Someone asked me this the other day, so I’ll share my answer as it involves some pretty impressive figures.
London has over 5000 traffic intersections, each one comprising an average of 10 traffic signals, making about 50,000 signals. If those were to be converted to LED lights, the resulting saving in electricity alone (assuming a cost of 6 p per unit) turns out to be almost £1 million a year, with an annual reduction in carbon emissions of more than 9500 tonnes.
Presently, light bulbs in conventional traffic lights are changed every year, so as LEDs can be expected to last up to 10 years they would avoid up to 8 maintenance visits over their lifetime. That’s a lot of cherrypickers out of work.
If you want all the technical details, someone’s explained it here which saves me the trouble.
Now just think how many traffic hold ups you could miss if all traffic lights were LED.
Of course, you could save even more energy, cut more carbon and reduce driver frustration too if you follow this example and just remove traffic lights altogether.
Ealing Council says “How many times have we waited at a junction and nothing is happening? No cars are moving, no pedestrians are crossing. Nothing. Just wasted time, adding to our frustrations. So we will bag over some traffic lights and allow motorists and pedestrians to trust each other.” How refreshing!