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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.
Don't lights like these exist already? We have lights that change for you in southern Wisconsin. They do force you to slow down a little as you approach the light.
Visit BobtheKing.com it's perhaps the best thing I've ever made to waste your time with.
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.
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
I'll guess that the reason why is because a simulation shows this, not a real test. Traffic simulation has been a topic of much research, but as far as I'm aware, little convincing results have emerged... Simulations based on liquid flow do not work (they do not give anything like an average traffic), and those based on drivers modelization (ie, x % of 'aggressive drivers', y % of 'sloppy drivers', z % of 'careful drivers' etc) become incresingly complex and demanding with the scale of the simulation... I'm not aware of anything practical ever done with these (feel free to correct me).
In any case, if his adaptive system does work, it's a breakthrough. I've worked a few years back with people in charge of traffic and roads around Paris, and from what I've been told, nothing like this has ever worked better than static programming (with the exception of multiple programmings for different time of the day). From what I remember, even getting such programming right demands extremely experienced people. Of course, this might be specific to Europe where intersections are rarely perpendicular and often involve "creative" solutions.
Seattle has had self-adapting traffic lights at most major intersections for the last 5-10 years...
This is such a straightforward invention. I hope that similar inventions like this will see the daylight. It's all so straight forward.
people won't try to speed ahead anymore instead, they'll stick with a pack
I'm from a city in New Zealand (Hamilton) where we have a self monitoring system tied back to the City Council. Unfortunately it seems to be a little too smart, holding patterns that don't reflect the traffic. As a result, traffic changes its flow each day (drivers choose new routes) which further changes the trending and thus cancels the advantages you'd hope to gain. When the system is out or loops are cut (roadworks) the system reverts to timers/loops which seem to work better. Perhaps it's just when we add users the perfect system suddenly becomes imperfect...
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.
Jonathanjk.com
It's nice to see a traffic signal enhancement that will actually make driving more efficient and direct rather than the opposite.
I do not deploy Linux. Ever.
It looks like this system favors large volumes of traffic that flow through a city - the city dweller that is actually living in the city would get blocked by the lave volume of traffic that isn't stopping, and is instead just passing though on a direct route.
So the end result, is that the person who pays for the traffic-signals via taxes gets shafted - and a bunch of out-of-towners begin to use the city as a shortcut.
Great for people who live in the suburbs, but bad for the actual city dweller.
If I should miffed, it's because our small city has wonderfull routes for the yuppies to get to the local Wal-Mart - but those same yuppies won't stop in the core of our city to buy things from the mom-and-pop business that are paying for the nice routes.
Moneyed corporations, non-working 'poor' and criminal prisoners are turning productive citizens into tax-slaves.
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 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.
They can be used for evil just as easily.
Now I just need one that will recognize my motorcycle at 2am when no cars are around to tigger the lights for me.
I ride a supersport Yamaha YZF-R6. Weighs about 410 wet and I have problems triggering many stop lights, so much so that I have areas I don't ride when traffic is light because they never turn green for me.
Lets just hope this new system comes before we get flying cars. Seriously, sitting at red lights is one of the most boring things you can do. One light after another.
What I hate is when you have a good speed going and you can see the green light, then it turns red and you have to waste all the gas getting back to speed again. This new system maybe able to solve our gas problem. Less stop and go = less gas.
Mark
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.
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?
*blinking cursor*
Hey look over there, it's Mount Gullible! Seriously, that's an urban legend. In some places emergency vehicles use IR (read: not visible light) strobes to activate sensors on the traffic lights but that is the exception, not the rule. If you could somehow flash your high-beams with millisecond accuracy then you might be able to activate some of the sensors. I don't think most incandescent lights can turn on or off quickly enough to signal properly anyway. Finally, whenever the preemption signal is activated a (visible) light on the traffic light flashes. So you're most likely not activating anything. The light changes on its own, just like it does when you press the button to use the crosswalk at most intersections or when you press the close door button on elevators. 95% of the time, those buttons do nothing. 99.9% of the time (there is probably one random traffic light somewhere that changes because light flashes) flashing your brights will do nothing.
