Is a traffic light timed or is there a scale involved?

Question

My boyfriend says there is a scale involved when the light turns green. I think its timed. It makes more sense, like during the day its timed in shorter intervals, at night its timed in longer intervals...

Answer 1

A long time ago and maybe still today signals were timed. I have been in the big city and watched signals change when there was not a car in sight. Todays signals are usually controlled by a sensor, under the pavement, that senses a car that stops over it and changes the signal. The signal will stay set until a car enters an opposite lane and it will change to accomodate that car. The modern signals are computer controlled and can detect the cars in a lane and keep the signal in their favor till they all pass. It will then select another lane to go green. in this way it will not give a go signal to an empty lane as a timed signal will do.

Answer 2

Both are used and some at the same traffic light.....like if the sensor detects the car then it will count down like 15 sec till it changes if it doesnt detect a car then it wont change ......highway traffic lights use this at night

Answer 3

They are timed using some rather complex algorithms based on tons of collected data.

Scales are not used, mainly because the magnitudes of the forces involved with a car on concrete arent large enough. There are many other forces in play on a street (like contractive and expansive forces) that are much much much larger than the weight of a car.

Answer 4

Both systems are used. Some lights have a sensor in the road to indicate traffic, and some are timed so that traffic flows more easily.

Answer 5

I really don't know, but I think it may vary from state to state.