Who controls the traffic lights? How does it work?

Question

Who controls the traffic lights? How does it work?

Answer 1

Many lights are on timers, set to change at certain times, depending on the time of day.  Many have sensors buried under the asphalt.  When you pull up to the light, you trip the sensor with the weight of your car.  The light usually will change in less than a minute.  These are the two main ways that they work.

Answer 2

traffic lights R controlled by time relays set-up according to

traffic loads & jams for each direction. Some modern lights R

controlled by sensers which allow traffic for on the spot vehicles

Answer 3

No one controls it. It's computerized.

Answer 4

In Michigan, traffic control devices are set an monitored electronically via the Michigan Department of Transportation. They decide which interesections require lights, if they are set on a time setting or on a traffic control setting. Many lights are programmed to opertate quicker during peak traffic volumes then slower for lighter volumes then even flash yellow during limited traffic times (such as overnight between 10 pm and  7 am.

Not sure how they are controlled in your locale that is the case here in the US in the State of Michigan.

Answer 5

Thats like the cutest question. They are automated dear. Depending on timing and traffic volume.

Peace.

Answer 6

Traffic lights are on a timer. The timer is set but not always fairly.

Answer 7

In a city / township of ANY size (at least in California), they are controlled in THREE WAYS

1) Their primary control is the relay-box that sits at the intersection... it is on a timer to set the minimum times, but will also have buried sensors in the road-way.  A primary road with a small cross-road will STAY green for a LONG time, but when a car reaches the cross-road, it will trigger the light cycle.  The Relay box can also be programmed for different light cycles for different times of day... for example: Rush Hour.

2)  The Relay box is also linked by phone-line (or in some new boxes, by cell-phone) to a central computer which will permit direct control of a route or series of traffic lights.

3)  The Relay Box will also contain emergency settings... in a power outage, it will revert to blinking red, making it a four-way stop.

MANY modern traffic lights also have a sensor mounted on TOP that can sense a signal from fire/police/ ambulance drivers and clear the intersection for the emergency vehicle.

JUST FYI, my FIRST traffic signal in Phillipsburg, Montana was 3 light bulbs in ONE box... with 3 lenses on the four sides... so if you were going North/South the signal would look norma, but an East/West driver would see the lights upside down.

Answer 8

Traffic lights are autonomous usually but sets of traffic lights in London are phased by a central control so at rush hour they turn on Phase One which favours through traffic rather than traffic coming in from side roads.

Answer 9

traffic lights are on a timer

Answer 10

Most traffic lights are on timers,  set by civil engineers working for your local traffic authority.   Some lights take input from moniters on side streets,  staying green for the main road until someone needs out.  

The engineers measure the traffic flow entering the intersection from each direction,  then try to set the timers to allow enough time to let each side just empty before letting the next side go.   All their efforts are wasted by inattentive drivers who would prefer to talk on the phone than drive.

Answer 11

Dont' worry it's not me

Answer 12

They are either timed, or controlled by the traffic that is on the road and timers.

If you look down when you get to an intersection and see those lines in the pavement cut and filled with tar, those are sensors. Actually, they are big coils that pick up the metal on cars. Some people think that the feel the weight of the car, which is not true.

You would think in this day and age (21st century) that they would work better, though, huh?

Answer 13

Haha i have no idea but thats such a good question to ask!!

I'v heard though theres like little sensors in the road - like silver studs and they kinda sense when theres traffic going over them or something :S im not sure haha

Answer 14

traffic liights are controlled by a series of timed relays. Who controls them well generally the town in which there at unless its a county road then they do and highways are naturaly by the state

Answer 15

No, don't belive any of the above.

Watch the original film, The Italian Job, a giant computer that can be reprogrammed by Bennie Hill, so that Michael Caine can rob the bank.

Modern traffic signals have a mixture of autonomous (local computer control, timer based, varied accoring to the preset program for the junction or series of junctions) and centrally controlled system.

This to ensure that series of lights are phased.

Local sensors or traffic control can override for emergency or traffic management reasons.

Fire engines are fitted with transducers to trigger some sets of lights.

Answer 16

95% of the traffic lights in the world are timed (i.e. set) but on very busy or occasional 'different' intersections of roads, actual people sit and moniter + control them. But only few roads are like that. =)

Answer 17

Most lights are set on a timer.