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123 Comments
- cypher35, on 10/12/2007, -7/+151"Not how you would think!"
funny, this was exactly how i thought it worked... - inactive, on 10/12/2007, -14/+46They forgot to mention how yellow lights are shortened at intersections that have the red-light money-maker screw-U-citizen-because-we-want-your-money-ha-ha cameras.
- ptrcd003, on 10/12/2007, -0/+29All of you complaining about the sensor, be thankful you don't ride a motorcycle. I literally have to get off and walk to the sidewalk to hit the button.
- wadem, on 10/12/2007, -0/+26You have a favourite traffic light experience? Okay....moving along....
- hazlett, on 10/12/2007, -8/+26Exactly how I thought ! Who didn't know this ???
Bury it.......before it grows - devindotcom, on 10/12/2007, -3/+21But - that's exactly how I thought they worked!
I like these lights, though... sometimes. You know what I'm talking about. - ScionX, on 10/12/2007, -2/+19Makes me remember all the late nights out where my friends would take turns running over into the intersections to trigger them to change lights.
**** I feel old now. - silverbax, on 10/12/2007, -2/+18Yeah, that's how I thought they worked too. I was thinking it would be something completely unexpected from the headline.
- cazabam, on 10/12/2007, -0/+15I've never yet figured out why some people insist on stopping 20 feet behind the line at lights. Do they think they need a run up to get past when it goes to flashing amber?
- leobaby, on 10/12/2007, -3/+18I think these sensors sometimes create congestion. I'm sitting at a red light forever, the next light, times out waiting with no one there, turns red just in time for me to get to the sensor. Freaking great.
- foolonthehill, on 10/12/2007, -0/+14My all-time number one traffic light experience was when I was at a crossroads and they turned green both ways. Fortunately it was a Sunday morning and there wasn't much traffic about, but still enough to have several cars coming in each direction and cause a lot of confusion.
- Thater, on 10/12/2007, -2/+15I've had experiences in my hometown with one particular left turn traffic light that's very particular about the exact location of your vehicle. One night I sat at the light through 3 rotations (where the intersecting streets both went through their red/green) without it recognizing my presence. Eventually traffic cleared up and I just went.
- osbjmg, on 10/12/2007, -3/+16It's better than a timer-based system. They still have that in my city and it ends up that there are like 10 people waiting on either side of the street for 2 minutes and then one lone car goes rolling by. Really frustrating.
Why does this article say "now how you would think?" This may not be common knowledge, but I sure knew about it - I didn't think it was magic. What else would the wires in each lane be for possibly? You could just guess it if you didn't know. It is an okay article, I read it, but no diggy. - BIGmog, on 10/12/2007, -1/+13In some states, it's legal for a motorcycle to run a red light on the excuse that the light was never going to change.
- DocDEB, on 10/12/2007, -0/+12Actually it is a sophisticated pattern recognition program built into every traffic light system that recognizes me and always turns red whenever I approach an intersection. So if you are following me be prepared to stop.
- PantherX, on 10/12/2007, -3/+15I knew how they worked, I'm just surprised that nobody else did/does.
I guess I wouldn't have to yell "MOVE UP TO THE DAMN SENSOR" all the time if people had a clue. - marillion, on 10/12/2007, -10/+22I've known this for twenty years. No digg.
- airship, on 10/12/2007, -0/+10Man, they're right. That's not how I thought they worked. I thought there was a midget in that big yellow box.
Now I feel foolish for shoving sticks of gum through the little slots for them. - foolonthehill, on 10/12/2007, -3/+12Seems people are digging ScionX down, but he's not talking crap (assuming he really is old enough). Before using inductors like these, some traffic lights use to have pressure sensitive strips to detect cars. You still see them occasionally these days, in temporary traffic-monitoring set-ups. They're designed to take something at least as heavy as a motorbike to trigger them, but if you really stomp on the things a human being can manage it too. I've been told it was a pretty common thing for drunken twenty year olds to do, in addtion to the timeless activity of stealing signs and traffic cones.
- inactive, on 10/12/2007, -0/+7That's just inept design. Properly designed traffic systems will tend to give you mostly green lights - that's what UTC (Urban Traffic Control) is about.
The article misses out the other two significant forms of vehicle detection - MVD (Microwave Vehicle Detector) and IRD (Infra Red Detector). MVDs can only look at moving traffic (they rely on the Doppler effect), so in a good design, they will be augmented with IRDs "looking" at the stop lines.
These "overhead" detectors are becoming ever more popular, because they don't require the capital expense of slot-cutting the road surface, and running loop feeders. However, their detection accuracy is poor compared to inductive loops, and they can't reliably discriminate between parallel lanes of traffic. - cazabam, on 10/12/2007, -1/+8Near where I used to work there is a little used industrial entrance with an inductor-triggered traffic light on it. I noticed while I was getting in my car in the pub carpark next to it that a guy on a bike had been waiting for ages, getting increasingly frustrated. I took my car out, parked it next to him in front of the light, and it changed within a few seconds. He was most relieved :)
- Snakedal337, on 10/12/2007, -8/+14I figured it was aswell, since it tends not to change for motorcyclists
- Kennils, on 10/12/2007, -13/+19This is really interesting. I always thought that the cut in the asphault was to permit some sort of scale system. I had no idea it was really the principle of induction.
