Why traffic signal red = stop, green = go? Does this go back to ancient Rome? see more detail...?

Question

I got asked this question and was only able to trace use of red/green to railroad signals. The asker also said that the ancient Romans must have had a lot of traffic on the sophisticated roadways built (e.g. in Pompeii), so how did they control traffic at intersections? Does anyone have information that might help answer what the Romans did do?

Thanks in advance!

Answer 1

Uh...to control traffic.

Answer 2

On 10 December 1868, the first traffic lights were installed outside the British Houses of Parliament in London, by the railway engineer J.P. Knight. They resembled railway signals of the time, with semaphore arms and red and green gas lamps for night use. The gas lantern was turned with a lever at its base so that the appropriate light faced traffic. Unfortunately, it exploded on 2 January 1869, injuring the policeman who was operating it.

On Potsdamer Platz, Berlin Germany, it is widely claimed (though this is subject to some disagreement), that the world's first electric street lights were installed there in 1882. What is not refuted is that Europe's first traffic lights were erected there in 1924 in an attempt to control the sheer volume of traffic passing through. These lights were mounted on a five-sided 8.5 metre high tower, at the top of which a policeman sat in a small cabin and switched the lights manually, though they were automated after a few years (a replica of this tower was erected in the late 1990s close to its original location).


The Romans considered a well organized road network and an efficient traffic system as basic elements for proper imperial administration. Consequently, they invested great efforts in the form of resources, planning, labor and technological skill in road building.
The road stations and guard posts, erected at necessary intervals and key points, assured the secure and ordered functioning of traffic.

Sorry nothing about traffic signals in Roman times.

Answer 3

I don't know about the romans but don't you think it's just linked to our colour associations? I.e. red = stop, danger, no. green = go, yes, good. ? Makes sense to me

Answer 4

Red and Green are totally different colors... you can't mistake them... that is the reason they were chosen they are complete opposites... red: hot and green: cool