Karma: Meh (Mostly from meh.)
In my area traffic lights respond to a number of different input.
First off Lights are geared by the time of day. There many high traffic situations where traffic is high on certain streets so the lights regulate traffic accordingly.
The rest of the day the lights rely on a combination of pressure censors and lamination levels to determine how many cars are waiting at a particular intersection. In some instances pressure sensors are installed several yards before the intersection to being cycling the lights early.
Finally our city vehicles (with the exception of police, as we are county.) have triggers to over ride the lights at any given time. So ambulances and fire trucks always have the lights working in there favor.
"This is not new. It has existed in [town name] for the last [5/10/50] years. These guys are way behind [my country]"
Clearly the article is not about the same kind of inductive sensors that is available in almost EVERY COUNTRY IN THE WORLD. Just because your country has vehicle sensors at traffic lights doesn't make you special - everyone hs it. Ditto for traffic light schedules for different times of day. Ditto for remote controlling traffic flow from a traffic operations center.
Even Belgium, the place this research is from.
So clearly this is NOT what the research is talking about.
In order for induction to work, you would have to have a large quantity of metal in your finger.
So unless you're Wolverine, you're probably out of luck.
I thought that it would be a great idea to put an entire city's traffic lights on a private LAN system which monitored for traffic sitting waiting to go through the intersection. (Using whatever method to detect this which is cheapest.)
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.
Someone put a black hole in my pocket and now I'm broke.
Most major cities have this somewhere, somehow in effect. Weight sensors, radar, etc.
Around here (Cincinnati, OH) a lot of lights use a type of radar to "look" for cars. You can easily find them by turning on your radar detector.
The down side is that the radar only looks for stopped cars waiting at a light. Someone should have told those people about the doppler effect...
Get your Unix fortune now!
if(cars.dir(1) > cars.dir(2)) { // LIMIT is defined
if(green.dir(1)) {
if(time.dir(1) < LIMIT) {
light.green(1);
light.red(2);
}
else if(green.dir(1) != true) {
if(time.dir(2) < LIMIT - (cars.dir(1) - cars.dir(2)) {
light.green(1);
light.red(2);
}
}
Yeah, I know, it's incomplete and ugly but I just wanted to show a general picture. Yeah, this would work for small traffic situations, but, honestly, this could cause a lot of problems (bugs, etc.). Perhaps very limited "learning" traffic lights would be good, but totally self-adapting could cause lots of problems.
- dshaw
Note About the Code: Yeah, i did that in the little Slashdot comment box. It's ugly, unindented, and probably has nonsensical if/then cycles. Please let it be, since it's hypothetical anyway.
Just leave a few minutes earlier... People want to buy these 10 ton SUVs and watch DVDs and play video games in them, listen to satellite radio, drink their Starbucks and eat McDonalds. If you create a vehicle that is nearly as comfortable as your living room, why are you in such a hurry to get out of it? I drive a small Honda Civic, and people will gladly risk my life to whip across 3 lanes of traffic and make a U-turn into WalMart. Trust me, my time IS as valuable as yours, and I am not in that much of a hurry.
word.
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.
-- *~()____) This message will self-destruct in 5 seconds...
Most traffic laws (light times, speed limits, etc.) are made arbitrarily or based on generating revenue (shorter yellows to get you to run a light with a camera, unreasonably low speed limits). Designing roads and regulations based on what people actually do with them would help greatly.
In my city, the streets are in a 1-mile grid. The streets every 1 mile are major streets, and there are 1/2 mile streets that are collector roads. I'm not sure I'd want these at major intersections, but where a major street meets a collector road, it would work well. Set it up so that a large group of cars coming on the major road would turn the light green regardless, and then when there arent cars coming, the light would be able to cycle to the collector road and let everyone out.
The Doormat
If you're not outraged, then you're not paying attention.
