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LightAware 500
Cut down by seconds the hours you spend at lights each year. | |
Perhaps i have a solution to your problem...
let me introduce the LightAware 500.
I dislike waiting at traffic lights. If i could in any way cut down on the time i spend sat in them i would be incrementally happier.
30% of all waiting time at traffic lights is adducable to improperly
timed lights, where a line of traffic is kept waiting while an empty road sits smugly across a green light.
This is down from a peak of around 47% in the late 1980's The reason?, well in part it is due to the advances in the technology controlling the lights. One of the major factors has been the introduction of infra red sensors that detect which approaches to the junction have cars waiting or approaching.
The problem is that on very hot days the temperature of the road becomes about the same as the temperature of the hood of your car, which is what the IR sees; so you could be sitting waiting for minutes because the lights do not know that you are there.
The LightAware 500 would be a simple heating coil, mounted on the front bumper
niche marketing, perhaps, but i'm sure someone somewhere has experienced this problem.
(the figures are all attributable to recent estimates
Traffic Pre Emptive System
http://www.ci.linco...emesrvs/trfempt.htm
[phoenix, May 23 2002, last modified Oct 04 2004]
How Stuff Works: traffic lights
http://www.howstuff...com/question234.htm
Induction is the most common method for detecting cars. (Sadly some of the links on this page don't work.) [pottedstu, May 23 2002, last modified Oct 04 2004]
Above Ground Detectors
http://www.microsense.co.uk/above.htm
Both IR and microwave [stupop, May 23 2002, last modified Oct 04 2004]
AGD Systems
http://www.agd-syst...com/datasheets.html
A company that specialises in this type of detector. These datasheets give a comprehensive description of how each type of detector works. [stupop, May 23 2002, last modified Oct 04 2004]
DTLR Traffic advisory leaflet on the use of above ground detection systems
http://www.roads.dt...tm/tal/signs/16_99/
Quite a good explanation including discussion of the limitations of such detectors. [stupop, May 23 2002, last modified Oct 04 2004]
[link]
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I thought this was baked, in the form of an engine? ;op |
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I'd like just one reliable link referencing these 'infrared sensors'. Just one. |
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yeah, my understanding was that traffic lights used induction coils under the pavement (like an upside down metal detector) or even weight sensors. |
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The traffic sensors in my area are an upside-down "T" shaped device, with the arms of the "T" pointing up and down the street. Each intersection has two of them, one for North/South traffic and one for East/West traffic. No idea whether they work by induction or infrared, but I think they're too far from the street to work by induction. |
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[mwburden] I bet those are sensors for the emergency stobe lights they have on emergency vehicles. As the vehicle approaches the intersection, the sensor changes the light (if necessary) to give the vehicle the right-of-way and to let other traffic get out of its way. |
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There are sensors on the traffic lights at some intersections around here. They are attached to a sign that says something like "Vehicle detected". I'd guess they are sonar/ultrasonic or radar. They are sensitive enough to detect motorcycles (maybe even bicycles but I haven't tried). |
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In the summer in Phoenix, I think it would be tough to discriminate the infrared signature of a vehicle. You'd probably have to look for a cool spot in comparison to the asphalt. Infrared wouldn't be my first choice. |
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I could be wrong (again) but I suspect that the I-R sensors on traffic lights are active; they emit an I-R beam and detect a reflection, rather than passively detecting an existing I-R source, which is what domestic intruder alarms do. |
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I've never heard of IR being used for this purpose. I, like wiml, thought this was all controlled using induction coils. (Which, in my area, tend to be hexagonal - you can see the filled-in lines cut into the road surface at intersections where they've recently been installed.) |
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IR seems like a really bad way to do this. I can't believe it's used for this. Show some links, please. Otherwise, your idea is a non-invention. |
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I-R is used on temporary lights (at road works and such). I agree that permanent installations generally use induction loops. |
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Above ground detectors, both IR and microwave have been around and in use for quite a while. They are used to detect pedestrians, cyclists and vehicles (see links). |
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Thank you for the links [stupop]. Seems to be a U.K. phenomenon.... |
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[phoenix] That could be. Come to think of it, I'm betting on induction coils below the pavement for the sensors in our area. On 28th St., the left hand turn light won't go green unless there is actually a car in the left hand turn lane, and I can't see how else you could tell so precisely which lane the car was in. |
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[phoenix] If you remember your days in Metro Detroit, there are several 'burbs here that actually use full cameras to time the lights. |
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I don't recall, but that was 20 years ago for me. Lawd, I miss that place. |
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I wonder how high you have to mount an IR sensor to catch the heat from a mid-engine car? And most public buses use rear-mounted engines - I wonder how well those are detected.... |
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You can normally tell when there are induction loops in the road by a thin line of bitumen in a rectangle or diamond shape. There are a number of different types used for calling a demand, extending green time and for Urban Traffic Control systems. Most junctions in cities have all of these.
[mwburden] Above Ground Detectors can tell what lane a vehicle is in. |
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yeah, sorry about that everyone, i was ligging it just a little. cheers for the fish though. |
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Are you sure that they use heat, and don't just detect an interuption of the infra-red beam? |
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I heard that if you're a member of the
Stonecutters you get a special keyring
which changes all traffic lights to green. |
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perhaps an even more obvious IR beam, telling the
light it's time to move on. |
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