Why MIT's plan to eliminate traffic lights isn't as crazy as it sounds

If vehicles could communicate with each other, they wouldn't need stop lights to prevent bottlenecks at intersections. That might allow twice as much traffic to use existing roads.

Carlos Barria/Reuters/File
Vehicles stop at a red light in downtown Shanghai.

Imagine being in a self-driving vehicle that gets you to your destination faster because it doesn't have to stop at red lights.

That could be possible in coming years, amid the advances in auto technology, including software that enables vehicles to communicate with each other.

A team of researchers from the Massachusetts Institute of Technology (MIT), the Swiss Institute of Technology, and the Italian National Research Council have designed a transportation system that doesn’t include stop lights.

Using mathematical modeling, the researchers illustrate how vehicles can be installed with sensors that send signals alerting other vehicles how far to stay from each other as they move in a four-way intersection – to ease the congestion at intersections, reported Computer World.

“An intersection is a difficult place, because you have two flows competing for the same piece of real estate," said Carlo Ratti, director of the SENSEable City Lab in MIT's Department of Urban Studies and Planning, and a co-author of the study.

“On the other hand, if a system has advanced technology and lacks traffic lights, it moves control from the [traffic] flow level to the vehicle level. Doing that, you can create a system that is much more efficient, because then you can make sure the vehicles get to the intersection exactly when they have a slot," he adds

Based on the concept known as “slower is faster,” the system the researchers are proposing is similar to boarding planes, according to the MIT media statement. Passengers hurrying to board a plane, are likely to create a bottleneck situation, increasing the amount of time it would take them to reach their seats. But if they move in a slow but steady speed, it will reduce the amount of time to get to their seats. Emphasizing the significance of consistent flow rather than quick speed, vehicles could avoid congestion at traffic lights in a similar way, the researchers say.

"You want the car to use the intersection for the shortest possible time," said Paolo Santi, a researcher in the SENSEable City Lab who is a member of the Italian National Research Council, and another co-author of the study, Tech Times reported.

"If you need to slow down the vehicles because there is a lot of traffic, you slow them down early in the road, so they approach the intersection at slow speed, but then when they cross, you use the best speed.”

The proposal is largely conceptual for now and would require a radical shift of the current infrastructure, which could take years to do, researchers admit. The system would also be at it’s most efficient with self-autonomous cars, by their calculation, it could allow twice as much traffic to use existing roads.

An abstract of the study on PLOS One says:

Results theoretically show that transitioning from a traffic light system to SI [Slot-based Intersections] has the potential of doubling capacity and significantly reducing delays. This suggests a reduction of non-linear dynamics induced by intersection bottlenecks, with positive impact on the road network."

"Such findings can provide transportation engineers and planners with crucial insights as they prepare to manage the transition towards a more intelligent transportation infrastructure in cities.”

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