Some colleagues of mine from Europe were in the states working for a few months. It wasn't prudent for them to purchase a car since they were here for such a short period of time. Since they also lived in the city, public transportation was fine, and walking got them to most places they needed. One night, after some late night partying got them hungry, they wanted to get something to eat. The only place that was open was the late night Wendy's, but it was just a drive-thru. One friend went up to the speaker/automated ordering booth, and stood there waiting...and waiting...before realizing as he stepped aside for a car to go through, that the sensor below allowed the attendant inside to know that there was a car waiting for ordering. He did what any person, half-drunk, hungry from partying would do...he stepped on the sensor and jumped with all his might -- to no avail. Eventually, he sobered up enough to actually walked by the window to talk to a real human. Ahhh...if it wasn't weight sensors, then the mere presence of a human standing on the pad should have activated it, no?
Linux at home
The article mentioned each junction being independent from each other, with no centralization. This strike anyone else as a possible emergent system? It doesn't appear to have the local communication that emergent systems do but it seems to me that you could get some interesting behavior out of this. Nothing terribly complex or anything but not necessarily predicted. The traffic flow could end up absolutly perfect for the situations, adapting to rush hours and eliminating traffic jams. Or, you could just get some directions having essentially no lights and others being always red. This would be no uber intelligent neural net of course but I would like to see the simulations and real-life trials.
/. a while back that had no lights and all the cars reserved a time to go through.
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
Assume (for this post) that these devices actually work and improve the efficiency of city streets. This is why you can't find them on your block:
(1) Safety. A lot of effort is spent proving that a traffic control device is safe. When traffic lights screw up and allow opposing green lights, people die. It is entirely unacceptable for a traffic control device to screw up.
So when a city is faced with buying a proven design or a new advanced design that improves efficiency but may be a liability concern, the city will go with the proven design.
I concede that the new system would be tested endlessly, but I claim that any complex system will have flaws that don't show up until deployed in the field. I've seen unbreakable unix systems crash. It happens.
I think that provable safety in this application can (and will someday) be done. I just wouldn't want to be the first city adopting it.
So another option to ensure safety is redundancy such as that used in some airplanes. That is, multiple independant systems working on the traffic problem, and if any of them fail the others will notice. Doing this right costs money, which brings us to point 2.
(2) Cost. My city really doesn't even bother fixing road problems. I went to Berkeley CA the other day and they had enormous potholes that were "fixed" by painting bright colors around them so they could be avoided. If Berkeley doesn't want to spend a couple bucks to patch a hole, then why would your little town bother to consider removing existing systems that cost hundreds of thousands of dollars and replace them with ones that probably cost more?
Further, why would you want your city to spend this money for a marginal improvement in flow? The answer is because some intersections are so terrible that you always are caught up in traffic. These intersections are the bottlenecks that hold up everybody, ones where 30% improved efficiency would be a blessing, which brings us to the 3rd point.
(3) This doesn't help the worst intersections. This switching system would be nice for those pesky lights in your neighborhood that always seem to be red when you arrive, and that you are always first in line and usually the only one to go through in your direction.
I claim that the intersections which could use a 30% improvement the most are those that would not be helped by this system. That is because no matter which side is getting green, every precious second of green light is being used by traffic. This is 100% efficiency, as measured by throughput / theoretical maximum throughput. You can not improve this system by watching for groups of cars, since there are always groups of cars coming.
This would be a neat feature on some intersections, but these intersections aren't the ones that DOT really focuses on improving. The effort involved in making small intersections intelligently switch lights isn't generally worth the cost of doing so.
That said, I'd like to see this in use in my neighborhood, and I'm glad that people are looking into solving traffic congestion problems.
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.
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.
And God I hate them. The cities that have properly timed lights and don't use these stupid sensors, have lower problems with speeding and "Orange Light" runners. Why? because if the lights are timed out to traffic flow staying at one constant speed guarantees you to always be green. In those areas that have the "smart" lights it's a constant traffic jam. Small side roads with a single car every minute, Short lights because backed up traffic is always over the jam detector (a loop device about 100 feet back from the light to signal backup.) Since in both directions there is always traffic over the top of them you get really short lights both ways and a blue ton of people pushing the light, drag racing to the next one to try and get 2 in a row etc. Then you add into the mix the "Left turn traffic" detectors .... ugh. Sometimes low tech is really higher quality and more intelligent.
