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Self-Adapting Traffic Lights

michael posted more than 9 years ago | from the small-pieces-loosely-joined dept.

Technology 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."

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Weight Sensors (5, Interesting)

fembots (753724) | more than 9 years ago | (#11004155)

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.

Re:Weight Sensors (1)

KinkifyTheNation (823618) | more than 9 years ago | (#11004175)

Every city i've ever lived in uses the same thing, I figured every city uses these?

Re:Weight Sensors (5, Informative)

Anonymous Coward | more than 9 years ago | (#11004190)

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.

Re:Weight Sensors (5, Interesting)

rawket.scientist (812855) | more than 9 years ago | (#11004214)

will even dedict lightweight objects like motorcycles

But not, alas, bicycles. There's one redlight back at my alma mater that doesn't turn unless you trip the sensor; it was either run it, or wait half an hour for a car to show up.

Re:Weight Sensors (5, Informative)

Mundocani (99058) | more than 9 years ago | (#11004390)

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.

Re:Weight Sensors (0)

Anonymous Coward | more than 9 years ago | (#11004283)

Ugh. In my city, I believe they use a simlar system. They have the sensors trained (or embedded) several car-lengths back of the intersection, so if there's a line up of say 2 or 3 cars the light will switch. The problem is people have figured out that all you have to do is stop 3 car lengths away from the intersection and then a lineup of one car will trigger a light change. So you have all these asshats that force a light change just for them. Iritates me to no end.

Re:Weight Sensors (1)

Alystair (617164) | more than 9 years ago | (#11004327)

Odd question, is this the same way the circular-button works the iPod? Via induction that is.

Re:Weight Sensors (0)

Anonymous Coward | more than 9 years ago | (#11004333)

that's one way of putting it... you could also say that the metal components disturb the magnetic field... and this field is what is being measured.
Of course it's the same thing physically.. just the induction and re-emission of a magnetic field is a little less intuitive... IMHO

Re:Weight Sensors (4, Interesting)

Nate B. (2907) | more than 9 years ago | (#11004341)

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.

Often times a motorcyclist must wait until a car appears behind them to activate the sensor. Alternate action requires dismounting the bike and pressing the pedestrian button. In frustration some have waited several minutes in the hope a vehicle would appear to trip the light and when none have they finally felt safe to procede only to be stopped and written a ticket. It seems the only way to change the situation is to take it up with the street/highway dept. and/or the local government--not helpful hundreds of miles (km) from home.

Fortunately, there is only one sensor activated light in this town, but one of these days I'm going to be on a day ride and get stuck in one.

Re:Weight Sensors (3, Insightful)

gniv (600835) | more than 9 years ago | (#11004201)

Are they weight sensors? I never knew. I thought they are electromagnetic or smthg. Anyway, they are everywhere in the US nowadays.

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.

roland is a fucking fag (-1, Troll)

Anonymous Coward | more than 9 years ago | (#11004202)

roland; you dick wad. fuck off with your own blog links. you used to post shit loads of stories that were useless and with links to your own sites to sell stuff and youve always posted with ur blog link, no doubt ur makin cash from the ads there, right? FUCK OFF WITH YOUR SPAM.

Re:Weight Sensors (4, Interesting)

ProfaneBaby (821276) | more than 9 years ago | (#11004208)

In Orange County (CA), the predictive/sensor lights are already in place, and are on date/time schedules, as well.

At night, a single car coming will have the green light lit in advance assuming no other cars at the intersection.

During light traffic hours, a large group of cars will get the light over a single car, though the single car will get the light immediately after passing.

During heavy traffic hours, the light will cycle in sequence, with exceptions made for emergency vehicles.

Works reasonably well.

Adapting Sensors for American Military (-1, Troll)

Anonymous Coward | more than 9 years ago | (#11004215)

Apparently, these sensors can detect clusters of cars and then can signal the traffic light to stay green or to change to green. I can imagine a military application for such a sensor.

We modify it for installation on an intermediate ballastic missile (IBM). Suppose that we fire it at a cluster of Chinese soldiers near a prison where Tibetan women and children are being held hostage [phrusa.org] . Naturally, the soldiers will disperse as the air raid siren sounds. However, the sensor will detect clusters of fleeing soldiers and signal the guidance system of the IBM. The IBM corrects course and aims directly at the largest cluster of soldiers, killing all of them.

