Traffic lights.

The first traffic lights:
The first traffic light to regulate the auto traffic was installed in the centre of London in 1868. It was made with gas lamps.
In 1914, in the American city of Cleveland, electricity was used instead of gas lamps, because they were really dangerous.

Control of traffic:The traffic light can use two different systems to control the traffic:
- OPEN SYSTEM: this is the most simple, there is a red light in a street and a green light in another street during the same period of time.
- CLOSE SYSTEM: this is used to decrease the traffic in the busiest roads.

Traffic lights for blind people:

It is a beep which begins to sound when the green light is on.Robot and ecologist traffic lights:

They can detect some break down and call the technical service. And the future traffic light will waste less energy as it will be made with luminescent diode.


Why are the colour red and green used?

Birmingham's railway technical chose this colour in a meeting in 1841: red means "stop", yellow means "attention" and green means " free path".



A curiosity:
The Romans soldiers used a particular traffic light which made the communication between the legions in a battle easie.