No thanks. The problem here is that people drive on roads not on simulations. The benifit from these is not signifigant enough to justify the expense. In fact local studies I've seen done in California show that in most cases these lights actually increase polution not decrease it over the long haul.
I'm sorry, I'm to tired to be witty at the moment so this message will have to do.
Heh, that's funny, just yesterday I browsed around on arxiv.org (the famous repository of physics/math/cs papers) and saw the
original paper.
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.
Seems like using a Poisson Process (or other Renewal Process) to model the arrivals at a stoplight wouldn't be such a bad idea. Poisson Processes (and variations thereof) make great tools for mathematically modeling the arrivals of packets at router nodes, and this doesn't seem too different.
Just a random toss-out, but it seems like it'd be an ok starting point.
Heck with his system. I just want the computers that they use to monitor the sensors at the light to respond to you if you are there before the light changes. As it is, these systems currently seem to decide what will happen over 5 and sometimes as much as ten seconds in advance of their next step through a cycle. If you get to the red light for a left turn in that time window, the system will completely ignore you and make you sit there (often several minutes) while it goes through a complete traffic cycle and then finally acknowledges you and lets you make that left turn. There is simply no reason with the modern electronics in traffic control devices that this decision could not be made just a fraction of a second before the next step in the cycle. Such a system would be somewhat safer too, as it would be less frustrating to drivers and so would cause less people to cut through the intersections when the lights are against them.
I'm an American. I love this country and the freedoms that we used to have.
There certainly ARE such lights which can be changed to green simply by flashing your brights a few times. I personally have experimented on teh light in front of the hospital on the main road in Ft. Lewis, WA. I can find no other explanation, for the light works like a normal one, but in over a dozen tests in my and other cars, even in cases where the light had turned red (or even just yellow) a second before rapid-hi beam flashing commenced.
I suspect there are plenty more such lights, but they are distributed on the basis of perceived necessity, budgets, and all those other meta-variables which result in making all bureaucratic decisions appear purely capricious.
The Christian in me says it's wrong, but the corrections officer in me says, 'I love to make a grown man piss himself.'
Even if the bike was made of plastic and bubblegum you can always trigger the detector if you kill your ignition and then re-start the bike. The windings in the starter motor create a significant electromagnetic disturbance when cranking the engine.
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.
This model of allowing groups of cars through is the same as what naturally happens where there are no traffic lights, and cars and bicycles share the road. It is termed critical mass.
The term "critical mass" in this sense, was adopted from an observation made by American George Bliss while visiting China. He noted that traffic in China, both motorists and bicyclists, had an understood method of negotiating unsignalled intersections. Traffic would "bunch up" at these intersections until the back log reached a "critical mass" at which point that mass would move through the intersection. This description was related in the Ted White documentary Return of the Scorcher (1992) and subsequently adopted by the Critical Mass movement.
Perhaps the only difference with this traffic light system is it tries to preempt the "bunching up".
7 corners in bailey's crossroads, va definitely has some type of emergency reponse activated system like the one you mentioned above.
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.
One of these days, every vehicle will have an embedded RFID chip. Traffic Control systems will be designed to monitor these RFID tags. They will know if the vehicle is parked, or how fast it is moving. They may also know the source and destination for this particular tag.
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.
Sydney has had this for the over 20 years.
Around 2500 of the intersections in Sydney are linked together and they "marry" and "divorce" each other based on live statistical data as cars flow through the intersections.
It's a self-calibrating system. It has been exported to many countries.
The local intersection controllers measure traffic flows and adjust timings locally and also are linked to regional controllers that share statistics for an area and these regional controllers are all linked to the central monitoring facility in the city.
Google on the Sydney Co-ordinated Adaptive Traffic System (SCATS)
e.g. http://www.traffic-tech.com/pdf/scatsbrochure.pdf
So would a group of six mini coopers count the same as three ford explores? Length wise they would be about the same if they were tailgating?