Re:Weight Sensors (3, Insightful)

Stripsurge (162174) | more than 9 years ago | (#11004257)

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?

How's this for insightful (0)

Anonymous Coward | more than 9 years ago | (#11004335)

Roland Piquepaille is Jon Katz. Game. Set. Match.

Re:Weight Sensors (1)

Palal (836081) | more than 9 years ago | (#11004361)

There are some cities, which already adopted the technology. However, these sensors are not feasible for roads with large traffic flow, where timed lights are much better. On roads with large traffic volume, it is much better to create a timed cycle in order to provide the most volume throughput. I think that a bigger problem is the so-called "traffic calming measures", where signal cycles get screwed up by wannabe traffic engineers, and cars end up spending more time at stop lights, which in turn means less volume throughput, more burnt gas, and more angry drivers! Although they do have their benefits, I think that traffic calming measures have a very strong adverse effect on everyone affected.

Capacitance (1)

zoomshorts (137587) | more than 9 years ago | (#11004396)

The sensors can be either inductance or capacitance. Detecting changes in an electrical field. Bikes, alas, do not have enough metal in then to grossly affect either sensor, they are set to a higher threshold. I would go into the theory, but that is for another post, I suspect will be comming soon.

fp! (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#11004159)

Everyone must be stuck in traffic because I got the FIRST POST!

Why drive.. (0)

Anonymous Coward | more than 9 years ago | (#11004161)

... when you can walk?
Don't need to deal with traffic lights then!

Re:Why drive.. (1)

Freexe (717562) | more than 9 years ago | (#11004212)

why walk? when you can work from home?

Re:Why drive.. (-1, Troll)

Anonymous Coward | more than 9 years ago | (#11004259)

why work from home when you can have sex with small children?

Re:Why drive.. (1)

whiteranger99x (235024) | more than 9 years ago | (#11004220)

So I take it you take your chances going across the street, weaving against traffic? :P

Re:Why drive.. (1)

Zork the Almighty (599344) | more than 9 years ago | (#11004224)

Really ? Tell me, do you almost get hit by a car at every intersection ? Do you ever wonder why ?

Already In Place (3, Informative)

Grassferry49 (458582) | more than 9 years ago | (#11004162)

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.

Traffic Lights (5, Interesting)

AetherGoth (707621) | more than 9 years ago | (#11004173)

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.

Re:Traffic Lights (4, Interesting)

IO ERROR (128968) | more than 9 years ago | (#11004298)

Most traditional traffic lights are programmed to remain green for the major thoroughfare at night anyway, unless a vehicle pulls up from one of the side streets.

The city around here got creative and installed radar to determine if someone's approaching a light. On almost every light in town. That shiny radar detector is now completely useless in town...

Re:Traffic Lights (0)

Anonymous Coward | more than 9 years ago | (#11004367)

The city around here got creative and installed radar to determine if someone's approaching a light. On almost every light in town. That shiny radar detector is now completely useless in town...

Damn! I wish I had thought of that. I would patent it, sell it to every city I could, and become rich.

ROLAND PIQUEPAILLE HUMPS 12-YEAR-OLDS (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11004398)

lkasjdflkajslkf

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Traffic Simulations (5, Insightful)

lonedfx (80583) | more than 9 years ago | (#11004176)

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.

Re:Traffic Simulations (2, Insightful)

taustin (171655) | more than 9 years ago | (#11004211)

You seem to be under the impression that city engineers (and their political bosses) would implement this if they thought it worked. That assumes they want to reduce traffic congestion. I see no reason to believe that is their goal.

Re:Traffic Simulations (4, Informative)

lonedfx (80583) | more than 9 years ago | (#11004272)

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.

Great post (1)

EmbeddedJanitor (597831) | more than 9 years ago | (#11004364)

If you had not posted this, I would have.

Academics love simulations and models. They're great for proving theories. Problem though is that when the real world does not match the simulation model, then the theories don't work in the real world.

