3 August: Traffic lights

On this date in 1926 Britain’s first electric traffic lights were installed at Piccadilly Circus. Here are ten things you may not know about traffic lights:

1. It wasn't the first one in the world, though. The first electric traffic light was installed in Cleveland, Ohio on August 5, 1914.
2. The first traffic lights were manually operated, meaning a policeman had to stand there and change the lights. Before electricity traffic lights were manually operated gas lamps. There were some installed outside the Houses of Parliament in 1868. Within a month, they'd exploded. The danger to policemen meant they never really caught on.
3. In 1928, Charles Adler Jr invented traffic lights that could be activated by drivers honking. They didn't catch on either, due to complaints from local residents about the noise.
4. The first automatic traffic lights were installed in Wolverhampton in 1927.
5. The city in the UK that is thought to have the most traffic lights is Leicester.
6. The colours, red, amber and Green, were chosen because they were already in use on the railways. The reasons the railways chose them are lost in obscurity, but scientists know today that the colour red has a longer wavelength than green, and can be seen from farther away. This makes sense as it would give drivers more time to slow down.
7. Early traffic lights only had red and green lights, but lights changing from green to red with no warning led to accidents. In 1920, a Detroit police officer named William Potts added the Yellow (or amber) signal to warn drivers.
8. The oldest traffic light in the world still in use is in Ashville, Ohio. It was installed in 1932, and has the added distinction of an unusual design. It looks like an Art Deco-era rocket ship rather than a rectangular box.
9. Traffic lights are generally arranged with the lights above one another, but in some parts of North America they are arranged horizontally, sometimes with lights being different shapes as well as colours, because the horizontal arrangement is less vulnerable to storms and hurricanes.
10. Is it permissible to drive through a red light if the lights are broken and stuck on red? Actually, no - if the lights are broken then by law you should wait until a policeman or traffic warden comes to direct the traffic. There are tales, possibly urban myths, of people who sat at a broken red light for days until they nearly died of dehydration and everybody would say people who do that are somewhat lacking in brain cells - however, if you drive through a broken red light and are prosecuted you'd need to be able to prove the light was broken in your defence.