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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."
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.
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...
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.
I saw something more interesting a while back in Los Alamos. They had sensors (right near the nuclear lab) that detected you way in advance, and would change the light to green before you got to the intersection (no need to slow down). But they seemed to work only on weekends, when traffic was low.
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.
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
Erm... more likely the sensors you speak of are based on electric fields not weight. Driving the vehicle over the coil embedded in the road causes a change the inductance. (your car is a big chunk of steel).
There are somes limitations with this type of sensor. Its only has two states, there is a car here, there isn't a car here. No indication as to how many cars are backed up at each light. Also, once you're already stopped at the light, the damage has been done. This system it seems intends to anticipate problems before they develope.
Anybody else remember seeing something like this on discovery channel a while back?
"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.
I have seen that, but I have seen no reviews of it, and no one I ride with uses it...Seems like perhaps just a sham...Have to ask around to see if it's worthwhile.
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!
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.
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.
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.
There are devices out there that mount to the bottom of the bike to activate the sensors that work through inductance. I've heard of riders putting a large magnet under the frame. Running the starter is an interesting idea. With the engine cases being aluminum there is not as much magnetic shielding.
:).
I wonder if the starter on my 650 is large enough to do the trick. Alas, she's put away for the winter (well not so put away that I could get it going in a few minutes
"Insanity is doing the same thing over again expecting a different result."
As noted further up in the comments, there are generally ways you can position yourself so that you'll trip the signal, even with just a bicycle. There are usually visible cuts in the pavement where the sensor lives which you can use to figure out the right position. Google around and you should be able to find some discussion of the various sensor shapes.
Not much use when you're travelling, but when you're around home, at least, you should also complain to your local traffic engineers, who may be able to help; and by complaining you'll help out other motor- and bi- cyclists.
--Bruce Fields
You don't calculate how far away you would have to start braking; you calculate the worst-case scenario -- a big, heavy truck with shitty brakes in the rain.
"[Regarding the 'cloud,'] ownership was what made America different than Russia." -- Woz
Bicycle riders who want to stay alive stop if both the traffic light and pedestrian light are red.
Some bicycle riders fudge the traffic laws, but the laws are there to keep them safe and should be followed.
I have been commuting to work by bicycle recently and I would never run through a stoplight controlled intersection when both the traffic and pedestrian lights are red. I'll go hit the pedestrian button and wait for the light. Anything else is risking your life.
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.
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:)
Yet it never seemed to occur to you to just obey the speed limit...
The thing about timed streetlights is that they're calibrated for a given speed. If they're, say, calibrated for 30mph and they're 1/4 of a mile apart, they'll turn green every 30 seconds regardless of your speed. If you go "only" 5-10 MPH faster... you just catch a red light, and still don't get home any faster than someone who obeys the speed limit.
I.e., you'd think people would get the idea already that there is really no reward for endangering everyone around. Someone who stuck to the speed limit got home in exactly the same time, and obviously with less stress. Didn't need to use up extra gas accelerating and decelerating all the time either.
And yes, I do mean endangering. Due to the elementary physics fact that kinetic energy is proportional to the square of the speed, so is the braking distance. E.g., the speed difference between 50 km/h and 70 km/h is 40%, but the braking distance _doubles_.
Add poor visibility at night (you might not see a kid dashing to cross the street until he's in front of your beams), the driver _and_ everyone around being tired, etc, and I really _don't_ need people doing "only" 10mph over the limit at night.
And again, as you've noticed, it doesn't even get you home faster. It just makes you stop at the next red light.
But naah... for some people speeding is like _the_ proof of their manhood. Obeying the traffic laws or not driving like an irresponsible maniac, that's like admitting sexual impotence. Or worse.
Geesh.
A polar bear is a cartesian bear after a coordinate transform.
me driving *only* 5-10 MPH over speed limit.
What part of the phrase "speed limit" is confusing to you? It's not a LOWER limit.