When a vehicle on a side road arrives at the intersection, a sensor will detect it and cycle the lights to allow traffic on the side road to pass through. So how do sensor-based systems maximize traffic efficiency? In a rural area, for example, the main direction of travel can remain on green to allow the majority of vehicles to pass through quickly. The wire detects changes in magnetic fields when vehicles (large metal objects!) are stopped above them. ![]() These systems rely upon a coil of wire embedded in the road's surface. Some systems use lasers, rubber hoses filled with air, or video cameras to detect the presence of cars.Īnother popular type of sensor is known as an inductive loop system. The types of sensors used can vary by location and technology. Rather than timers, "smart" or "intelligent" sensor-based traffic signals rely upon a system of sensors to detect when vehicles are present. In these situations, sensor-based traffic signals maximize traffic efficiency by only functioning when traffic is present. For example, in a rural area, a timer-based system might have drivers stopped unnecessarily when no traffic is present. In areas where traffic can be sporadic and unpredictable, timer-based systems don't work as well. Timer-based systems are excellent for busy areas that have a consistent, heavy volume of traffic. Depending upon traffic levels at a particular intersection, the traffic light will cycle through green, yellow, and red at regular intervals to ensure a consistent flow of traffic in all directions through the intersection. The most common traffic lights work on simple timers. The red light, of course, indicates that drivers must stop and wait for a green light before traveling through the intersection.Īlthough most traffic lights have a similar appearance, they can often function in very different ways. When drivers encounter a yellow light, they know it's necessary to slow down and come to a stop at the intersection. A yellow light (also known as a caution light) alerts drivers to the fact the light is about to change to red. The green light signals that it's safe to proceed through the intersection. Without traffic lights and stop signs, navigating your way around a big city could be quite dangerous.Īs you probably already know, most traffic lights feature three colored lights. While traffic signals may be a mystery to dogs, human drivers are happy that they're there to regulate the flow of traffic on busy streets. ![]() Nevertheless, their brief conversation did make us WONDER about the traffic lights that hang above intersections. We're not sure if they ever caught the car or, if they did, what they would've done with it. Rex and Charlie took off in a flurry of fur and barking. Oh well, I need to get back home to chase cats and bark at leaves.ĭog 2: Look! That car is coming this way. It's like they've got all the time in the world and are never in a hurry.ĭog 1: People are so weird. Why would they do that? It's almost like they don't have anywhere important to be. That car was driving along and, even though there aren't any other cars around, it just stopped when that light up there turned from green to yellow and then red.ĭog 2: It's a mystery, Rex. Sit here and watch with me a while.ĭog 1: Would you look at that, Charlie? You're right. We were sitting at the Wonderopolis bus stop the other day when we overheard two dogs discussing the traffic at the nearby intersection:ĭog 1: So what you're telling me, Charlie, is that these humans drive these cars around and just stop for no reason simply because there's a red light hanging up in the air?ĭog 2: I know it sounds crazy, Rex, but I've watched the cars here for quite a while and that indeed appears to be what happens.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |