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canopuss
2010-Sep-19, 09:28 PM
Could there be some sort of vehicle sensors fixed near traffic lights so that on less-busy roads (minor roads) lights turn green only when there is a vehicle there to turn into busy roads (major roads), thus avoiding unnecessary traffic delays on busy roads ?

pzkpfw
2010-Sep-19, 09:32 PM
We already have something like those here, and I'd expect in many places.

(Sometimes one can see the rectangle cut into the road surface where the detector loop has been placed.)

It can cause issues for small motorcycles, where they don't trigger the sensor and the sequence never lets them in.

I've seen riders write of hopping off their bike, popping over to push the pedestrian crossing button, to get the cycles to change.

Nick Theodorakis
2010-Sep-19, 09:42 PM
That's they way it works around here. Most if the ones around here seem to be triggered by some kind of camera-looking device atop the traffic light pole, but I don't know what kind of sensor it has. The only downside is it seems to misfunction in heavy fog.

Nick

kleindoofy
2010-Sep-19, 09:49 PM
We've had that here for well over twenty years.

Gillianren
2010-Sep-19, 10:02 PM
I don't know how long they've had them in Olympia, because I've only lived here for ten years. And, yes, my friend who drives basically a scooter has a real problem with them and has made illegal left turns onto our street because it's midnight and no one else is anywhere near the light.

slang
2010-Sep-19, 10:33 PM
A few years ago the local bus company posted an ad in a local newspaper, stating that residents could come to their main office, and buy for a very low price the (depreciated) devices that city buses use to get preferential treatment by traffic lights. Many people showed up. Equally many people discovered at that embarrassing moment that it was April 1st. Many more people laughed.

kleindoofy
2010-Sep-19, 10:41 PM
... buy for a very low price the (depreciated) devices that city buses use to get preferential treatment by traffic lights. ...
And what were you expecting one to cost when you got there? ;)

Swift
2010-Sep-19, 10:50 PM
That's they way it works around here. Most if the ones around here seem to be triggered by some kind of camera-looking device atop the traffic light pole, but I don't know what kind of sensor it has. The only downside is it seems to misfunction in heavy fog.

Nick
IIRC, there are two types of technologies: the optical systems Nick talks about, and the inductive loops that pzkpfw talks about, each with their pros and cons.

JustAFriend
2010-Sep-20, 12:13 AM
Google is your friend: http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/question234.htm

Jens
2010-Sep-20, 05:39 AM
A few years ago the local bus company posted an ad in a local newspaper, stating that residents could come to their main office, and buy for a very low price the (depreciated) devices that city buses use to get preferential treatment by traffic lights. Many people showed up. Equally many people discovered at that embarrassing moment that it was April 1st.

Is that really OK to do? It sounds like a lot of people wasted gas and time because of the hoax. I'm surprised that nobody sued them for false advertising. I mean, it's funny, but somehow you have to weigh that against the trouble that you cause.

HenrikOlsen
2010-Sep-20, 09:59 AM
Slang's in the Netherlands, not the US.
People don't sue others when they themselves have been stupid.

kleindoofy
2010-Sep-20, 10:22 AM
Yup, large scale April Fools jokes are traditional here, just like the one slang mentioned.

I'll never forget the one a few years ago when the 12.00 news reported that Napoleon was reorganizing his troops ...

Strange
2010-Sep-20, 10:36 AM
IIRC, there are two types of technologies: the optical systems Nick talks about, and the inductive loops that pzkpfw talks about, each with their pros and cons.

Round here we have some junctions with a mixture: inductive sensors on one route and "optical" (I am guessing doppler radar?) motion sensors on the other. Off the top of my head, I think it is the major road that has the motion sensors - perhaps so it can detect cars at a distance and switch back to green before they get to the the junction.

Jens
2010-Sep-20, 03:36 PM
Slang's in the Netherlands, not the US.
People don't sue others when they themselves have been stupid.

Well, Ok, but somehow you have to have limits. Suppose you made a practical joke, and told people there was a pot of gold on the other side of the bridge, but in fact the bridge didn't exist and a number of people drove their cars off the bridge and died in the river. I assume that police would not think it was that funny, whether the people had been duped or not. Surely there has to be a limit on how much damage you can cause to other people, even due to their own stupidity.

Ara Pacis
2010-Sep-20, 05:10 PM
Well, Ok, but somehow you have to have limits. Suppose you made a practical joke, and told people there was a pot of gold on the other side of the bridge, but in fact the bridge didn't exist and a number of people drove their cars off the bridge and died in the river. I assume that police would not think it was that funny, whether the people had been duped or not. Surely there has to be a limit on how much damage you can cause to other people, even due to their own stupidity. How could people drive off a bridge if it doesn't exist?

NEOWatcher
2010-Sep-20, 05:13 PM
There's also several intersections around here that have multiple sensor loops. They detect the volume of traffic so the light can be made longer if necessary. (usually for left turn lanes)


... the (depreciated) devices that city buses use to get preferential treatment by traffic lights...
I drove buses equipped like that in college. Supposedly it was a groundbreaking research system before they went into commercial use (unfortunatly, I can't find references to support that).
By the time I drove, the only functional part of the system left was the one where a bus would trip a timer that told the next bus when to depart on a single route.

slang
2010-Sep-20, 05:45 PM
BTW, we have the induction loop thingies here, just to stay on topic :)


Is that really OK to do?

Yes. Trying to get a group of people to show up for some (blatantly obvious) non-event is a common April Fools joke type here.


It sounds like a lot of people wasted gas and time because of the hoax.

I don't remember exactly. Tens, not hundreds. Which is a big turnout for such a joke.


I'm surprised that nobody sued them for false advertising.

Sueing for an April Fools joke? That would have been even funnier than the joke itself and the entire country would have been in stitches, laughing at the northerner nitwit who'd try that.


I mean, it's funny, but somehow you have to weigh that against the trouble that you cause.

And what makes you conclude that negative consequences were not considered beforehand, and discussed among the bus company and the newspaper that posted it? Possibly the police were notified, in case of traffic problems, but probably not. They read the paper too. For goodness sake, how many people are dumb enough to come get an egoistic magic box to mess up the traffic light cycles in an entire city, on April first!?

They wasted an hour of their day, and probably got a free cup of coffee, and most got a good laugh. So what. It's not like they jokingly reported that swallowing paint thinner was discovered to grow bigger [insert applicable bodypart here] ...

slang
2010-Sep-20, 06:05 PM
I drove buses equipped like that in college. Supposedly it was a groundbreaking research system before they went into commercial use (unfortunatly, I can't find references to support that).

Yeah, it's a major research topic. Especially with the congested cities here, with narrow roads. Ain't much use to have a public transportation system if it's just as bogged down as other traffic. Well, it would serve some people, but it would fail at the intention to keep other traffic out of the cities.


By the time I drove, the only functional part of the system left was the one where a bus would trip a timer that told the next bus when to depart on a single route.

All this box does (or did, this was at least 10 years ago) is alert the traffic lights that a bus is approaching, and that as soon as possible that lane should get a green light. I'm sure the computer operating the lights knows better than to keep only that one lane on green. Probably different operating patterns, just like how some lights behave different during morning and evening traffic peaks.

Trebuchet
2010-Sep-20, 06:23 PM
We've had induction loops here for a very long time. And as others have said, it's a problem for lighter vehicles, like the 1974 Honda Civic I once had. On solution would be to have a maximum time after which it changes regardless.

The optical sensors around here are, I think, only used to change the light for emergency vehicles, which have a white strobe they turn on when in emergency mode.

Jim
2010-Sep-20, 06:44 PM
I'll never forget the one a few years ago when the 12.00 news reported that Napoleon was reorganizing his troops ...