Independent traffic lights sound very unlikely to succeed since flowing traffic requires synchronisation of multiple lights to keep the flow going.

Old Technology (3, Interesting)

fervent_raptus (664099) | more than 9 years ago | (#11004178)

Seattle has had self-adapting traffic lights at most major intersections for the last 5-10 years...

Re:Old Technology (2, Interesting)

frisket (149522) | more than 9 years ago | (#11004198)

Traffic lights in the UK have had rubber-strip switch sensors embedded in the roadway before intersections since the 1950s. They have disappeared from sight but I believe they were replaced by a magnetically-sensitive buried strips at some stage in the 70s or 80s.

Re:Old Technology (1)

mikael (484) | more than 9 years ago | (#11004282)

Yes, I remember seeing the blade mark cuts on the roads. Unfortunately, these magnetic sensors weren't sensitive enough to detect cyclists. The worse case scenerio was when the traffic lights were programmed to remain at green for the main road unless traffic was detected on either of the side roads. So any hapless cyclist had to get off his/her bicycle, walk over to the pedestrian crossing, press the button, wait, then cross, and get back on his/her bicycle.

Re:Old Technology (1)

Hex4def6 (538820) | more than 9 years ago | (#11004303)

If you switch the bike off and restart the engine, that sometimes triggers the switch (Magnetic field from starter motor?)

You can also buy small devices that you stick on a bike, and I guess they create a magnetic field similar to the large mass of metal of a car.

What the fuck is a "self-adapting" light? (0)

Anonymous Coward | more than 9 years ago | (#11004336)

Can someone explain why we're calling these "self-adapting" traffic lights? Aren't they just "adapting"? Self-adapting makes it sound like the traffic lights are adapting to something inside itself.

What if... (0)

Anonymous Coward | more than 9 years ago | (#11004181)

...the weather's hot, hot, hot with a chance of passion? do they flash to the rhythm of the music?

So straight forward... (2, Interesting)

Lord Graga (696091) | more than 9 years ago | (#11004182)

This is such a straightforward invention. I hope that similar inventions like this will see the daylight. It's all so straight forward.

an added bonus (4, Insightful)

AnimeEd (670271) | more than 9 years ago | (#11004186)

people won't try to speed ahead anymore instead, they'll stick with a pack

Re:an added bonus (3, Funny)

WALoeIII (758807) | more than 9 years ago | (#11004199)

nah, I'll still speed.

Re:an added bonus (4, Insightful)

badasscat (563442) | more than 9 years ago | (#11004357)

people won't try to speed ahead anymore instead, they'll stick with a pack

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.

SCATS (5, Insightful)

Anonymous Coward | more than 9 years ago | (#11004187)

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...

Re:SCATS (0)

Anonymous Coward | more than 9 years ago | (#11004319)

This is what the Hamilton system is thinking at 9:30 in the morning:

"*Yawn* Oops, car comin'. Thet's a green Holden, eh. Must be Kiven. He's early today. Holy shut! The other three cars are comin' at once! What do I do? Bitter make the light green... okay, thet's the rush hour for the day. Time for a smoko, eh."

Then it shuts down until 4 pm, when the 4 cars in Hamilton come back.

Shows what I know (2, Interesting)

CrackedButter (646746) | more than 9 years ago | (#11004188)


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.

Re:Shows what I know (1)

TheAntiCrust (620345) | more than 9 years ago | (#11004351)

It costs a lot to stop traffic (gas, a lot of peoples time, wear on a lot of cars), it doesn't cost that much to make you wait (one slighty aggravated peon). Until that changes, prepare to wait.

I always felt weird when intersections would stop traffic to let me cross, I always felt like an idiot walking across an 8 lane road packed with cars waiting for my worthless ass to get across the street.

well. (1)

d3ity (800597) | more than 9 years ago | (#11004189)

Here in PA we have a system like that for emergency vehicles, late at night if you flash your high beams fast enough you can trigger a green light. Also i've noticed on the so equipped lights, if you stop before the light, and inch forward bit by bit, you can trip a green light. So dont we already have this?

