I've been thinking the same for the last year. Some lights are triggered by sensors in pavement. I've seen a string of 30 cars stop for a red light on a major road, just because one car approached from a minor side road...surely the traffic lights should have held the single car until the 30 cars were through the intersection...just think of the energy, pollution and wear that would be saved.

On a related topic..i'm told traffic engineers set up traffic lights to 'packetize' (my word) the traffic flow. The lights stop traffic, allow it to compress into a group of cars then send them down to the next lights...where they are stopped and 'grouped' again. This may be the best solution during heavy traffic times..but the rest of the time it actually encourages drivers to speed up to make the next intersection before it turns red. Why not configure the lights so that speeding means you get a red light, and driving the legal speed means you cruise through successive greens.

I think you are thinking too specific for this topic. If you want a truly time saving traffic flow system, then this is what I envision. It first starts out with the car. The car is equipped with a gps system, used to monitor distances, which works in tandem with the car's speedometer. As the car approaches an intersection, the car sends a signal to the traffic light as well as the driver’s intentions to turn right, left or go straight. The light then relays a signal back to the car indicating the current status of the light (color and timer). The system in the car then calculates one of the following options. If the car can make the light traveling at the current speed, then a green light flashes in the car telling the driver to continue at the current speed. If the car will hit a yellow light, then the driver will be given the necessary reasonable speed to make the light, or the driver will be told to slow down in advance and to prepare for a red light. This system has many advantages including: your car will achieve its optimal mile per gallon ration since no unnecessary accelerating, or idling will waste gas, lives can be saved since accidents caused by yellow and red light runners will be obsolete, and finally there will be no need to speed since the system will only output reasonable speeds in order to make the lights. However there are disadvantages as well. This traffic system does limit the driver's ability to "drive freely" on the road. Many people who don't want to be told how to drive will just shut the system off making it ineffective. Any suggestions, changes or criticism is always welcome.

I wonder how much of this annoying behavior by traffic lights is by design? I know of a street near where I live that is busy during rush hour (one lane each way) but pretty light the rest of the day. In the middle of the night, it is virtually empty. The speed limit is 45 and when it's empty, one feels like he/she could do 60 (which is a very bad idea due to some somewhat sharp turns and a large deer population in the area).

Anyway, there's about a 5 mile stretch that only has two lights along the way (and the two lights are about 50 yards apart). Coming down the road in the middle of the night, the light will be green. Without fail, it will change to red just as you come into range, without a car on any intersecting street . The only logical reason for this behavior is to try to slow cars down on the street. Just a thought.

This technology already exists. There are several "smart" lights in my city. They somehow observe approaching traffic from a hundred yards or more. In the night when there is little traffic, they always anticipate and turn green just when you want it to. It is super.

I don't know if they are able to communicate with other lights down stream. It seems that we certainly have the computer technology to do this. It would save a lot of fuel, pollution, and nerves.

I remember many years ago, as a child, a system of traffic lights in the South of France (it could possibly have been Nice or Cannes) in which a (variable)speed was indicated by a sign. If one proceeded through a green light and kept to the given speed each set of further lights would be on green.Now that was a good few years ago and I haven't seen anything similar since.

Why not just do away with lights and convert to round-abouts. I'm not versed in city planning or traffic engineering, but it appears to work great in Europe and in a few (lucky) locales in the U.S. Consider the benefits: 1. Continual movement that favors the primary direction (someone is always moving through it) 2. Slows traffic at intersection (vs. speeding through a green light) 3. Reduces ground-level ozone (from sitting still at lights). I'm sure there are many others I can't think of at the moment.

Obviously, this pattern may not work for areas with short-term extreme peaks of traffic off minor roadways (e.g. office parks, etc.) Also, perhaps I'm a tad cynical, but we would need to educate drivers and be prepared for a spat of accidents (low-speed thankfully) as drivers figure out how to use them.

I love this idea. I have wasted too much of my life waiting in the left hand turn lane for non-existant cross traffic. PROBLEM: County and city governments pay for and maintain these traffic control systems. They also generate significant revenue from traffic citations. :(