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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."
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.
Are you sure they are weight sensors? I was under the belief that those sensors worked on the principle of induction. They send a magnetic field up through the pavement, which induces a current in any metal vehicle above. That induced current, in turn, creates a magnetic field which is sent back down through the pavement to the sensor. Works in any temperature and will even dedict lightweight objects like motorcycles.
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.
You seem to be under the impression that city engineers (and their political bosses) would implement this if they thought it worked
Yes, from experience I can tell you that these people do not like traffic congestions and go to great length to reduce them, regardless of what any individual driver may think when he's sitting in his car and goes through a "red wave" (a set of consecutive road lights designed specifically to reduce speed [that may just be a french term tho]). Slower traffic here may mean smoother traffic there.
Of course that only applies to the people I've worked with, so granted, I'm generalizing.
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.
Try lining up your bike tires with one of the edges of the sensor when you pull up. Once I learned to do this I was able to reliably trip the sensor and get the light to change.
The sensors work off of magnetic induction (like a metal detector) and your bike just doesn't have that much metal to be detected. Positioning yourself along the edge of the road's sensor should trigger the light.
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 learned in my motorcycle safety class that if you extend your kickstand at a redlight it is more likely to trip the sensor.
Get up off your ass and raise up your glass!
My current bike won't engage the solenoid if the bike is already running. I don't have to shutoff the bike first. I just press the start button real quick and the light turns green. Since most lights are switching to camera sensors this isn't as useful now. Flash the lights a couple of times and the camera will pick it up as motion.
I know of one intersection in Ohio that detects a high beam and will switch back to green when you flash it, even if it just turned red. It might be a very old system that has some kind of primative basic light detector built in.
Well, they have the capability to detect motorcycles and bicycles, but often the street dept. lowers the sensitivity to the point that only vehicles larger than a small car are detected. This is well documented on many motorcycle discussion boards.
N redlitelaw/
Motorcyclists in Tennessee can legally run red lights because of this
http://www.motorcyclecruiser.com/newsandupdates/T
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.
The fact that more people are running lights couldn't possibly be the fault of the drivers could it?
Any camera system i've encountered will not flash unless your car is crossing the stop line when the light is red. If you are going the speed limit you should have no trouble making that stop safely. If you are in the intersection or on top of it when the light turns yellow you have nothing to worry about
If you can't see the value in jet powered ants you should turn in your nerd card. - Dunbal (464142)
The bike doesn't have to be ferrous. It just has to conduct electicity. Aluminum is actually better than iron for tripping a road sensor.
The trouble with bikes is their geometry. The bike's shape offers little capacitance for current flowing perpendicular to the wheels, so only a little bit of induced current flows before an electrostatic field builds up to counter the induced emf.
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.
Yes, its usually induction:
Howstuffworks: How does a traffic light detect that a car has pulled up and is waiting for the light to change?
Connecticut has these in many intersections.
I go crazy when strange drivers in front of me don't pull far enough up to actual go on top of the loop sensors. This is something that should be taught to all drivers.
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.
Works in any temperature and will even dedict lightweight objects like motorcycles.
you obviously have not ridden a motorcycle to any stoplights in Chapel Hill (or most of NC, for that matter). Today's generation of sportbikes (with emphasis on lighter weight & materials such as Al) have a hell of a time tripping these things.. if ever. Had someone once suggest a magnetic field induced by kicking the starter motor would trip the signal.. but it only works on rare occasion.
-'fester
-'fester
Many of the cities in Oregon have smaller sized inductive loops placed in the bike lanes. Typically, they're around 18 inches in diameter, and they have no problems detecting the presence of bicycles.
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".
Video detection is any iffy proposition in many locations. There are problems with false triggers caused by the shadows from adjacent lanes. There are also issues where low visibility conditions (nighttime, rain, fog) render them nearly useless. That being said, there are many cities using video detection, but many in the traffic engineering field will argue that they can't come close to the price/performance benefit of inductive loops, even given the initial high cost of loop installation.
"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. However, his system has not been adopted by any large city."