Re:well. (1)

ubernoob22 (837558) | more than 9 years ago | (#11004205)

yeah i've heard of that too, but i'm not sure if that's actually true or not. it's always seemed to work for me, but this could be wrongly attributed to chance.

Re:well. (1)

itwerx (165526) | more than 9 years ago | (#11004248)

if you stop before the light, and inch forward bit by bit, you can trip a green light.

Creeping forward works (if there's no cross-traffic) on systems with multiple sensors because your motion makes it think there's more cars arriving thus giving your direction more "weight" and speeding up the cycle.

Re:well. (3, Informative)

gooberguy (453295) | more than 9 years ago | (#11004342)

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.

Here's an even simpler solution (0)

Anonymous Coward | more than 9 years ago | (#11004194)

get those cars off the road. Commuters are idiots. You should be living close to where you work.

Re:Here's an even simpler solution (1)

Grassferry49 (458582) | more than 9 years ago | (#11004279)

I live real close to where I work, but I still have to go through multiple stoplights to get to my job.

Re:Here's an even simpler solution (0)

Anonymous Coward | more than 9 years ago | (#11004293)

If you live close to where you work you should walk or cycle instead.

Re:Here's an even simpler solution (0)

Anonymous Coward | more than 9 years ago | (#11004371)

If you live close to where you work you should walk or cycle instead.

Unless your city has "intelligent" traffic lights, which will never sense your bike and force you to run the light.

Traffic Calming (5, Insightful)

Nonesuch (90847) | more than 9 years ago | (#11004195)

Most of the "traffic calming [trafficcalming.org] " enhancements to signals and lane markings are meant to slow down traffic, or even to introduce delays intended to drive commuters out of individual cars and into mass transit [motorists.com] (See AATC [io.com] ).

It's nice to see a traffic signal enhancement that will actually make driving more efficient and direct rather than the opposite.

Re:Traffic Calming (2)

lonedfx (80583) | more than 9 years ago | (#11004244)

It's nice to see a traffic signal enhancement that will actually make driving more efficient and direct rather than the opposite.

Traffic calming is often designed to make the traffic more efficient. It's not because the traffic one one road or another is faster that the traffic as a whole is more efficient. You have to take into account the impact of increasing the average driver's speed of one particular road on the other roads to which it is connected, and to which these roads are connected, and so forth. Calming traffic here often means smoother traffic there.

I guess it all comes down to what efficient means, but I suspect it's not the same thing for the driver and for the road staff :)

Re:Traffic Calming (2, Funny)

k4_pacific (736911) | more than 9 years ago | (#11004285)

On the main road in front of Wright State University, there is a series of traffic lights that are perfectly out of phase. I don't if its to annoy students who drive to fast or what, but I feel like a bit in a shift register whenever I drive through there.

I've wondered whether this could be done... (1)

Jeff DeMaagd (2015) | more than 9 years ago | (#11004196)

I also understand that traffic routing is a complex undertaking, so I do understand any trepidation that traffic engineers or city hall would have in setting this up. It also costs money too, though I bet a lot less than widening the road would.

I hope something like this does work as well as advertised and that it gets deployed. Simulations are one thing, I'd like to see a real world application.

Re:I've wondered whether this could be done... (1)

Jeff DeMaagd (2015) | more than 9 years ago | (#11004222)

And I realized I forgot to include the obligatory anti-Roland Papsmear rant. Too bad there's no checkbox based on article submitter rather than "editor".

Ancient news (1)

itwerx (165526) | more than 9 years ago | (#11004204)

This is really, really old news!!
There have been adaptive traffic lights for years (decades?). Most of them nowadays use cameras but some of the early ones using coils embedded in the road are still around.
(And no I'm not referring to the coils that are right at the light to detect waiting vehicles. You'll find the ones for adaptive systems between intersections at the midpoint of the block...).

So WTF, anyway? Is this guy related to Rip Van Winkle? He's got a hell of a lot more tech than that to discover out there!!! :)

This may actually suck for local users.... (4, Insightful)

zulux (112259) | more than 9 years ago | (#11004218)

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.

Re:This may actually suck for local users.... (1)

Solder Fumes (797270) | more than 9 years ago | (#11004343)

You can turn that around: the mom-and-pop businesses aren't getting many customers, so their tax revenue is far less than Wal-Mart's, so the yuppies ARE paying for the roadway.