I make my face look like this and concerned words come out.
Ann Arbor, MI has something like this in place. Late at night when there is no cross-traffic on the sensors, if you approach a red light and maintain constant speed at the speed limit (or below), it will turn green in time for your arrival at the intersection!
My old roommate was from there and told me about it, and I had a hard time believing him, but I went up there with him, and got to see them firsthand - they do work, but only at late night when there's no cross-traffic.
What traffic control signals need to do is a "greatest good for the needs of the many" calculation, so if a group of 5 cars approach from one direction and a group of 2 from the other, the group of 2 gets a redlight, and the 5 get a green.
-- You are in a maze of little, twisty passages, all different... --
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
It's no secret that our current government wants to force motorists off the road, either through excessive use of tax, or any other congestion 'saving' scheme that involves more money on our part. For this reason, I don't believe these devices will be used to turn our lights green on approach, but rather to red instead. It's a sad state of affairs, and unfortunately there's nothing that can be done about it.
here
This junction on Lochee road will go from green->amber->red->green straight away if there is no cars waiting on one of the other minor roads
All spelling mistakes are due to solar flares...honest
As an academic who uses simulations alongside formal modeling, statistical analysis, and experiments I can say that most academics know that simulation is a lousy way to "prove" a theory. Think of simulations as extended logic problems: the outcome is completely determined by the assumptions one makes and the inputs one provides to the simulation. No respected academic would suggest that simulations can "prove" the merits of a particular theory.
Simulation is, however, great for one thing: identifying the predictions generated by one's theory given a set of inputs. If you're trying to show that rule A doesn't necessarily predict outcome B, then simulation is useful. If you'd like to prove rule A does predict outcome B (i.e. almost any useful causal statement), then you need to follow up your simulation with empirical analysis.
Simulation says "If I'm right about everything, this is what the world should look like." It doesn't prove that you're right, but it does tell you what evidence you need to examine. Ultimately, if your theory can't predict the real world, it's of little import to most academics.
Make cheese not war 8:)
News for Nerds, stuff that ages for the others
What's the deal with news about stoplights?
Stoplights that show timers in Singapore?
Supposedly 'new' smart stoplights?
Here, in the midwest USA, for all of our many faults, for our political apathy, for our boring and endlessly flat terrain, one thing we do have is intelligent stoplights...
There are weight sensors in the road (and sometimes several distances of sensors) that determine when groups of cars approach an intersection.
It really does work fairly well, but there are limited gains in very high traffic situations.
This is both near and in Chicago, as well as in Iowa, and small towns all over the area.
AFAIK, its a very standard technology.
WhiteWolf666 an exBush supporter. All you new-school,compassionate,save the children Republicans can rot in hell
what our current traffic management head did is to disable the traffic lights and close intersections on a streth of road. instead u turn slots were placed around every kilometer. traffic eased up because cars do not stop on intersections anymore. there is a continuous flow of traffic.
a very no-tech way of easing the traffic. i would hope that they actually increase the number of roads where they do that. (but i think the problem is space on the road for the u turn slots.)
Live your life each day as if it was your last.
Sounds like my High School photo editor's car, a Yugo, stick shift. I would (alone) lift the BACK wheels off the ground to get past the parking brake. Then I would walk his car to a new parking spot while the engine was going pft...pft...
I'll admit to being on swimming/diving team and being able to leg press more than the car weighed at the time (I was leg pressing around 1200 lbs for reps.Shamefully my bench press was less than 10% that.)
It was lots of fun fun seeing him...(scratching head)"I know I parked here...Why is my car over there!" pointing behind a school bus 50 feet away!
The gag got old after quite quick. The second time I moved his car I was witnessed by some football players on the news staff. His car would be anywhere other than where he left it! At least they had the decency to not put it in the third floor stairwell as my Dad (and several of his friends) did to someone's Bug when HE was in high school!
Phil
Laugh, it's good for you!