Bananation: The Traffic Signal

A clear beacon of our increasingly motorized society is the humble traffic light or traffic control signal. It has spread across our cities silently but pervasively and now stands on most major roads that do not have the "freeway" classification (might be motorway or expressway in your jurisdiction and but anyway it is seldom free).

Let me tell you a little about traffic lights. Physically they are the visible part of a computer based system which has been pre-programmed to respond in particular ways to electronic signals received. As a road user we see the response as a red or green or other type of signal to which we are expected to act in a certain way. The programming is all done prior to you arriving at a traffic light intersection. This is the first and most important thing to understand. You can shout, tap your fingers, cuss or just feel high levels of frustration but these will not change the program; they may, however, relieve some tension and give you a sense of relief as you wait for the go command (or green light).

The signals received by the computer can be generated by a vehicle detection and/or monitoring device, by someone pushing a pedestrian button or maybe from a clock which triggers a set pattern of red/green/warning signals for a set period of the day. As a result of these signals, a pre-determined response will be triggered in the computer and the signals will reflect that response. There are many permutations but remember the computer has no eyes and hence it will always go through the particular sequences programmed. Typically if the light is to change then it will allow a clearance phase (usually an amber signal) before responding to the signal (from a motorist point of view it is a request) to change to a green signal. These onset of the clearance phases can be delayed in starting by such things as high priority roads (eg off ramps from Freeways), crossing times for pedestrians (based on an average or slower walking speed) or the linkage of computers operating at several intersections.

The computer system may control an isolated intersection, a series of intersections or an entire network and is programmed to maximize traffic efficiency without compromising safety. This programming is done by highly skilled persons to well established guidelines and in compliance with the prevailing traffic law. For instance it is poor programming to have a pedestrian crossing phase following the highest speed movement at the intersection because potentially there are more vehicles coming through the signals late and the drivers have less time to react because of the higher speed or clearance times are adjusted to match the approach speed, that is longer clearance times for higher speeds.

I provide this basic outline of a traffic signal to increase people’s understanding as a means of reducing the visible frustration and annoyance seen at traffic signals. There are some basic things to remember at traffic signals:

They cannot see and hence no finger signs or waving of fists has any effect on how long you wait. For instance the computer does not know that the vehicle who was detected approaching the signal on road A did in fact go through the red light and is no longer there so there will be a green light response for that vehicle.

The signals received are recorded and entered into the system for analysis against pre-programmed responses. Creeping over the white line does not get you a quicker green light only angry looks from pedestrians as you steal their space. In fact the detectors that identify to the system a vehicle has arrived are usually set back from the white line.

The red light camera does not lie. The detection equipment for these cameras is located usually 1metre or more past the white line.

Pedestrian and cyclists do have to obey the signals given. Real life observations may cause you to doubt it but it is the law.

So when you are next stopped at a traffic signal just accept that this a computer generated response to information received and while the information maybe faulty the computer is just responding in a pre-programmed manner. So relax and enjoy the beautiful things the world has to offer and arrive at your destination not only safely but feeling great.