Ignorance is bliss.... (1)

raehl (609729) | more than 9 years ago | (#11004345)

If your city is like most local governments, your local roads are paid for by property taxes paid mainly by residents, not businesses, unless you have a local sales tax, which is rare precisely because cities don't want to drive sales to the next town over.

As for Wal-Mart, it has just as much right to exist as stores downtown, more so if people wouldrather pay less for things sold in an EFFICIENT RETAIL ENVIRONMENT than pay more for things sold in an inefficient retail environment.

To get back on-topic, your whle premise is incredibly flawed - are you seriously suggesting that everyone from out of town will have green lights and everyone from in-town will have red lights?

News for nerds, comments by morons.

Ob (1)

Shishberg (819760) | more than 9 years ago | (#11004221)

I for one welcome our new intelligent traffic directing overlords.

What colour is '?' in? (0)

Anonymous Coward | more than 9 years ago | (#11004225)

"frustrated by these ?%&$! traffic lights"

What country is that? Mine only has Green, Amber and Red lights!

Traffic light true story. (3, Interesting)

rice_burners_suck (243660) | more than 9 years ago | (#11004226)

There is a major road by my house where all the stoplights are completely screwed up. It almost seems intentional during the day, but at night, you know the lights were designed to turn red when cars approach.

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.

Conspiracy Theory (4, Interesting)

acomj (20611) | more than 9 years ago | (#11004268)

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.

Re:Traffic light true story. (1)

WhatsAProGingrass (726851) | more than 9 years ago | (#11004276)

Just take a right, pull a "U" "e" and take another right next time. I'm sure that most cities have implemented the blinking red's and yellow's after a certain time. At Midnight, all the lights basically switch to blinking lights, which makes things much better, especially if you travel the main roads, cause they are all yellow.

Re:Traffic light true story. (0)

Anonymous Coward | more than 9 years ago | (#11004320)

re Traffic light true story. (Score:2) [slashdot.org]

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.


I noticed this when I was working second and third shift for several years; so I was either going home or going to work around 11:00 pm - midnight. Although I don't think I ever had to wait for 10 minutes (but it seemed like it).

The worst is the "no left turn" red arrows. I've sat through several cycles of lights without being able to legally make a left turn, even though there was no oncoming traffic.

It's obvious that these type of light patterns -- like many traffic laws -- have more to do with revenue enhancement than traffic safety [instapundit.com] .

Why the governments couldn't apply some of that facial-recognition technology they're so eager for to actually do something useful, like recogznie traffic, is beyond me. Wait, no it isn't. Never mind.

Re:Traffic light true story. (1)

Joel from Sydney (828208) | more than 9 years ago | (#11004365)

I just can't believe you waited 10 minutes at 3am for another car to show up and change the lights! If it were me, I would've waited 30 seconds, made sure there was no traffic approaching, and just gone.

Also, if you know where the sensors are and there's absolutely no traffic around, play a game of "dodge the sensors" ;)

Re:Traffic light true story. (1)

CokeBear (16811) | more than 9 years ago | (#11004387)

So do what I do anytime I encounter a red light and there is no traffic around: Turn right, make a U-turn, then turn right again. (Assuming that your jurisdiction permits right turns on red, as mine does). Also, do it really fast; its more fun ;-)

Uh... (1)

xenocide2 (231786) | more than 9 years ago | (#11004229)

This is generally how your traffic lights work; underneath the tarmac is a series of coils designed to detect cars. If anything his technique is to expand the sensors past the few yards they currently detect, a fairly obvious idea but generally not worth the gain over the status quo and intelligent consideration. Generally speaking traffic at night is just daytime traffic but lighter. You pretty much don't see roving gangs of traffic encountering a series of red lights.

This is not "old" technology... (3, Interesting)

JonLatane (750195) | more than 9 years ago | (#11004230)

But it is "common sense" technology.

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.