- bitswapper, on 10/12/2007, -4/+10FTA: "There is something exotic about the traffic lights that "know" you are there -- the instant you pull up, they change!"
WTF? The instant I pull up? What kind of drugs are they on? - sirket, on 10/12/2007, -4/+10Mark1373:
So I guess you haven't heard about the cases of cops intentionally changing the light to red to try to catch people (This happened in the Bronx just outside the zoo where a cop was intentionally roling over a street sensor that immediately changed the light to red and caught people completely off-guard just so he could give them tickets)? Or jurisdictions intentionally shortening the yellow light at a camera intersection to try to catch more people?
A light is supposed to remain yellow 1 second for every ten miles an hour of the posted speed limit. If the speed limit on the road is 50 miles per hour- the light should remain yellow for 5 seconds. 30 MPH it should remain yellow for 3 seconds. Setting up a camera at a light on a 30 MPH road and then intentionally shortening the yellow light to 2 seconds (or even 1 in some extreme circumstances) is dangerous and downright criminal.
Countless studies have shown that if the goal is simply to stop accidents then increasing the yellow duration and increasing the red light overlap will dramatically reduce accidents. Adding a camera will not significantly reduce t-bone accidents but will dramatically increase rear-end collisions that occur because people brake hard to avoid getting a ticket. Moreover, a camera does nothing to stop a drunk driver after he has just blown through it. So he gets a ticket a week later? No cop was there to pull him over and arrest him for DWI.
To summarize- camera's at intersections perform a great service- they increase accidents but at least they generate money for the company that maintains them- and a little for the city too. - felchdonkey, on 10/12/2007, -1/+6Just curious - what's your all-time number fourteen traffic light experience?
- EnviroChem, on 05/22/2009, -0/+5If people think these lights are bad with aluminum bicycles, they should try them with carbon bikes.
One trick that does have a good success rate for me is to roll the bikes on the groves and bounce up and down a little. Using this trick I can oftentimes even get the sensors to give me a light on my carbon fiber bike. I bet this trick works even better with motorcycles and scooters. - kf6zql, on 10/12/2007, -0/+5Hahaha... that's funny, 3 weeks ago I wouldn't have gotten that. For those in the US, in europe (at least germany, uk, france) the lights don't go from red to green immediately, they go from red to red/yellow to green.
- eddiebabie, on 10/12/2007, -0/+5The same system is used in car parks to ensure that the barrier comes down after you've passed it rather the denting the roof of your car :)
- elguando, on 10/12/2007, -1/+6I used to live in a town with a lot of Mennonites. Their horse buggies weren't able to set off the traffic light signals, so they were told to wrap a copper wire around their buggy. It's a good thing too because there's nothing like being stuck at a light behind a horse taking a crap.
- ElectricGrandpa, on 10/12/2007, -1/+5Obviously everyone doesn't know about this since there are over 1500 diggs on it.
- inkswamp, on 10/12/2007, -0/+4> One night I sat at the light through 3 rotations (where the
> intersecting streets both went through their red/green)
> without it recognizing my presence.
A few years ago, my wife and I were sitting about 5 cars back at an intersection that was doing this. Nobody was moving, there was no cross-traffic and it was clear the light wasn't going to turn. We were literally sitting there for several minutes. Eventually, I noticed that the front car was way over to the left side of the lane in such a way that it probably hadn't triggered the sensor. There was enough room on the shoulder for me to go out and creep ahead of everyone and trigger it myself. So I did it. About 10 seconds after that, the lights flipped. As the traffic started moving, I thought I had done everyone a favor. But of course, everyone behind me drove by flipping me off and shouting things out their window because they thought I was being an ass trying to sneak ahead, despite the fact that I wasn't trying to get back into the traffic.
*Sigh*... the joys of being a little more attentive than the average driver. :^/ - JimMarchwBBV, on 10/12/2007, -1/+5Motorcyclists sometimes zip-tie big magnets to their kickstands and set those right on top of the wire. Otherwise we get screwed a lot...'specially if we have aluminum rims and frame, magnesium crank/tranny case, basically less real steel overall than a bicycle...
- TGKnIght, on 10/12/2007, -0/+3What does this mean "Not how you would think!"
WTF kinda way did you think it happened before you read this? Traffic-Light Monkey??? - inactive, on 10/12/2007, -0/+3If a bicycle won't be detected, the sensors are set up wrong. I can trip the ones here in the UK with the tip of a steel-toecap workboot.
Here in the UK, we typically have three sensors on each traffic approach - to place a demand for that approach, then to extend the green period when that stream of traffic moves off. A traffic controller is programmed with minimum phase times (typically 7 seconds), maximum phase times, phase extensions (times added for each vehicle over a sensor), intergreen times (safety clearance period to allow the junction to clear when lights go Red), and many other parameters (we even alter the timings by time of day, in order to optimise traffic flow!).
