Fighting Traffic With Smarter Traffic Lights

Do traffic signals need to be predictable? Researchers are experimenting with giving traffic lights a mind of their own, with the power to change with the flow of traffic, sensing when it would be most advantageous to be red or green.

Of course, some tinkering with traffic patterns already occurs, but researchers thought, what if the signal could sense the need at its intersection and respond to it autonomously?

But, as Rebecca Boyle writes at Popular Science, "...this "jungle principle" of every light for itself does not result in harmony, the researchers said. If each traffic light responds to its immediate demands, then all the lights will just react to the traffic coming from nearby intersections, which defeats the purpose of a smart network.

The solution is a decentralized approach that lets the traffic lights work together..."

Full Story: Giving Traffic Lights a Mind of Their Own Can Reduce Congestion



Are pedestrians impediments to the system?

This line from the Popular Science article has a foreboding ring to it:

"But variables like pedestrians in crosswalks, large crowds and vehicle wrecks can throw a carefully designed system out of whack"

Pedestrians don't throw the system out of whack. They are the system - just like all users of the road are. A true traffic optimization model would consider pedestrians, cyclists, and motor vehicles to be "traffic" and collect data on all modes of travel to optimize movement for everyone. Many cyclists already struggle to navigate a roadway system that, for example, does not sense the weight of their vehicle and trigger lights. If further engineering continues to show modal favoritism, it could only serve to isolate road users from each other and lead to an outcome that is not very efficient overall.

Read it again

That sentence is in a paragraph describing the existing system. To me, it sounds like this new method might be more adaptable, able to react to and accommodate pedestrians, rather than be disrupted by them.

If detectors are used that can tell the difference between a cyclist and a motor vehicle, then the signal could give a cyclist a longer minimum green time.

By the way, it's been a long time since weight detectors have been used. Most detectors work by detecting the magnetic field of the vehicle. Some use low power radars or digital cameras to detect traffic.

Can be applied to pedestrians as well

Based on several news reports, it appeared as if the independent sensors feeding into each of the self-organizing lights only recognized motor vehicles. However, after looking through an actual paper from Lämmer and Helbing, they do address plugging pedestrian sensor data into the model:

"Pedestrians could be detected by modern sensors as well and handled as additional traffic streams. Alternatively, they may get green times during compatible green phases for vehicles or after the maximum cycle time Tmax"

I don't see cyclists mentioned though.

Yes, I was referring to magnetic field sensors. Most bicycles contain ferrous metals, but do not "weigh" enough to trigger sensors as they are typically configured. I suppose I technically should have used conductivity but didn't think we needed to get into the physics of it.

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