red light green light

You’re driving through a bustling city and to the astonishment of other drivers, every intersection displays a green light just before you reach it, allowing you to drive through in bliss. Sound too good to be true? It’s not. It could be you thanks to a new gadget that has traffic control officials worried. What if two people had one at the same intersection? Havoc and chaos would be wreaked in abundance, but man would it be convenient if you were the only one.

I was once told you could flash your brights at traffic lights, mimicking the flashing lights of a police car, to make the light turn green. I tried it several times and it never did anything so I’m inclined to believe they were pulling my leg.

Another way to get past a red light is the U-turn. When you see a red light, take a quick right, then do a U-turn and either go straight if you wanted to turn left, or take a right at the intersection if you wanted to go straight. Of course it only works if there isn’t much traffic, and that’s where that gadget would shine. It could be the middle of rush hour and it would still work, and at $300, it’s less expensive than the king of radar detectors, and ever so much more powerful.


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  1. I’ve never heard the flashing lights thing. That would be cool if it worked. As for the U-turn turn-right trick, it drives me crazy when I see people doing it, and I’ve seen people pulled over for it too. The other one is turning right at a light when that lane is totally full. Some people will cut through a business parking lot, usually a 7-11 and jump ahead of the people who are in the turning lane.

    Comment by jason on October 28, 2003 @ 8:05 am
  2. I think the flashing trick does work, but it depends on whether or not the lights are intelligent and at what hour of the day/night. Many lights in Provo are light detecting, and while I can’t give you a quantitative number of flashes needed or operation hours, I often flash my lights if no one is around. Depending on the light, and whether a default minimum time limit has been reached, it quickly changes to yellow. In fact the stoplight north of where we work, on the frontage road behaves that way too.

    Comment by Cameron on October 28, 2003 @ 8:49 am
  3. Police and ambulance services have those green light remotes here. Of course, very few municipalities have upgraded their traffic lights so that the police can actually use them.

    I’ve never heard of the flashing headlights at traffic lights before. If it’s not a hoax, then it’s not something that’s used in the southeast. Or at least, it’s not something included in the GDOT spec books for intersection lights. Around here, GDOT uses magnometers to sense when cars approach intersections. When the magnometers sense a car it sends a signal to a networked computer, which in turn signals the traffic lights to turn accordingly.

    If the municipality doesn’t want to pay for magnometers, the lights can be timed pretty effectively based on traffic studies of the intersection. You wouldn’t believe how accurate and efficient the timing sequences are if they’re done right.

    Comment by Jan on October 28, 2003 @ 11:32 am
  4. Jan: That’s interesting. How do the magnometers work? When I had my motorcycle I couldn’t get the lights to change until a car showed up, so I assumed it was due to weight.

    I don’t think Utah does their timing sequences right, because at two in the morning, you still have to wait for lights to change. Back in New Hampshire they would just turn the main road to a blinking yellow and the other way to a blinking red. It made life much easier.

    Comment by dan on October 28, 2003 @ 11:37 am
  5. I think you’re both correct. This document has all the specifications for optical intersection signals, including the magnetometer. I think it’s embedded in the pavement where the cars stop and maybe it detects the magnetic field of the car. With that it would make sense that your motorcycle wouldn’t be detected.
    Bangerter Highway’s intersections are definately not timed.

    Comment by jason on October 28, 2003 @ 2:14 pm
  6. I wonder if the optical sensors are sensitive enough to pick up a motorcycle. You’d think the engineers would take motorcycles into account during their design process.

    Comment by dan on October 28, 2003 @ 5:14 pm
  7. In Georgia, legislators are considering letting motorcycles turn left on red arrows, etc because the magnometers (that’s what GDOT calls them) don’t pick up motorcycles. The problem with motorcycles is that the magnometer equipment needed to ‘sense’ them is very expensive. Also, there’s a problem with pavement depth. Magnometers are under a couple of inches of pavement; This makes them less sensitive. In places where there’s a lot of snow and rain, they have to be buried even deeper.

