Self-Adapting Traffic Lights 615
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."
Weight Sensors (Score:5, Interesting)
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.
Traffic Lights (Score:5, Interesting)
Old Technology (Score:3, Interesting)
So straight forward... (Score:2, Interesting)
Shows what I know (Score:2, Interesting)
I thought a majority of traffic lights were already predictive, I thought it was common sense to have this built into the technology when it was first created. If not as mentioned here but at least timed anyway to reflect busy and quiet periods in any given day.
On a side note, It annoys me as a pedestrian when you press the walk button, the green man comes on only when there is no traffic. Not of course when there is traffic and you need to cross the road in safety, thereby stopping the traffic.
Re:Old Technology (Score:3, Interesting)
Re:Weight Sensors (Score:4, Interesting)
At night, a single car coming will have the green light lit in advance assuming no other cars at the intersection.
During light traffic hours, a large group of cars will get the light over a single car, though the single car will get the light immediately after passing.
During heavy traffic hours, the light will cycle in sequence, with exceptions made for emergency vehicles.
Works reasonably well.
Re:Weight Sensors (Score:5, Interesting)
But not, alas, bicycles. There's one redlight back at my alma mater that doesn't turn unless you trip the sensor; it was either run it, or wait half an hour for a car to show up.
Traffic light true story. (Score:4, Interesting)
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.
This is not "old" technology... (Score:2, Interesting)
This isn't like normal weight-sensing or magnetic traffic lights. This system is designed to break the traffic down into chunks in such a way that no two chunks will approach the same light at the same time. This way, it can accomodate large amounts of traffic.
If you want to visualize how this might work, watch the episode of Futurama where they go to the planet of human-hating robots, where Fry and Leela are trampled by the robots going to and fro. The "chunks" of traffic would go past each other the same way the robots do in that scene, but regulated by stoplights.
Conspiracy Theory (Score:5, Interesting)
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.
Re:Traffic Lights (Score:5, Interesting)
The city around here got creative and installed radar to determine if someone's approaching a light. On almost every light in town. That shiny radar detector is now completely useless in town...
Not a chance (Score:5, Interesting)
And the people coming the other way? (Score:2, Interesting)
If a group of cars is travelling in one direction, this system will give them green lights ahead of them. When the group passes, the lights will eventually turn red in the same sequence. This is fine ... unless you're travelling in the opposite direction. You see, lights are coupled. If you have a green light to go straight, the guy opposite you also has a green light to go straight. So when the light behind you turns red, the light in front of the guy travelling in the opposite direction also turns red. If you turn lights green in favour of one direction, you're turning lights red to the detriment of the other.
What does the system do if there is enough traffic load to trigger this system in both directions? And if the system is only effective when there are no cars on the road, is it worth it instead of just using common pressure pads at intersections?
Re:Weight Sensors (Score:5, Interesting)
Often times a motorcyclist must wait until a car appears behind them to activate the sensor. Alternate action requires dismounting the bike and pressing the pedestrian button. In frustration some have waited several minutes in the hope a vehicle would appear to trip the light and when none have they finally felt safe to procede only to be stopped and written a ticket. It seems the only way to change the situation is to take it up with the street/highway dept. and/or the local government--not helpful hundreds of miles (km) from home.
Fortunately, there is only one sensor activated light in this town, but one of these days I'm going to be on a day ride and get stuck in one.
Re:Weight Sensors (Score:3, Interesting)
They detect older bikes better. Newer ones tend to be made from aluminum, which is non-ferrous. Steel (chrome-molybdenum, actually) bikes have a decent shot at it.
Traffic Light LAN system (Score:3, Interesting)
So instead of having all of those individual boxes out there that cost money to take care of on an individual basis - you just have a simple control box which sends and receives information. Think of it - each light detects if it is working or not and automatically calls for a human to come out and fix it. Lights become more coordinated than before because entire series of lights can all be set to green at one time. Emergency vehicles can carry wireless boxes with an encrypted password on it that tells the lights they are coming up to that they need to get through. And for those who misuse such things, the system could be rigged to monitor where each vehicle is located and if a vehicle is in two places at the same time the fake vehicle could be flagged and stopped by police officers.
How is the signal transmitted? Does the city have to lay hundreds of miles of new cable/DSL/Fiber Optic lines? NO WAY! All they have to do is to do the IP over the electrical lines and suddenly the entire set of traffic lights in any city is connected. You would have to install the proper boxes to listen for and accept the commands from the central server. But it is a lot less in cost than having to lay new communication lines. This might even be possible with wireless communications soon.
So you say: "What about large cities with several small cities within it or nearby? Won't they affect each other?" The answer is: NO - They won't. Remember that with TCP/IP v6.0 you have billions and billions of IP addresses to choose from. I think we can dole out a few thousand from this group for this purpose. Also, the power to the lights are (I believe) on a dedicated circuit which would effectively make all of the lights reside on a private LAN line not available to the public. (So someone would actually have to try to sabotage the lights rather than there being an accidental sabotage by a private individual on the same electrical line.) Filters can keep the two separate (ie: Public and Private IP over the electrical grid.).
