"Green wave" is an idiomatic expression used in traffic circulation that refers to:

A green wave occurs when a series of traffic lights (usually three or more) are coordinated to allow continuous traffic flow over several intersections in one main direction.

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Curiously the same expression is used also in other languages such as Italian “onda verde”, French, “vague verte”, Spanish “ola verde”, German "grüne Welle" and Dutch "groene golf".

Where does “green wave” come from. Was it originally a foreign expression adopted by English speaking countries, or was it coined in English and then spread abroad?

  • 1
    That’s called “Timed traffic lights”
    – Jim
    Jul 20, 2018 at 13:53
  • 1
    @JanusBahsJacquet: The title of the Hebrew article, גל ירוק (roughly /gal ja'rok/ in IPA), also literally means "(a) green wave".
    – ruakh
    Jul 20, 2018 at 14:59
  • 1
    @TripeHound - I agree, the metaphor is clear, but it must have started somewhere by someone. And the fact that the same metaphor is used internationally, makes the issue even more intriguing in my opinion.
    – user 66974
    Jul 20, 2018 at 15:03
  • 5
    I must say, as someone who grew up in Southern California when synchronization of traffic lights was much in the news, and who lives now in Washington, where the failure of the computer that manages the timing of traffic lights in one of the suburban counties was also much in the news, that I have never heard the term green wave until just now, nor seen it in print. I always just said the lights are synced or the lights are timed in this or that region.
    – choster
    Jul 20, 2018 at 15:09
  • 2
    I concur that "green wave" is a European term. The top three scholarly hits I've gotten are in Italy, Denmark, and Hungary. The earliest I've found so far is UK 1991.
    – shoover
    Jul 20, 2018 at 17:41

4 Answers 4


The earliest use I could find in English of 'green wave', with the sense of "coordinated traffic signals", ascribes the origin of the phrase to Germany, and refers to streetcar railway operations in 1927 Chicago:

Other interesting features of the Chicago operation were the famous co-ordinated traffic signal system — we say in Germany the Green wave"

Electric Railway Journal, January 14, 1928, p 95.

  • Nicely found - I found earlier references to "grune Welle" in German, but nothing to do with transport. Jul 23, 2018 at 13:52
  • I too remember this from when I lived for a time in Germany in the '70s. I hadn't heard it in the U.S., but I felt entitled to translate it to my country and still use it today. Most Americans find it an odd usage, and some require explanation for what ought to be perfectly obvious.
    – Robusto
    Jul 24, 2018 at 18:12

"the term Green wave has also been applied to railroad travel. For several years starting in the 1960s, the German Federal Railway maintained an advertising campaign featuring the slogan garantiert grüne Welle (Guaranteed Green Wave), which communicated the notion of speed, limited delays and open track blocks to potential customers choosing between train and automobile travel, and was featured prominently in promotional materials ranging from posters to radio jingles."


"Henry A. Barnes (December 16, 1906 – September 1968) was an American traffic engineer and commissioner who served in many cities, including Flint, Michigan; Denver, Colorado; Baltimore, Maryland; and New York City. Barnes was responsible for many innovations in applied traffic engineering, including the Green Wave of coordinated traffic signals..."


"During 1965, there was a substantial increase in the application of signalling systems in Croatia, since the company "Nikola Tesla" started to use their own capacities to develop and produce the devices for independent, detecting and co-ordinated control. In 1965, the first "green wave" (phased traffic lights) was installed along the Brace Kavurica Street, controlling traffic by the devices produced in the above mentioned company. The exchange which coordinated the operation of devices was installed in the police building in Dordiceva street. By extending the zone to the two neighbouring directions, two "green waves" (phased traffic lights) were formed in the opposite direction. The main exchange was moved to Marticeva Street. Today, there is a new microprocessing zone exchange which controls all the local signalling devices in the city centre. "


  • Thanks for the edit @user070221! I'm still very new to StackExchange...and lazy to boot :)
    – bookmanu
    Jul 20, 2018 at 16:33
  • The site, revolvy, copies a lot of their material from Wikipedia. Luckily, they do cite their sources, but the two excerpts you quoted are directly from Wikipedia. EDIT. No, after checking some other articles, Revolvy just copies everything from Wikipedia.
    – Mari-Lou A
    Jul 22, 2018 at 19:59

In the U.S.:

Signal Timing U.S. dept. of Transportation

Managing Traffic Flow Through Signal Timing by S. Lawrence Paulson

It's a commuter's dream: The avenue is thick with traffic, but green lights appear with regularity. Traffic flows smoothly, and lane changing is minimal. Tailgating is rare. When a red light does appear, no one tries to sneak through. Driving seems almost ... civilized.

It sounds like a miracle, but it may just be another success story resulting from traffic signal management, one of the most cost-effective ways of keeping traffic moving smoothly and making streets safer.

Traffic signal management can be defined as using improved tools, techniques, and equipment to make existing traffic signal control systems operate more efficiently.

In Am spoken English typically called traffic light synchronization. Green wave appears to be of Eu origin. I could find no expression origin.


Each country developed the phrase independently.

Language adaptations come from the environment of which the language is spoken. And the internetz has proven how adaptive our language is.

After motor vehicle transport becoming an international norm; whose to say that the luck of riding a green wave would not present itself?

Each country has coastal exposure giving ground to have a word to describe the movement of a wave and a green light is the universal colour to communicate continuing traffic movement.

Given those circumstances I do not think it necessary that the phrase had to have physical vectors of people who used the phrase to spread, but it was possible to independently develop the phrase as the culture had already pollinated via the spread of transport technology.

Long shot. A fun concept to ponder. I look forward to hearing the answer.

  • Since I dislike people down-voting without bothering to explain, to me that would have sounded tenuous as a Comment, let alone an Answer. Jul 26, 2018 at 23:54

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