I am a traffic engineer, and traffic lights similar to what this Belgian traffic researcher describes already exist. They are called "actuated signals." They work as follows: Loops (not weight sensors, but magnetic loops) are placed in the roadway approx. 300 meters before the traffic light, then 200m, 100m, 50m and 10m. When the light is green for this path, every time a car drives over a loop(assume 300m loop), the green light time is extended long enough for the car to reach the next loop (200m), and so on and so forth until it reaches the 10m loop, where the green light is extended long enough for the car to travel safely through the intersection. Now, if the 300m loop is not reactivated every 3 seconds, the light "times-out" and will turn red once all vehicles have passed through the intersection safely (so if a vehicle is on the 100m loop, the light doesn't just turn red). Additionally, the light has a maximum green cycle time (sum of green and yellow light time), typically 58 seconds. So, if there is a never-ending stream of cars, the light doesn't remain green forever. I hope this clears things up a bit. Also, actuated signals are intended for minor arterials (major collector streets), not for principal arterials (expressways and large intersections).
"His method would not give you the individual power to switch the light to green."
Actuated signals do give you the individual power to switch the light to green.
pull along one edge of the sensor (you should be able to see the saw cut), and lay the bike down on its side across the pickup. Usually you don't have to go all the way down unless the sensitivity adjustment is really far out of whack - just tilting it some should be enough.
What the magnetic sensor is really measuring is flux through a wire loop that it's driving current around. This flux is proportional to the current it's using (which you don't control) and the surface area of the loop. As the signal is quite low frequency (60Hz - duh), any surface area enclosed at ground level by a continuous loop of conductive material would be essentially blocked (this is the standard "Faraday cage" effect. If the loops is higher up, the effect is to lessen the apparent area (since the field lines are curving).
A bike standing straight up is a line, with essentially no area, and the one part that might offer some area (the triangle of rear-axle and arms) is relatively far from the ground. Hence, it's nearly invisible. A bike on on it's side blocks a very large area (the wheels, the main triangle of the frame etc), and is so close to the ground that the signal is probably stronger than most cars. Thus, somewhere in between (ie, just tilting over) is usually enough to get it.
Still sucks if you're on a motorcycle, since they weigh too much to just hold at an angle (much less lay it down). I suppose one could carry a loop of wire and toss it down. But for ordinary bikes I've never found one that this won't trip (unless it's not magnetic at all, and those are very rare).
The Matrix is going down for reboot now! Stopping reality: OK. The system is halted.
Is this page wrong, then?
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
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... --
We actually take citizen complaints of this nature seriously, regardless of if it's someone driving a car or a bicycle. As I nentioned earlier, the only thing is that work load dictates how soon we might be able to address the complaint. We *have* to respond, and document our findings in every instance.
Marvelous system. I couldn't help but think we're behind the times when I experienced the bliss of never stopping at an intersection during a car ride through downtown. ;)
Where did all the street racers in San Diego go? I remember in 1999 and 2000 every friday and saturday night ~2000 cars would drive around Miramar and Mira Mesa. For the last 2 years I haven't seen them around. I did move to pb 2 years ago, so maybe that is why I have not seen them. Are they still around or have they finally been stopped? I have been to racelegal a few times, but there doesn't seem to be half of the people that used to come out.
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
"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." That's because you're speeding. The traffic lights are programmed with "green waves" that flow at the legal speed.
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.
This is a common misconception, in the "traffic world" when computing the optimum cycle length for a signal, the sum of the yellow light and green light is considered as one, after the yellow time has been determined. The proper way to calculate the length of a yellow light is as such, a driver shall have sufficient time to either:
a) travel through the intersection safely, before the light turns red, or
b) safely come to a stop (b/c there's not enough time to make it though the intersection safely)
So, what exactly do I mean by 'safely' you ask...
The yellow light should be long enough for a driver, who is traveling at the speed limit and within close range of the intersection, to pass safely thorough the intersection without accelerating.
Unfortunately, most traffic engineers either didn't learn this in school, or some moron thought they had a better idea to make them 1 second long. When a yellow light isn't long enough for someone to process that the light is yellow, and then make a clear decision if they can pass through the intersection safely, you get a "dilemma zone." A dilemma zone is when you can't safely travel through the light or safely stop before the light turns red (i.e. safely is not slamming on your brakes).
Spinning your tires (or wheels, I suppose) will get you off the line slower. When I'm driving like a maniac to get in front, I'm always careful to keep my rear tires just on the verge of slipping during a launch.
:)
Hooray for instant gratification, boo for pointing out that I'm only arriving at my destination 30 seconds faster as a result of all that stress-inducing behaviour.