Would it be bogged down? Not really. You don't have to be connected all of the time to the light. Only for the few milliseconds it takes to connect, tell the light to change orientation, and then disconnect. Let's say there are 100,000 traffic lights in your city. What do you do? You break it down into lots of 5,000 (so 20 servers). The average web server can handle 5,000 people per second while dealing out static web pages. This should be a snap because the information is a lot less than the average web page. The twenty servers are attached also to a single system which monitors all of the twenty servers by simply flipping between them like a TV monitor camera does. Or you could hire twenty people (one per server) to watch what was going on.
Similar to how monorail systems are monitored presently (only we throw out the static LED display and just use a monitor to display the light's status'), this system only has to keep track of if a light is working or out and can be programmed for different algorithms depending upon what part of the day it is. So rush hour traffic coming into the city is given preferential treatment over cross town traffic. At the evening rush hour the flow is reversed. Otherwise, lights respond according to the sensors. Keeping lights green for on coming traffic and red for empty streets.
Think of it - no more traffic lights that stay red for five minutes or more for no reason. Traffic lights that help you reach your destination. Block crooks from escaping areas by always turning their lights red and blocking their escape by always having the cross traffic moving through the intersection.
Timed vs. clever lights (Score:4, Interesting)
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.
Work well at semi-major intersections (Score:3, Interesting)
Possible Emergent Behavior? (Score:2, Interesting)
It would be really cool if each junction could remember traffic patterns (don't know exactly why but I'm sure there is a reason) as well as warn nodes around it about the situation. Maybe if it there is a lot of traffic and all the cars have to slow it could tell the node next to it to stop letting cars through for a little bit until the traffic at that junction cleared up. Or in the case of an accident, have other junctions not allow any traffic to pass to the scene. This would require some kind of communication system but it wouldn't have to be long range. You could even have a system of reporting patterns for statistics and research that jumps across the junction nodes until it reaches a collection point.
The whole system seems better than that automated traffic control mentioned on
Re:Weight Sensors (Score:1, Interesting)
How about a Darwinian approach? (Score:4, Interesting)
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?
Complain to the hiway department! (Score:3, Interesting)
Seriously, complain. Then get everyone else you know to do so as well. If things are not fixed within a month start a letter writing campaign. Include the newspapers and your congressmen.
Those sensors are adjustable. You just need to be annoying enough that they fix the problem.
Easier solutions for off-peak (Score:4, Interesting)
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.
Re:Shows what I know (Score:4, Interesting)
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.
Re:Weight Sensors (Score:5, Interesting)
A light along my regular commute had the same problem. I emailed the city's signs & signals department. After a few exchanges, they actually sent some people out to check the adjustment and mark with spraypaint the place where I should place my bike to trip the sensor.
As it turns out, they got it wrong--I eventually figured out I needed to be in a different position.
But the point is that it's worth being persistent--people may be willing to help, and there is probably some reasonable solution.
--Bruce Fields
Re:Weight Sensors (Score:5, Interesting)
-Rob
Re:Weight Sensors (Score:2, Interesting)
Re:Weight Sensors (Score:4, Interesting)
No Cop No Stop (Score:3, Interesting)
I made a telescoping probe(two broomsticks wrapped with coat hangers that i could extend to ~10') that I could use on most of the city streets as things were often very tight. Sometimes I would jump out of the car and go press the button. Other times I would yell at pedestrians to please punch the button. And never forget the pizza driver motto: 'No Cop No Stop'
I had those lights so down after several years of driving those streets that I could save several minutes per hour. May not seem like much these days, but I grabbed an extra 2$-4$/hour using these tactics.
Re:Weight Sensors (Score:3, Interesting)
I'd lobby for one of these if I was you. It's far more obvious to the casual biker where it is and how to activate it.
Re:well. (Score:3, Interesting)
I've sat at lights there for more then 5 minutes on occasions where no traffic in any direction goes and then you hear the sirens and see an ambulance wailing by. There's about 7 or 8 different traffic lights for all the different directions you can go on the intersecting roads so they definitely need a system like that in some places that can force reds so emergency vehicles can get by.
RFID should do it (Score:2, Interesting)
Sound like a routing protocol yet???
They will know the capacity and interaction of the entire traffic system at the micro level (ie between intersections) and adjust signals in realtime to optimize this flow.
Combined with auto-guidance systems, the vehicles will move smoothly to any final destination as singular entities or massive, intelligent recombining groups.
You heard it here first.
Re:Weight Sensors (Score:4, Interesting)
Not sure if it's purely timing, or distance sensoring, but either way, it seems to work - that is, piss the shit out of someone like me driving *only* 5-10 MPH over speed limit. After 10PM, the lights turn red on approach no matter what speed you are going.
The memory makes me quite happy to not live there anymore!
Emergency Service Sensors (Score:3, Interesting)
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!
Re:an added bonus (Score:3, Interesting)
I live in the poxy town of Swindon [swindonweb.com] in England - home of the wierdest traffic management systems in the world, one of which is the Magic Roundabout [swindonweb.com] (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.
Re:Already In Place (Score:4, Interesting)
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.
Re:Funny story about my european friends (Score:2, Interesting)
Once managed to do a drive-thru on my bicycle though, so I don't know where they draw the line.
Ah, SoCal...
Re:Funny story about my european friends (Score:3, Interesting)
Since we lived across the street, we walked back home, got in a car, and drove - to another eating establishment. We also called Taco Bell to complain. Did you know that you get a free meal coupon out of most any complaint to 1-800-the-bell? Hooray for free tacos!