Six things you didn’t know about traffic lights

Carlton Boyce / 22 June 2016 ( 31 March 2017 )

Can you drive through a red traffic light if you think they are broken and stuck on red? Can emergency service vehicles change the lights to green?



Traffic lights are so commonplace as to be unremarkable, which is a shame as they’re absolutely fascinating!

Here are my six favourite traffic light facts:

1. The first traffic lights

The very first traffic lights were installed in 1868 outside the Houses of Parliament in London and were gas-powered and operated by hand. They weren’t a huge success as they exploded, injuring or killing the policeman (history is unclear as to the extent of his injuries) operating them.

The first electric traffic lights were installed at a four-way junction in Cleveland, Ohio in 1914 and were, again, operated by a police officer.

Fully automatic traffic lights were first used in London at Piccadilly Circus in 1926 or Wolverhampton in 1927 – depending on who you believe.

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2. Why red, amber and green?

The use of red and green signals had been used on the railways for years, so it made sense to extend their use to the road network too. The trouble was that the two-light system didn’t give drivers any warning, and accidents were common on congested city roads.

The amber light was first added in 1920 in Detroit to give drivers a warning that the lights were due to change. Their use was quickly rolled out worldwide as the number of accidents dropped sharply wherever they were installed.

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3. The traffic light patent

General Electric owns the patent for the basic three-way traffic light system, having bought it for a paltry $40,000 from Garrett Morgan who filed patent number 1,475,024 on 20 November 1923.

His system was revolutionary because it stopped traffic from all directions with a third signal temporarily, allowing the junction to clear before activating the next red or green signal as appropriate; previous systems had simply gone from red to green without pause, leading to accidents. The system was later modified further with the addition of an amber signal (see above).

Garrett Morgan also invented the gas mask in 1912 and he is credited with saving thousands of lives as a result of his two inventions.

4. Which UK city has the most traffic lights?

The city of Leicester is thought to have more traffic lights than any other city in the United Kingdom. It was also the first city to deploy both traffic lights and traffic wardens on unsuspecting motorists.

5. The urban myth

Received wisdom has it that you can drive through a red traffic light if you think they are broken and stuck on red.

This isn’t true: the law is very clear and says that you must not pass through a red traffic light unless directed to do so by a ‘a constable in uniform or a traffic warden‘.

Common-sense says that you should be able to drive through a traffic light that is stuck on red but if you do and are prosecuted, you will need to prove that the traffic lights were faulty, and that you had no option but to proceed through them in order to mount a defence.

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6. Can the police drive through a red light?

The police, and other emergency services including fire and rescue, ambulance, bomb and explosive disposal, national blood service, Serious Organised Crime Agency (SOCA) and special forces are allowed to treat a red light as a ‘Give Way’ signal if they are on an emergency call.  

Some countries – but not the United Kingdom – have an override on their traffic lights, changing them to green to allow the emergency services through more safely by stopping all other traffic. 

Next article: Five things to do if you are pulled over by the police >>>

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