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Can Smarter Red Lights Let Cars Drive Greener And Save Gas?

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Can Smarter Red Lights Let Cars Drive Greener And Save Gas?

Source: GreenCarReports.com

We've all driven through--or waited a long time at--intersections that have car-sensing traffic lights.

Now Denso has modeled the next iterations of a "smart traffic light" system. It would use messaging between vehicles and the traffic-light controller to let the light make better decisions about when to change, to maximize overall vehicle throughput.

And that, in turn would reduce the number of minutes cars spent idling at traffic lights, cutting their emissions and their fuel usage.

In other words, cutting red-light time helps you go green.

Traffic light, meet oncoming car

Today's car-sensing lights stay green in one direction until a car wants to enter the intersection from the cross street, when the light is directed to change based on sensor data from a loop of wire in the roadway.

Denso's proposed system uses short-range wireless transmitters (think your WiFi router) in cars and elements of the road infrastructure. The field is broadly known as V2V (for vehicle to vehicle) communications.

Speed, density, and type of vehicles

Traffic lights that "knew" more about upcoming vehicles could change dynamically based on their approach speeds, the mix of vehicle types (e.g. compact car, tractor-trailer truck), and the relative volumes of cars approaching from any direction.

This would let a stoplight "know" that one single vehicle was approaching from a given direction, and delay a regularly scheduled change long enough to let it pass through.

Two tractor-trailers traveling one after the other could signal their presence to the light, allowing it to stay green in one direction long enough to let the pair (which together extend the length of five or six cars) pass through.

Data on whether a car was accelerating, braking, or flashing a turn signal would all factor into signal timing--including the duration of optional features like turning-lane arrows.

Optimum flow

Some express city transit buses already carry equipment that lets them pre-empt changing traffic signals, to reduce time lost waiting at red lights. The theory is that a bus with 50 passengers can and should take priority over 20 single-occupant cars.

Denso's model, however, goes well beyond the current signal-control algorithms--which use averages of traffic flow--to adjust cycle times and light extensions to get to the "state optimum" for any given set of upcoming vehicles.

The company has been testing both pre-empting red lights and extending green lights via transmitters onboard the vehicle and receivers in stoplights at its Vista, California, research facility.

Motorcycles, even bikes?

Ultimately, not only vehicles but motorcycles and perhaps even bicycles might carry signaling transmitters to take their place in the data flow.

Since engine idling at stoplights produces gas mileage of 0 mpg, and accelerating up to speed uses far more fuel than maintaining a steady speed, the savings come not only in time but also in reduced fuel usage and lower emissions.

How would you feel about a transmitter on your car that "talked to traffic lights"? After all, on this one there's a clear payback: Without such a transmitter, the stoplight couldn't stay green to let you through because it wouldn't know you're approaching.



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I like this idea.

Especially if done in a voluntary, non-intrusive, way.

The transmitters could be sold to the public without any government mandate or public money wasted on those units.

I'd buy one.

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The transmitters could be sold to the public without any government mandate or public money wasted on those units.

Don't even need transmitters. Just the typical road sensors.

I'd love to see something like this, but I feel that in the end, it will be implemented poorly.

Back in the '80s-'90s, there was a traffic light near Williamstown, NJ that used to have an advanced triggering system. I used to drive through it every night going to work... as you drove up to the light, it would change about 100 feet from you. Nice... but it did this by staying red all four ways... and you had to slow down to 10 mph under the speed limit as you approached, otherwise, you risked having to stop short... it would become a game of chicken with the cross street, as to who hit the light first and got the green light.

Granted, this worked pretty well for the era... it was better than sitting at a light for 5 minutes while nobody came through the other way... but it was very awkward... and sometimes it would backfire... essentially getting backlogged due to infrequent, but evenly spaced traffic, as the green stage was fairly short... if you missed the light, you had to wait for it to go yellow... then red... then green in that 100 foot distance... sometimes slow enough that you had to come to a complete stop... simply because you were not tailgating the dude in front of you.

So I kind saw that this light basically was conditioning people to drive unsafely to avoid getting caught at the light.

Sometime in the mid '90s... the DOT changed its programming to make it more standardized... one the stays green on the street I happen to use... I don't think I've been stopped by the light in the last 15 years. (I don't drive through it that much anymore).

Fast forward to 2010... I'm sure the traffic planners can do better with newer technology. But along with speed humps, bumps and chicanes, they could be programmed badly to attempt to slow traffic's speed, and this could foster bad habits.

I imagine a network of lights on a grid, say NYC, could be intelligent enough to allow for non-stop traffic in many areas later at night (remember, most NYC lights are timer only). During the day, well, all bets are off.

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This makes SO MUCH MORE SENSE than trying to reengineer society with fabulously expensive cars and rail projects. Traffic signal coordination and technology is cheap, easy, and very effective at reducing congestion and pollution.

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Finally someone gets it this would save more gas than 10 years sales of hybrids and lower fuel usage also :thumbsup:

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