Traffic light technology

[maniacalpha1-1]

I been meaning to ask this for months and always forget. I notice many red lights are smart and will vary the left turn signals/make other customizations based on traffic. How are they doing this, is it pressure sensors in the road, motion sensors somewhere, or what?

 

[vshah]

usually pressure sensors. sometimes a light won't trip if the lead car is too far back and isn't sitting on the sensor.

 

[lxskllr]

usually pressure sensors. sometimes a light won't trip if the lead car is too far back and isn't sitting on the sensor.

Small correction... It's magnetic, like a guitar pickup. They're getting away from that around here, and going with cameras. When you see a white camera on the cantilevered arm, it's most likely for sensing traffic.

I don't completely trust the the optical system. Seems like it would be a trivial upgrade to include a tag reader, and they'd be able to track the population across the country.

 

[Sluggo]

If you are truly interested, there is a HUGE thread over at SA Forums.

http://forums.somethingawful.com/showthread.php?threadid=3177805

 

[Red Squirrel]

They probably get the data from the NSA too, which they get from drones.

They should have a service where you pay a premium to the government so that lights turn green by the time you get there. It would be an amount of choice, so that if two people with that service come to the same intersection, the one who paid the most gets preference. May as well put the license plate and/or face recognition tech to good use!

Rich inpatient expensive car drivers could be the answer to the national debt.

 

[mmntech]

I've toyed with the idea of adding cameras to intersections. Monitored by a computer, it can see what's coming down the road and make a decision to change the light based on a more accurate view of traffic flow than in road sensors. Have the lights able to communicate with each other, now your laughing. 100% dynamic based on traffic flow as it is at that moment.

 

[FleshLight]

I've toyed with the idea of adding cameras to intersections. Monitored by a computer, it can see what's coming down the road and make a decision to change the light based on a more accurate view of traffic flow than in road sensors. Have the lights able to communicate with each other, now your laughing. 100% dynamic based on traffic flow as it is at that moment.

They do this already. They can also adjust traffic signal timing in real time as well.

 

[Aikouka]

Small correction... It's magnetic, like a guitar pickup. They're getting away from that around here, and going with cameras. When you see a white camera on the cantilevered arm, it's most likely for sensing traffic.

Yeah, I see far more cameras today than the sensors. I find that the method of sensing usually doesn't matter much, but rather, it's how the light is programmed that matters the most. Once you learn the way a light behaves, it's usually really easy to know what exactly is going to happen. For example, I almost always take a left off the road that I live on. The next intersection will always start changing before I can reach it if someone is waiting to turn left. So, if I see someone waiting, I don't waste my time accelerating. I have noticed that it doesn't seem to happen after about 8 PM, but sometimes it still has.

I don't completely trust the the optical system. Seems like it would be a trivial upgrade to include a tag reader, and they'd be able to track the population across the country.

Afraid that you're going to become a Person of Interest?

 

[HeXen]

They do this already. They can also adjust traffic signal timing in real time as well.

Wish they had that in my town. Nothing worse than sitting alone at a red light with absolutely no one within half mile view....except that 1 bored cop that's sitting just out of your noticeable view in a parking lot with lights off and eyeballing you with pure dare.

 

[SSSnail]

One thing I'm certain is that there are no technologies involved whatsoever when they set the lights rotation up here in SF, as if it's run by a monkey. You often see a section of the busy street where they'd program for the light behind another to turn green before the first one was. Basically, at a busy time, no one can go anywhere.

It's as if the lights are being run by monkeys, pretty much the same crew that runs the public transport system. Hmm, I think I might have to investigate this, wouldn't surprise me one bit to see a bunch of monkeys at city hall... :hmm:

 

[Phoenix86]

Even better is when intersections communicate with each other so you only stop once and get several green lights as opposed to stopping ever other one.. This can be timed well enough when you have known traffic patterns.

 

[olds]

They can put a man on the moon but I have to sit at a red light at 3 AM when there is no one else in sight!

