When we travel a street and are stopped by a traffic signal, or we see a traffic signal change from red to green as we approach an intersection, we do not immediately think of a computer. If we are traveling in most modern cities throughout the world, that is what gives us the red or green light. Computer technology has become a very vital part of the Traffic Engineering field. Computers are at work in all aspects of this engineering specialty.
The Stop and go at intersections is detected by a camera mounted on an arm or span wire extended out across the intersection in the directions to be controlled. The cameras are connected to a computer located in a cabinet, located strategically in the intersection. The cameras are situated to pick up an area of viewing that alerts the computer when a vehicle is in that zone. The computer can be set on what is referred to as recall, in which it will alot equal time to traffic in each direction of the intersection. In addition it also can be programmed to give an exclusive green light to which ever lane of traffic is preferred, such as a left turn lane.
There are also computers with camera connections that monitor traffic flow at primary intersections on city streets.
These computers and cameras are tied to a monitor in a Traffic Management Center located somewhere in the city. These centers have technicians that view traffic on the monitor, with the technicians having the ability to change the timing on the traffic lights allowing traffic to have a longer green light in the desired direction. This type of technology is advancing at a rapid rate.