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Self-Adapting Traffic Lights
Roland Piquepaille writes "If you're like me, I bet you hate moments when you're in a hurry and all the traffic lights seem to intentionally switch to red just in front of your car. Now, according to Nature, a Belgian traffic researcher thinks that traffic lights that respond to local conditions could ease congestion and reduce your frustration. His method would not give you the individual power to switch the light to green. But if you were part of a group of cars approaching a red light, inexpensive traffic-flow sensors would detect your group in advance and turn the light to green. His simulations show that such adaptive traffic control is 30% more efficient than traditional ways of regulating traffic. However, his system has not been adopted by any large city. So you'll continue to be frustrated by these ?%&$! traffic lights for a while. You'll find more details and references in this overview."
My city has weight sensors laid under the tarmacs, so it knows if there are cars waiting/approaching and switches lights accordingly, or if it shall let the other direction keep going.
The real problem only arises when there are too many cards coming from all directions, and the lights will switch to the "traditional method" that is based on a predefined interval.
It's a catch-22 - Gershenson admits that the benefits wouldn't be as large in a big city where the situation is much more complex than in his simulations, however only bigger city needs to/will consider such traffic control.
Rock that crushes, Paper & Scissors that don't matter.
When I was in San Jose, CA a couple of years back, they had a system up where sensors in the road would pick up cars at intersections. They then used microwave antennae to broadcast the information to lights further down the road. So if you were driving along at night with nobody else on the road, you would get long strings of green lights going your way.
Seattle has had self-adapting traffic lights at most major intersections for the last 5-10 years...
First of all, there are sensors under the cars that are standing right before the intersection. These types of sensors are installed just about everywhere there are stoplights. But if you pay attention, you'll notice that on this street, there are also sensors about 200 to 300 feet back from the intersection. There is a sensor under each lane. By the way, this is a major city street, with three lanes of traffic for each direction.
When driving during the day, there is a lot of traffic, and so you might wonder why in the heck it seems that the cross streets have much longer "green" times than you do.
When driving at night, you'll easily see why. There are usually only a few cars on this street at night. You drive, and you can see that all the stoplights ahead of you as far as the eye can see are GREEN. You drive, and immediately as you pass over the sensor that is 200 to 300 feet back from the stoplight, the light in front of you changes to yellow, and then to red. This happens at a rate that makes it impossible to remain at a constant speed and go through the intersection before it turns red. You'll either have to floor it (and even then it is doubtful whether you'll make it--the yellows are very short), or stop, which is what you'll end up doing.
Now that you're standing at this red light, and the cross street has a green, you'll wonder why you have a red and the cross street has a green, WHEN THERE ARE NO CARS DRIVING ON THE CROSS STREET! Now here is the interesting part. The light could be red for a minute or two, or you might stand there for a long time. As a matter of fact, I noticed that at all of the stoplights on this major street, they will remain red until a vehicle approaches on the cross street. As soon as a vehicle approaches there, his light will change to red and yours will change to green. At 3:00 am, it might take a long time before a vehicle approaches on the cross street. One time, I actually waited ten whole minutes before such a vehicle approached, and only then did his light change to red and mine changed to green.
Now I have been living here for four years, and I have driven down this street enough times at night to tell you that this isn't a casual observation and that I'm not just jumping to conclusions. Others who have driven down this road at night have mentioned the same thing, and I noticed that it never, ever fails. The sensors are all wired such that you will have to wait at EVERY intersection, until a vehicle on the cross street approaches, at which time he will have to wait, and then you get a green light. It's almost as if city workers wanted to play a practical joke and taunt drivers with green lights that remain green for any amount of distance, but only until you actually get near the stoplight. During the day, you don't notice it so much because there is so much traffic that everybody is stuck anyway.
Maybe, just maybe
..
Thet aren't out to get you, but in fact they screwed up the installation.
I've done a lot of construction and can see how this might happen, they screw things up all the time when they build things
You should contact whoever is responsible for the road a mention this.
US is currently preparing for a completely different thing - a more or less massive roll-out of red-light cameras (the thing where you get you car's photograph in the mail and a red-light ticket). As a preparation for this measure, stop lights are adjusted (most of the time the duration of yellow is simply reduced) in order to increase you chances of running red light, thus increasing the profit generated by red-light tickets. (This will also increase the fatality rate, of course, but this doesn't seem to be a reason for concern.) I'm amazed how much more often these days in California I see cars crossing intersection right under my nose even when I have green. A couple of years ago I'd see something like this about once in a month. These days I see it virtually every day. In this evironment it is highly unlikely (read - impossible) that US authorities will implement anything tha will to decrease your chances of running red light. Today they prefer to make money by decresing public safety, not by increasing it. So you can forget about anything like "driver friendly" stop light for a while.
There is at least one set of lights in my city that are timed rather than radar/rollover sensor triggered. The reason is that they are on the main road out of the city to the capital, where ideally there should be no lights/junctions. So the lights are deliberately timed to only allow traffic from the side junctions for a few seconds every few minutes.
But for all out madness, one cannot beat signal-controlled roundabouts. I don't know is anywhere else but Ireland insane enough to use these, possibly the UK, but it's rather run having to randomly stop at red lights while going round a roundabout.
The two main such roundabouts in Ireland are the Red Cow Roundabout in Dublin (the "Mad Cow Roundabout") and the Kinsale Road Roundabout in Cork (the "Magic Roundabout"). Best avoided - but usually unavoidable. Oh yes, I nearly forgot, the former now has a tram system travelling across it too. Fun fun fun.
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Oh man, this has been bugging me for about ten years. It seems that we already have a system with a built-in method of measuring traffic load via the sensors and a way to control that traffic via red-amber-green lights.
What we currently do with this system is impose on it an artificial set of rules that makes the lights change in a way that is smarter than just alternating every X seconds. But no matter how sophisticated we get, the whole approach is flawed in the same way that a spam filter with a fixed, unchanging set of rules grows less and less effective over time.
The article talks about partially "adaptive" traffic lights, but why not go all the way? I say unleash a bunch of totally Darinistic code modules on traffic lights. Have them mutate, and each generation the ones that score well (by reducing the traffic load they can measure) survive while the rest die off.
Clearly in the beginning the code modules would suck, but then you get a traffic system that is genuinely inhumanly efficient, and adapts to changing conditions. Why can't we have that?
This is what I think about every time I sit at an intersection with nobody coming in the other direction. Am I crazy?
I should buy some cement.
During high traffic times, they pretty much have to do the normal timed cycle to allow all traffic through.
But, many traffic lights don't need to be fully operational during non-peak times when traffic is low. Where I used to live, in Michigan, they had basic traffic lights, which they would switch to blinking mode in the evenings (the main road blinks yellow, to allow traffic through; the crossroad blinks read, and people proceed through when they can - after stopping).
In California, with an abundance of tax dollars, they use sensor based traffic lights. So, in the evening when I approach the intersection, it detects me, pauses for several seconds, then stops oncoming traffic to allow me through. I have to stop and wait, and oncoming traffic has to stop and wait. So, it's less efficient for all involved.
The net effect is that I seem to get stopped at EVERY traffic light I hit. Their expensive, over-engineered sensor lights don't seem to operate any better at peak times either.
Victoria is a very pedestrian friendly city and the ability move around using ones own two feet is cherished and rightly so. It is truly sad that cars trump pedestrains in your culuture.
Sorry, but a lot of Americans have to go to someplace daily for work/school that is just simply too far away to travel to as a pedestrian. Maybe in some of the giant cities you'd have a point, but it doesn't apply to everyone.
Personally, I live ~20 miles from my place of work, so i'm forced to use a car everyday instead of walking. However, I still have many options for getting some exercise - I can ( for example ) do light exercising in my living room, I can go to my apartment complex's fitness center, I can go to the YMCA, or simply jog on the nature trail across the street.
Many people don't (or can't) take the time to do something like that, but that doesn't make the car use the automatic cause of their poor shape.
Pherhaps this is why so many americans are fat asses?
Perhaps instead of being a smartass, you could explain the mystery of how many Americans that don't live within walking distance of everything still manage to stay in shape somehow. Boggles the mind, doesn't it?
Walking along city streets is not the only form of exercise, and "not being able to walk everywhere" is not the reason for people's poor health. Perhaps being forced to walk everywhere would help the matter, but it's certainly not a primary cause - as I said above, it simply removes one avenue for exercise from a list of many.
A friend of mine back in the day used to be a dealer for traffic light systems for Orange and Seminole Counties, FL (Orlando).
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There is a device on most intersections in the area that detect EMT and fire vehicles and turn all of the lights on that side of the intersection green as to clear traffic. These sensors hang in between the stop lights.
Another friend of mine claimed that he could flash his hi-beams at night and cause the sensors to think he was an ES vehicle. After speaking with the dealer I found out this guy was full of crap.
Apparently the system works like this:
Each vehicle has a strobe on top of the roof. When the siren/lights are activated, the strobe turns on automatically. The strobe flashes in a specific pattern and "activates" the sensor as it approaches the intersection. Behind the strobe however is an IR emmiter which sends a coded signal to the light which apparently identifies the vehicle and then gets logged in the system.
This allows them to track the time and number of the vehicle that went through the stop light turning everything green. It also lets them search for unauthorized uses in the system.
A somewhat unrelated point:
Seminole co is the second richest county in the state (other than Palm Beach). They have too much money. These peckerheads like to install traffic lights at intersections even if they are not needed...why? "to slow the traffic down" It pisses me off more than anything. The Central Florida area already has enough traffic problems and these waterheads are trying to slow things down... I guess they won't be happy until we are turned into the industrialized Star Wars planet of "Coruscant" and no one can move anywhere on the ground. http://www.starwars.com/databank/location/corusca
Its nukin futs!
Libertas in infinitum
I live in the poxy town of Swindon in England - home of the wierdest traffic management systems in the world, one of which is the Magic Roundabout (which I actually like, but timid drivers wet themselves at the thought of crossing it). On the north side of town, where I live, the new part of the ring road has about a dozen consectutive traffic lights on a road designed for fairly high volumes of traffic - all of which have sensors implanted in the road to detect traffic. The situation you get in rush hour is that when someone wants to get out of a side road, they trip their sensors, which eventually gets their lights green and the main junction is red. A chunk of traffic builds up at the red light and a gap appears in the road ahead. The next lights down then notice the gap and begin to think that it's a good time to let the people out who are waiting, with a consequence that by the time you get there these ones are red too. This repeats all the way up the road, so if you hit one red light, you hit them all.
You could be philosphical and think, "why do I need to hurry?". The answer is that I don't need to hurry, but the constant stop/start does reduce the mileage I get from a tank of petrol, and it just irritates me for various other unquantifiable reasons.
-- Intelligence is soluble in alcohol
The problem is that if every traffic light reacts only to input from sensors they traffic tends to get into a positive feedback state. This results in the total throughput on a road decreasing instead of increasing. I have been through this calculations several hundred times and no matter what method you use the result is still the same. It sucks rotten eggs compared to having all lights on a road set to fixed sync and having a floating speed limit to accommodate for congestion.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
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