They went Union?

captain swoop
2010-Sep-20, 08:29 PM
Yup, large scale April Fools jokes are traditional here, just like the one slang mentioned.

I'll never forget the one a few years ago when the 12.00 news reported that Napoleon was reorganizing his troops ...

Taht wasn't an April Fool, you just live in an out of the way place .

slang
2010-Sep-20, 09:22 PM
Taht wasn't an April Fool, you just live in an out of the way place .

Karma, kleindoofy! This is post #7 hitting back :D

tlbs101
2010-Sep-21, 11:24 PM
Could there be some sort of vehicle sensors fixed near traffic lights so that on less-busy roads (minor roads) lights turn green only when there is a vehicle there to turn into busy roads (major roads), thus avoiding unnecessary traffic delays on busy roads ?

There are several of these types of crossings near my home. In order for me to turn from my local arterial street onto a 4-lane divided state highway (50 mph), I must wait for a traffic sensor (inductive loop type embedded in the asphalt). For some reason the traffic engineers decided that if demand was only from one direction, only that direction would get a green light. Several times I have made it to the intersection just as the light changed green for cars on the other side, coming toward me, but too late for my own sensor to change my signal. I usually run the red light because I know it is safe (waiting for the cross traffic, of course).

Further down on this state highway is another demand-based traffic light for a residential district. I find that if I am on the major highway and have to stop at this intersection, that I lose synchronization with the traffic lights further up the highway (spaced every mile). On green, if I travel the speed limit then I will 'hit' 4 miles of red lights, one after another. If I speed up to 70 mph then I can barely make the next traffic signal (on the mile) just as it turns yellow.

Trebuchet
2010-Sep-22, 01:13 AM
The traffic lights on the main drag of the town where I attended college were times so that if you were eastbound, you basically stopped at every light. Conversely, westbound traffic generally didn't have to stop at all. The side streets got a lot of eastbound traffic as it was faster to stop at all the stop signs than all those lights.

At least we had left-turn lights, something my home town, the largest city in a small state, had not yet discovered.

Gillianren
2010-Sep-22, 03:24 AM
Across town from me, there's a shopping center with several major stores. There is also, in that parking lot, the Lacey theatre, which has 16 screens. The turn into the parking lot closest to the theatre sort of has a turn light but not really; you're supposed to yield to oncoming traffic. Since there is always oncoming traffic, I always just go down another block to where there is a turn light. I don't know what's wrong with everyone else.

korjik
2010-Sep-22, 04:15 AM
Across town from me, there's a shopping center with several major stores. There is also, in that parking lot, the Lacey theatre, which has 16 screens. The turn into the parking lot closest to the theatre sort of has a turn light but not really; you're supposed to yield to oncoming traffic. Since there is always oncoming traffic, I always just go down another block to where there is a turn light. I don't know what's wrong with everyone else.

I have been wondering that for decades

:)

Ara Pacis
2010-Sep-22, 04:24 AM
I have been wondering that for decades

:)

What's there to wonder?

Click Ticker
2010-Sep-22, 04:22 PM
We've got a main street in town that is timed so if you drive 55 (which is the speed limit), you will catch every light green. Works in both directions. They've got the timing down pretty good. It's always fun to watch someone in a big hurry trying to beat the lights only to pass them at every light because they had to come to complete stop and wait for green.

NEOWatcher
2010-Sep-22, 05:05 PM
Timing both ways is a very difficult task.
You wouldn't by any chance be talking about Telegraph road near Detroit would you?

It's the same as what you describe. It has the advantage of the intersections being fairly consistently spaced.

slang
2010-Sep-23, 08:31 PM
We've got a main street in town that is timed so if you drive 55 (which is the speed limit), you will catch every light green.

We have (or had) similar systems here. It was called (and indicated with a sign) "groene golf" ("green wave"). But it's been a while since I've seen those, presumably more intelligent controllers for traffic lights are more efficient.