 

[02ranger]

They probably get the data from the NSA too, which they get from drones.

They should have a service where you pay a premium to the government so that lights turn green by the time you get there. It would be an amount of choice, so that if two people with that service come to the same intersection, the one who paid the most gets preference. May as well put the license plate and/or face recognition tech to good use!

Rich inpatient expensive car drivers could be the answer to the national debt.

I think this is the best solution to the national debt I've heard yet.

 

[SSSnail]

They can put a man on the moon but I have to sit at a red light at 3 AM when there is no one else in sight!

But I bet you're in someone's sight. Run that light next time and find out. :awe:

 

[mmntech]

They do this already. They can also adjust traffic signal timing in real time as well.

Not here. Toronto has it's famous communist traffic lights. They're always red.
http://instantrimshot.com/

 

[Jeff7]

Small correction... It's magnetic, like a guitar pickup. They're getting away from that around here, and going with cameras. When you see a white camera on the cantilevered arm, it's most likely for sensing traffic.

I don't completely trust the the optical system. Seems like it would be a trivial upgrade to include a tag reader, and they'd be able to track the population across the country.

Yup. Loop detectors.
Inductive loop goes in the roadbed, a detector senses when a magnetic object (most likely a vehicle) is present, and adjusts the light's behavior accordingly.

Some work differently than others. I've observed, at least around here, that the lights will lock in their "decision" once the green lights change to yellow - so even if you get your car over the sensor, it won't trigger a left turn signal if you got there while the lights were cycling.
Other lights won't trigger until a car's sat there through a complete cycle.
Another left turn signal will turn on longer due to the presence of a second loop farther back - if a lot of cars are lined up to make a left turn, the light stays on longer.

Then it gets really damn cold and the systems stop working (relays start sticking, loops break, I don't know what), and then the loop detectors don't sense anything, so you have to sit and wait for the system's timer to expire, and after 2 minutes of just sitting there doing nothing, the thing finally changes.

They can put a man on the moon but I have to sit at a red light at 3 AM when there is no one else in sight!

Some intersections here are nice: They switch to flashing yellow lights along the primary road, and flashing red for the lower-volume road.

 

[Red Squirrel]

Not here. Toronto has it's famous communist traffic lights. They're always red.
http://instantrimshot.com/

There are some lights here that seem like they're always red, unless I happen to be coming from the perpendicular road, then that light will be red instead. :biggrin:

I was thinking though, they should change the rules pertaining to traffic lights. When the light is red, it should be like a stop sign. You stop, but if there's no traffic, you should be allowed to go. There are many times I find myself sitting at a red light for 3 minutes like a retard with not a single car in sight. The highway lights are bad for that. If anything they should at least change the timing at night. This is where traffic sensors would be handy as it could do traffic counting and as the count gets lower it could change the timing. Would need to be part of a network so all the lights/sensor data is all calculated as one.

Typically lights along a stretch of road like a highway are synced in a way that if you do the speed limit you should hit greens the whole way. At least, for one direction, it's not always possible to do it for both.

 

[jagec]

I been meaning to ask this for months and always forget. I notice many red lights are smart and will vary the left turn signals/make other customizations based on traffic. How are they doing this, is it pressure sensors in the road, motion sensors somewhere, or what?

They detect the desperation of the driver approaching the intersection. If they are desperate enough, BING! Long red for you.

 

[Jeff7]

They detect the desperation of the driver approaching the intersection. If they are desperate enough, BING! Long red for you.

The more sophisticated ones also have finer sensors to detect pressure in the bladder and rectum. Every sensed sphincter clench results in an additional 5 seconds on the timer.

 

[Mixolydian]

Around here, the traffic signals are preprogrammed most of the time. They don't sense traffic, especially during rush hour times. It's all timed.

During off-peak times, like during the overnight hours, it'll be sensor-based, with the "main road" always being green until someone from the other road arrives at the intersection.

As for the sensors embedded in the roadway, I think they use some kind of induction technology.