Control is the word, not efficiency. (1)

carcass (115042) | more than 9 years ago | (#11004238)

Has anyone ever noticed that traffic signals appear to simply impede the smooth flow of traffic? I think you could achieve the same "adaptive" traffic control capability by doing away with the lights and installing simple stop signs. Let the traffic control itself. I've been at innumberable intersections where the signals or human traffic directors have merely managed to create obstructions to flow, in both directions, tha wouldn't have happened without the attempt to "control" traffic.

In our haste to exercise control over everything, most stuff just slips through our fingers the tighter we squeeze (thanks, Leia Organa).

Re:Control is the word, not efficiency. (0)

Anonymous Coward | more than 9 years ago | (#11004291)

Exactly. There are some streets near my house that used to have stop signs at all the intersections. Said stop signs have since been converted to traffic lights and ever since, traffic is always backed up and congested. Everything flowed smoothly with the stop signs. All in the name of progress I guess.

Bidding for Traffic (1)

mbstone (457308) | more than 9 years ago | (#11004242)

All this presupposes that the govt. is interested in your time or convenience - ha. What would work is if drivers could place electronic bids indicating how many cents they would pay to receive preferential treatment at intersections. The traffic control software would compute which set of cars will pay the most and turn the lights green in that direction...

A good thing?, maybe not so much. (2, Informative)

s4f (523726) | more than 9 years ago | (#11004243)

They can be used for evil [sfgate.com] just as easily.

Motorcycles (5, Informative)

wpc4 (169892) | more than 9 years ago | (#11004245)

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.

Re:Motorcycles (0)

Anonymous Coward | more than 9 years ago | (#11004314)

I have this problem too. If you have loops under the road, you can often spot them (cut/resealed squares in road surface at the lights). Ride up onto the edge or preferably corner of the loop. It has a good chance of detecting you there, as the loops are more sensitive on the edges than in the centre. Also, make sure you have ferreous material in your wheels - steel/iron content - if they're magnesium or carbon fibre you may be plumb out of luck (magnetic detection).

How do you sense traffic (1)

BovineSpirit (247170) | more than 9 years ago | (#11004246)

People stop behind the senser, and then wait for the lights to change. Thermal camaras and magnetic sensors can't see cyclists. These systems are in use, and need a lot more work before they are really useful.

In the years to come - Gas relief (2, Insightful)

WhatsAProGingrass (726851) | more than 9 years ago | (#11004250)

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.

Re:In the years to come - Gas relief (0)

Anonymous Coward | more than 9 years ago | (#11004310)

Perhaps buying cars that are more fuel-efficient would be a more efficacious solution.

Car makers don't even need to pour money into R&D, just do as the Japanese and Europeans do.

Mandatory ... (0)

Anonymous Coward | more than 9 years ago | (#11004252)

In Korea only the elderly worry about traffic lights ...

What are mayors waiting for? (1)

spyrochaete (707033) | more than 9 years ago | (#11004254)

Traffic is a huge problem here in Toronto. I think that such traffic management systems would improve not only the efficiency of traffic flow, but the quality of life in general. People will be in better moods if they have to spend less time in the car.

I don't like sensors most of the time (1)

Private Public (812557) | more than 9 years ago | (#11004263)

the sensors are nice coming off highways and such and we have them out here in nowhere texas actually but when going in to the cities I prefer timed lights. in austin there are streets where the lights are timed nicely to allow you go get all the way down to the end of the street with nothing but green lights if you are going the right speed.

Not a chance (5, Interesting)

LanceUppercut (766964) | more than 9 years ago | (#11004299)

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.

WTF (1)

lelitsch (31136) | more than 9 years ago | (#11004300)

Ok, putting the sensors in the cars might be a new approach. But "traffic lights that respond ot local conditions" have been around for a least a decade. Even my back-of-beyond home town of 35,000 has them throughout the city. If you drive between 45kph and 55kph, you stop at two out of about 20 lights at most--no matter where you are driving. Heck, there were even classes about this at my university back in '88. For the connesseurs of long German words, the name of the class was "Verkehrslastabhängige Signalsteuerungssyteme."

But maybe the sumitterlives in a town with a large engineering and CS school and no #&*@ clue how to manage traffic flow--like I do nowadays. Yes, I am talking about University Park, PA or Champaign-Urbana, IL or Cambridge, MA, or ... .

