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."
Traffic Simulations (Score:5, Insightful)
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.
an added bonus (Score:4, Insightful)
SCATS (Score:5, Insightful)
Traffic Calming (Score:5, Insightful)
It's nice to see a traffic signal enhancement that will actually make driving more efficient and direct rather than the opposite.
Re:Weight Sensors (Score:3, Insightful)
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.
Re:Traffic Simulations (Score:3, Insightful)
This may actually suck for local users.... (Score:5, Insightful)
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.
In the years to come - Gas relief (Score:2, Insightful)
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.
Re:Weight Sensors (Score:3, Insightful)
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?
Re:an added bonus (Score:5, Insightful)
It sounds simplistic but this is the way people drive in New York City, by design. We don't have adaptive traffic lights (that I know of), but they wouldn't really do any good here because during the day the traffic flows at a pretty constant rate in all directions, and at night the lights are programmed to the speed limits on the major thoroughfares.
Believe me, a lot of study has been done into traffic management in major cities like New York, and tweaks to the system occur on a constant basis. But the "pack" is actually the desired effect in a city like this, where one pack of cars travels at the speed limit for a set interval before hitting a red light. Another pack follows them, and the pattern repeats itself on both crosswise and parallel streets. It's really the only way to both keep traffic moving and maintain speed limits. It also cuts down on red light running because you're not going to gain anything by running a red - you'll just end up at the back of the pack at the red light ahead of you. It similarly cuts down on unnecessary lane changes (which only slows traffic flow) because jockeying for position is not important.
Of course, there are still quite a few bad drivers here, but the fact is traffic does flow and adaptive traffic lights wouldn't accomplish anything.
Standard template for replies (Score:2, Insightful)
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.
Re:Motorcycles (Score:2, Insightful)
Already In Place? Yes (Score:3, Insightful)
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...
What is eveyones big ass hurry... (Score:5, Insightful)
Start with regular traffice engineering (Score:2, Insightful)
Here is why these aren't on your street (Score:5, Insightful)
(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.
Re:Weight Sensors (Score:4, Insightful)
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
Re:Motorcycles (Score:3, Insightful)
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
Re:Not a chance (Score:4, Insightful)
Re:Weight Sensors (Score:3, Insightful)
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.
Re:What is eveyones big ass hurry... (Score:1, Insightful)
Re:Traffic Calming (Score:1, Insightful)
There's a road here in College Station, Texas that's a perfect example of this. It's a nine-lane road, and there's a stretch of it with nearly half a mile between the traffic lights.
On one side of the road is Texas A&M's University's Northside Residence Area. On the other side is the Northgate district, which contains several bars. Thus, there are always students who are wanting to cross this street. Normally, this is done by playing a game of "Aggie Frogger". You pretty much have to, because the best legal alternative is to walk a quarter of a mile east to Houston Street, wait for the light to change, and then walk a quarter of a mile back, and that's HORRIBLY inefficient.
The combination of fast traffic and nearly-required jaywalking is an accident waiting to happen. We desperately need some traffic calming there.
In the UK (Score:3, Insightful)
Re:Great post (Score:4, Insightful)
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.
Re:In the UK (Score:3, Insightful)
In London, for example, 70-80% of commuters use public transport, yet the streets are still clogged up during rush hour because of the large number of people that insist of using their car whether they need it or not, eating up a disproportionate part of available space.
Thus slowing down the car traffic in London further would be a disaster for public transport that would undo work that the government has already spent hundreds of millions on.
Re:Weight Sensors (Score:5, Insightful)
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.
Re:Weight Sensors (Score:5, Insightful)
What part of the phrase "speed limit" is confusing to you? It's not a LOWER limit.