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."
Already In Place (Score:3, Informative)
Re:Weight Sensors (Score:5, Informative)
A good thing?, maybe not so much. (Score:2, Informative)
Motorcycles (Score:5, Informative)
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.
Re:Traffic Simulations (Score:4, Informative)
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.
Re:well. (Score:4, Informative)
This guys about to years late. (Score:2, Informative)
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.
Re:Weight Sensors (Score:5, Informative)
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.
just the opposite -- capacitive (Score:4, Informative)
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.
Re:Motorcycles (Score:5, Informative)
Re:Weight Sensors (Score:4, Informative)
Re:Weight Sensors (Score:5, Informative)
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.
Re:well. (Score:1, Informative)
Re:Weight Sensors (Score:5, Informative)
Motorcyclists in Tennessee can legally run red lights because of this
http://www.motorcyclecruiser.com/newsandupdates/T
Got them here (Score:3, Informative)
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.
Original paper at arxiv.org! (Score:3, Informative)
original paper [arxiv.org].
Re:Not a chance (Score:4, Informative)
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
Re:Weight Sensors (Score:5, Informative)
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.
Poisson Process (Score:2, Informative)
Just a random toss-out, but it seems like it'd be an ok starting point.
my pet peve (Score:3, Informative)
Re:Weight Sensors (Score:3, Informative)
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? [howstuffworks.com]
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.
Re:well. (Score:2, Informative)
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.
Re-start the motor (Score:4, Informative)
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.
Re:Weight Sensors (Score:3, Informative)
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
Re:Motorcycles (Score:2, Informative)
Re:Weight Sensors (Score:3, Informative)
Critical Mass (Score:2, Informative)
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 [wikipedia.org].
Perhaps the only difference with this traffic light system is it tries to preempt the "bunching up".
Re:Weight Sensors (Score:2, Informative)
Re:Traffic Lights (Score:5, Informative)
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.
Re:Weight Sensors (Score:3, Informative)
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).
Re:Weight Sensors (Score:1, Informative)
Sydney has had this for the last 20 years (Score:5, Informative)
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
Re:Already In Place - Yes (Score:3, Informative)
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.
Re:Complain to the hiway department! (Score:3, Informative)
Re:Weight Sensors (Score:3, Informative)
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. ;)
Re:Weight Sensors (Score:3, Informative)
Dundee, Scotland already has this (Score:2, Informative)
here [mapquest.co.uk]
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
Re:Weight Sensors (Score:2, Informative)
Re:just the opposite -- capacitive (Score:2, Informative)
Bizarre (Score:3, Informative)
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.
a different approach. (Score:3, Informative)
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.)
Re:Traffic Lights (Score:2, Informative)
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).
Re:an added bonus (Score:3, Informative)
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.