The police have no authority (and no ability) to alter the settings of a traffic controller - indeed ANYONE (Police or not) tampering with traffic signal equipment without authority in this country is liable to 7 years in prison! - cornerback42, on 10/12/2007, -0/+3Here's some other interesting things I know about this, I worked in a traffic division for a city for about 2 years. When the loop isn't working (you'll know by the unnecessarily long wait) it usually defaults to a set time of when to let people go this can be extremely annoying. Usually a letter to the city department can get them to get a company to come out and fix the loop. Also depending on the traffic system used alot of people don't know that they are controlled by a dial up connection that can watch the lights in a given city in real time. And my last bit of info is that if any 2 light bulbs burn out or go out in an intersection (the walk, don't walk lights or any of the traffic lights) the computer automatically defaults into the flashing yellow and red lights. Ours was programmed like that so when bulbs burned out we knew its probably not safe having 2 or more bulbs burned out so it seems like a reasonable safety check. I'm wondering if this is like this everywhere. Anyways that's all I have feel free to comment.
- enkoopa, on 10/12/2007, -0/+3If you're on a motorbike/bicycle, the most sensitive place to park is with your wheels on actual cut in the pavement, directly over the wire, not in the middle of the "box".
In Ontario, we have 3 yellow dots painted on the street at traffic lights where bicycles are supposed to stop, this indicates the most sensitive spot of the inductor. (It's usually at the front right cutout mark 99% of the time). - DoctorLex, on 10/12/2007, -0/+3Indeed, on my way home I have to pass 2 of these sensors. I mostly drive home on pretty late hours, so there are almost never any cars. The second sensor appears to be sensitive enough to detect my bike, but the first one is a real pain, especially because the crossing is too dangerous to just ignore the red light. I wonder if it wouldn't be possible to use an electromagnet to generate a fake signal in the coil. This would be somewhat more practical than BlackLineFish's solution :) However, the thing would probably need to be large and unwieldly as well.
- chkltcow, on 10/12/2007, -4/+7Not enough metal in a motorcycle frame for induction to work right, from what I've heard. That's why sport bikes get stuck waiting, and big slow cruisers trip the light.
- dattaway, on 10/12/2007, -0/+3No one in the motorcycle community has been able to prove magnets work. I have a large version of one and it still has no effect.
- carlosauresrex, on 10/12/2007, -0/+2no, it doesn't, once the inductive loop is triggered it's a matter of waiting no matter how big your car is.
- razorpit, on 10/12/2007, -0/+2Happens to me all the time when I'm on my motorcycle! I can't trigger the light and the people behind me won't help.
- Otto, on 10/12/2007, -0/+2>>>"Induction works great for cars, trucks, buses, etc, but can be a real pain for bicycles. I know of people who have to lay their bike down on the asphalt to trigger the light change. If you're on an aluminium framed bike, forget it!"
Get a flat, but medium to biggish size neodymium magnet, and attach it underneath your bike somewhere. Problem solved. You'll trigger the loop every time.
They sell devices specifically for this problem, but this is the basic principle behind them all. Just look for a supplier of large magnets and find one that will fit under your bike and not be too obtrusive.
Some people have been known to attach these magnets to their riding boots/shoes. When you stop at the intersection, drop your feet to the ground, and you can trigger it that way too. - jokeyjon, on 10/12/2007, -2/+4Induction works great for cars, trucks, buses, etc, but can be a real pain for bicycles. I know of people who have to lay their bike down on the asphalt to trigger the light change. If you're on an aluminium framed bike, forget it!
- Ryosen, on 10/12/2007, -0/+2Wow. Dugg down for a Monty Python reference. And you call yourselves "geeks"? For shame!
- databasecowboy, on 10/12/2007, -0/+2All you have to do is ride your bike on that seam and stop on a seam. The weight of you and your bike will trigger the lights 99% of the time. Even a fancy carbon fiber bike.
- OrangeTide, on 10/12/2007, -0/+2I hate these things when I'm on a motorcycle. Maybe 1 in 4 will change for me. If you're on a bicycle then you best get ready to just run a lot of red lights.
There are some opticals ones (works kind of like those motion sensor lights people setup in their yards). The ones with sensors under the road are pretty annoying though, those are by far the most common kind. Which is sad since the optical ones are much cheaper and don't require modification of the road, though they have a lot of (harmless) false triggering. So what if the light changes a few times more often than it ought to. It's far better than not often enough. - racazip, on 10/12/2007, -1/+3Yeah, I used to ride a scooter, and it was a real pain getting around late at night (when no other cars could trip the sensor for you). And don't get me started on drive-throughs... so many bad experiences... they usually ended in tears.
- felchdonkey, on 10/12/2007, -2/+4Anyone who has taken 6th grade English would know where the comma belongs in your sentence. But, hey, it's fun to call people ignorant, isn't it?
- reiggin, on 10/12/2007, -0/+2I just want to see a picture of one being installed.
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