October 27, 2010 weblog
Smart traffic lights reduce fuel usage and lower emissions
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.
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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User comments
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....
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.
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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