traffic flowing and idling to a minimum. Goel plans to test the algorithms at selected intersections in Albany. Urban planning organizations like SPUR in San Francisco have also researched and support the retiming of traffic signals to reduce idling and congestion.

Sustainable America is committed to reducing idling in the U.S. in order to maximize fuel efficiency and decrease our nation’s dependence on oil. Smart and virtual traffic lights look poised to help us do just that! In the meantime, you can save gas and reduce your own idling time by turning off your car any time you’ll be stopped for more than 10 seconds.

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By the Numbers

Currently 50 million households suffer from food insecurity, meaning that family members cannot always meet their basic food needs.

10 million people a year could be fed through the recovery of just one-fifth of food waste.

Only 2% of food waste is composted or otherwise recycled—62% of paper is recycled.

Consumers throw out about 40% of the fresh and frozen fish they buy.

The U.S. produced 208 pounds of meat per person in 2009—60% more than Europe.

Low income commuters spend a much higher proportion of their wages on gas—8.6% versus 2.1% at $4 per gallon.

Food prices rose 35-40 percentage points between 2002–2008.

Americans consume 25% of the world’s produced oil, but our nation holds less than 3% of the world’s proven oil reserves.

The International Energy Agency says greenhouse gas emissions rose 3.2% last year, with a 9.3% increase in China offsetting declines in the US and EU.


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