Once again: Just because something doesn't exist in the good old US of A doesn't mean that it's not common in other parts of the world.

And the people coming the other way? (2, Interesting)

merdaccia (695940) | more than 9 years ago | (#11004307)

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?

Trip the lights whenever you want (1)

Fubar (1615) | more than 9 years ago | (#11004308)

Pick up your own Opticon [3m.com] device and turn the light green whenever you want.

Looks like it would be handy during rush hour...

Article poorly researched (1)

elronxenu (117773) | more than 9 years ago | (#11004312)

Australia has had traffic lights which vary their timing based on traffic conditions for many years (PDP-11s in the switch boxes beside the lights).

It's very unusual for Australian lights to operate on strict timing intervals when traffic flow data is available. It happens late at night ... when there is no traffic whatsoever, some lights will cycle through a defined sequence at the same rate ... but other lights will stay green continually on the more major road until some traffic arrives at the less major road.

adjust the timers (1)

jeffy124 (453342) | more than 9 years ago | (#11004318)

Philadelphia I can guarantee does not have this thing, but they have done some things to help. Chestnut and Walnut Streets are each three lane one-way streets that span the city from Front St (aka 1st) all the way to 63rd. They're big throughways for rush hour traffic into and out of Center City.

The traffic lights in the city are just plain old and the vast majority still run off mechanical timers and switches. If you're standing near one (ie, about to cross on foot) you'll hear the clunk inside the box. Very few lights (if any) operate off sensory equipment.

Anyways, along Walnut and Chestnut, from about 38th to 63rd for Walnut, 63rd inbound to 29th for Chestnut, the lights are "timed" such that you can quickly go from one end to the other without hitting red more than once or twice. There's no central controller, each individual light is calibrated. It works great, except of course when power goes out or one of those mechanical switchs get jammed, thowing a timer out of whack.

We have this.... (1)

TheMadRedHatter (716344) | more than 9 years ago | (#11004323)

We have this, really. We drive up to to the light and it self-adapts to red......

-- TheMadRedHatter

My city already has these (1)

Nine Tenths of The W (829559) | more than 9 years ago | (#11004330)

They detect if you're late for an appointment or hurrying to reach somewhere and then change to block your path

Already exists (to some extent) (1)

Duke Boo Boo of Ouch (664991) | more than 9 years ago | (#11004331)

Being a pizza delivery boy....(umm...I mean Unix sysadminrootrootlife 666), I've noticed that these type of lights are already in place where I live and work, but not so much in cities, where they are obviously needed the most. The way the lights I've experienced seem to work, the lights prior to the heavily trafffic'd intersections also regulate the flow of traffic. It's madd fun flying through traffic just to catch up with the group of cars in front of you to just squeeze through the light. And make sure you tip well. A lot of thought goes into getting a pizza to it's destination in a timely fashion.

Similar system in Phoenix (1)

philipsblows (180703) | more than 9 years ago | (#11004332)

We already have something similar here in Phoenix, though it is implemented in individual vehicles. If a single car is approaching a given red light at sufficient speed, the red light may be unsafely disregarded.

[I believe Phoenix is still number 1 in collisions or fatalities or something bad, as a result of red-light-running. If not, we will be again.]

dont give traffic lights too much intelligence.. (1)

Zurgutt (131637) | more than 9 years ago | (#11004337)

.. or the next thing that will happen is they get bored..

There are some in London already (0)

Anonymous Coward | more than 9 years ago | (#11004350)

Somewhere around Stratford... It was funny to see how they broke down generating a traffic jam for a couple of miles :)))

workaround (1)

morcheeba (260908) | more than 9 years ago | (#11004377)

So, if I understand the article, if I got a mobile home, and towed my XXL SUV, and behind that was a boat, I could become my own group and get all the green lights.

Or maybe I can buy a half-dozen of these [greenlightstuff.com] and tie them at 15-foot intervals on a long rope I drag behind my car.

This guys about to years late. (2, Informative)

VermifugeRT (461717) | more than 9 years ago | (#11004383)

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.

Standard template for replies (2, Insightful)

kimba (12893) | more than 9 years ago | (#11004399)

"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.
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