Traffic Lights

The ubiquitous traffic light. Synonymous with cars. With over half the human population living in cities, traffic lights have become part of life. We allow them to tell us when to start, when to stop and when things are to change. Without them, chaos would permeate the transportation industry and bring grid-lock to every city dweller. So, yes, we need these red, yellow and green lights to control our lives.

Traffic lights are simple. Yet telling. A tall post keeps the lights above traffic. Wires in the post provide the lights with electricity. And control wires in the post may influence the light’s activation. Yes, simple. Telling is that their installation can cost $2million for one intersection. Typical incandescent lights use 2.4 kilowatt hours a day. Never stopping. The city of Toronto has 2346 lights. Suggestions are that the USA has over 300,000 lights. Would a global count of one million be reasonable? That’s 3.2E15 Joules/yr of energy to keep them turning on and off for every moment of every day.

And if you’re in a car waiting at the lights, your car is idling. Burning petrol to no avail. Say on average there are two cars waiting at every stop light. Every day. That’s 1.2E18 J/yr. A huge amount just to keep order within our transportation industry. Which doesn’t take into account energy lost in braking the cars and accelerating the cars. Cars and traffic lights make for quite a combination in terms of energy consumption.

Are traffic lights relevant? They don’t use a lot of energy Are they symptomatic? Their effect, cars waiting at lights, has a high energy usage. And traffic lights are essential for our transportation industry. So we will keep using traffic lights. And cars. But, for how long? Until all the gasoline is spent? Is this the best way to use the finite resource of utile energy stores on Earth? Blinking on and off.