Smart traffic lights reduce fuel usage and lower emissions

Smart traffics lights reduce fuel usage and lower emissions

( -- Denso Corp. has designed the next version of 'the smart traffic light system'. By using messaging between vehicles and the traffic-light controller, better decisions about when to change signaling will help to maximize overall vehicle throughput at an intersection.

Today’s traffic light system collects sensor data from a loop of wire in the roadway to determine when the light should change. The car-sensing light stays green in one direction until a car wants to enter the intersection from the cross street. By reducing the time vehicles idle at a red light helps cut down on their emissions and fuel consumption.

Smart traffics lights reduce fuel usage and lower emissions
Smart traffic light system at intersection. Credit Denso Corp.

Denso Corp has proposed a system that uses short-range wireless transmitters in cars and elements of the road infrastructure. This would give traffic lights more information about upcoming vehicles and could change dynamically based on their speed, vehicle type, and relative volume of approaching vehicles. This would inform a stoplight of approaching vehicles and delay the change long enough to let them pass.

Denso has taken this proposed system one step further so that an intersection can achieve optimum flow of traffic. They have gone beyond the current signal-control algorithms, that employs averages of traffic flow, in order to adjust cycle times and light extensions to achieve the optimum traffic flow for any given set of approaching vehicles.

Denso Corp has been successfully implementing and testing both pre-empting red lights and extending green lights by using vehicle equipped transmitters and receivers in traffic lights at its Vista, California, research facility.

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Via: GreenCarReports

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Oct 27, 2010
i think the catch is that it will only work out if all approaching vehicles are equipped? OTher than that it is a nice system, that might work in a government dictated economy like china, i don't think americans in general are too fond of having their cars regulated by tracking devices etc...The american solution would probably be to wave your creditcard and the trafficlight will serve the highest bidder

Oct 27, 2010
Some sort of active/realtime traffic control like this is long overdue.

The waste involved in having to accelerate tens
-or even hundreds- of vehicles from a dead stop to 25, 35, 45, 55mph(serially) is staggering, and even at a $100 pricetag per vehicle, this, or a similar, device, would pay for itself very quickly, in fuel savings alone.

Unfortunately, this means that the device has to be totally fail-safe. Imagine the lawsuits. I would much prefer that the system be entirely external to the vehicles for this reason. Imagine the strain placed upon GPS systems to suddenly have to monitor realtime position of millions of automobiles.

Oh- wait, now I understand! Boy, there's some money to be made here, and primarily out of the pockets of taxpayers, as either Fed Mandate of equipment purchase, or Fed-funded Purchasing Program....

Oct 27, 2010
Caliban: GPS system components (=satellites) are send only. They don't receive anything from users. It's the same as with radio stations, it doesn't matter how many listeners there are. The in-car electronics would transmit their information to the earthbound traffic lights, not to GPS. The problem I see here is that someone could crack or exchange their in-car box to give them more 'weight' and that way to rig the system to give them more privileges. That has been seen in systems where busses can gain green lights by using transmitters. Then someone installed this transmitter to his car. But in the end he was caught and fined.

Oct 27, 2010
Someone stands to make a lot of money here, considering the large car to light ratio. The same information could be gleaned from a camera on the light without raising as many questions about privacy, with the added benefit of requiring less money to retrofit lights vs. retrofitting the entire car and truck fleet of the country. It would also be much easier to upgrade cameras as they could be upgraded individually without affecting the rest of the cameras, whereas vehicle-mounted transmitters and the light-mounted receivers would need to be standardized with newer models forced to be backwards-compatible. Also little mention is made of the confusion that would occur when vehicles without a device or with a nonfunctional device approach such a light. I agree that traffic-light technology needs to be improved, but the Denso Corp. design is not it.

Oct 27, 2010
As long as it doesn't lead to faster yellow lights...big money maker if you slash a second or two

Oct 28, 2010
These kinds of systems are already operational, using a magnetic sensing wire embedded to the road. There's several where I live and they seem too work fine, switching to green light whenever there's no crossing traffic as I'm approaching. I usually don't have to lift my foot off the gas pedal.

The trick is to place the mesh of wire sufficiently far away from the intersection so the system has enough time to work and count how many vehicles are approaching the intersection. Each type of car leaves a different signature, so it can guess fairly accurately whether you have a truck or a sedan waiting there. The only trouble it has is with motorcycles.

Oct 28, 2010
There are two methods already in use. The type using inductive wire loops are called "actuated" signals. There are also signals that send data to each other to let the next signal know when more cars are heading that way so that it can plan ahead. These are called "coordinated" signals. They are similar to the article except they don't use data transmitted from a vehicle, just signal to signal. There are 2 in Riverside CA where I am. The course I took on intelligent transportation systems discussed this topic. I will say, sitting at a red with no car coming in visual range is less irritating when you realize there is a method to the madness. I just keep repeating the mantra "for the greater good, for the greater good...". :)

Oct 28, 2010
Rather than rely on transmitters on cars, it would be preferable to put the tech in the traffic signals themselves. Using cameras already located at major intersections, employ image recognition software to 'see' the approaching traffic flow. Use this information to dynamically adapt the timing of signals at each intersection.
Communication between neighbouring intersections would allow each location to anticipate and 'adapt' to local traffic conditions, much as the 'swarm intelligence' of flocking birds and herding animals. (swarms are populations of simple agents interacting locally with one another, following simple rules without centralized control, resulting in "intelligent" global behavior)

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