It’s like one of the world’s greatest wonders (at least to me!): how traffic lights work. So in this installment of “I’m Curious…” I decided to figure out if moving forward, or backwards a bit is actually going to trigger that light, or if I’m just wasting my time?
So here’s the deal: every traffic light has some sort of timer or sensor, depending on the regular traffic flow at that intersection. In most busy, metropolitan areas, stoplights are on a timer, with by time of day, or statistically regulated flow, but in suburban and rural areas, the flow of traffic is more important than the volume. Here, sensors could be anything from a laser (beam me up Scotty), to a rubber hose filled with air (watch where you point that thing!). But by far the most common detector, is the induction loop. Basically, it’s a coil imbedded in the road’s surface. If you’re driving and see a big rectangular loop cut into the road, seal with a compound, that’s your induction loop. This website has a great and elaborately detailed system of how to trigger the different induction, or Demand Actuated, loops out there.
Bottom line is: if you see a rectangular shape just before the stoplight then you have a chance to trigger the induction loop. If not, you’re at the mercy of the road engineers. Yellow means go, but very slow!