    I hate to tell you this, but roads aren’t designed for motorcycles at all. They’re not designed for small cars, either. Roads are designed for medium sized trucks, which is the design vehicle size determined by AASHTO. Also, and this is something I’ve always thought was a little funny, roads are only designed so that 85% of people can drive them safely. That means that we design them so that 15% of the cars on them will have an accident.

    Comment by Jan on October 29, 2003 @ 5:27 am
  8. How rude of them, both for not designing for motorcycles, and for only having an 85% safety design. I’m not impressed.

    Comment by dan on October 29, 2003 @ 8:31 am
  9. I’m in the outcast 15% — not because I can’t drive them safely, but because many of the rules are ridiculously conservative. They weren’t designed for people who enjoy driving.

    Comment by Cameron on October 29, 2003 @ 9:04 am
  10. I’m curious about the 85% thing. What sort of vehicles fall in the 15%? If you remove traffic from the picture, small vehicles have a definite advantage over large ones when it comes to acceleration, braking, and corner grip, simply due to their lower mass. It seems to me that designing for larger vehicles then makes the road over-designed for small ones. Perhaps the 15% that aren’t safe are really huge trucks?

    Comment by Levi on October 29, 2003 @ 9:11 am
  11. The unlucky 15% is made up of different cars depending on the situation. Small cars and motorcycles (any car that has a low headlight) have a slight disadvantage in sag curves and have major problems with sight/obstruction. Huge trucks have a disadvantage in tight horizontal curves and crest curves.

    Motorcycles and small cars do have a driving advantage because of their lower centers of gravity; it’s one of the reasons why AASHTO designs for medium sized trucks instead of cars. Also, more and more people drive larger and larger vehicles. Last year AASHTO was considering raising the design headlight and sight height to match those of a mean SUV. Luckily that was rejected; it would have made some road elements very dangerous for small cars and motorcycles.

    Actually, the 85% is pretty good. If roads were designed for more, the streets would be ridiculously conservative, not to mention expensive. It would also lower speed limits dramatically. 85% is a good compromise, all in all.

    Comment by Jan on October 29, 2003 @ 10:25 am
  12. Yes, I am opposed to anything that lowers speed limits. I’m more for safer vehicles, safer drivers, and higher speed limits. It works in Germany, why not here? :)

    Comment by Levi on October 29, 2003 @ 2:12 pm
  13. Aye, Aye!

    Comment by Cameron on October 30, 2003 @ 8:25 am
  14. The sensor that determines if a vehicle is in a specific location is really a coil of wire. If you look at the road you’ll see cuts in the pavement (usually a rectangle) with a line going to the side of the road. Inside this cut is a loop of wire (usually looped 3-7 times) through which a current is sent. This creates a magnetic field that gets changed when a metallic object breaks the field. The sensor at the side of the road can be set to different sensitivities which is why some of them don’t pick up motorcycles.

    If you try breaking the field in different places it may help. I’ve found that the edge, directly over the wire, seems to be more sensitive, probably due to the shape of the magnetic field.

    Comment by Rick on October 30, 2003 @ 12:24 pm
  15. Rick: Thanks for the explanation. Now I need to get another motorcycle to test with.

    Comment by dan on October 30, 2003 @ 2:12 pm
  16. Good rationale. :)

    Comment by Rick on November 4, 2003 @ 11:57 am
  17. where can i get the green light gizmo?

    Comment by o on February 24, 2004 @ 12:17 am
  18. [email protected] thats where i can be reached if any1 knows the site or how i can get my hands on the gadget.

    Comment by Anonymous on February 24, 2004 @ 12:18 am
  19. Hey, all you need is a magnet attached to the bottom of your bike to make the loop detectors work. Search online for ferrite magnets they should be a couple bucks.

    Comment by friend on March 30, 2004 @ 2:14 pm

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