I read in a post here that some people just got their license, so I thought I'd pass on this pretty neat trick. You see that picture? That's not some road patch work, no sir. That there is a metal detector. Now, I haven't done a whole lot of driving outside of Ohio, but we have these all over the place. What they do is detect distortions in a magnetic field caused by a vehicle over top of them. Each trigger can cause different events, but certain detectors in certain places can be taken advantage of. Some of them just measure traffic flow or count to control the timing of lights in busy intersections. More cars mean a different light pattern to maximize flow for certain times of day (rush hour, etc). Not much you can do, as they are usually several hundred feet from the intersection and you just pass over them. But some are located in left turn only lanes. These are my favorite. You see, they can be positioned about three to four car lengths back and the [i]theory[/i] is that, if you have several cars stacking up to turn left, one of the back ones will be parked over top of it and cause a left green arrow for your lane, allowing you to bypass the pesky and often useless simple green light where you'd have to wait for a break in on coming traffic. HOWEVER, this only detects when there's a car above it and pays no mind to if there's actually a line of cars. There's one of these in a particularly congested intersection I find myself in frequently. The trick I've used is to just park your engine right above it (with all the plastic in cars, the engine is the safest bet to ensuring the sensor is triggered. True story.) Even with no cars but me in the turn lane, I will consistently trigger the left green arrow. Pretty handy. These can also be found at intersections where a less busy road intersects a major traffic way. They can tell the traffic control system that someone is waiting to cross or merge into the heavy traffic area and to give them a green light soon. The purpose here is to interrupt the heavy traffic as least often as possible. No trick here, other than to be sure your engine is stopped over top of them to minimize waiting times. Lastly, if you know your vehicle is quite poor at activating them, you can attach a hefty magnet or two in and around the largest pieces of metal you have on your car. This is particularly useful for motorcycles and other small modes of transit. This will ensure that there is enough of a distortion in the magnetic field to trigger the sensor. Well, that's all I've got for you. Keep an eye out for such things or other means of vehicle detection. Let me know if you want more.