# Traffic light "green waves"



## tradephoric (Jan 27, 2012)

A green wave occurs when traffic lights are coordinated so that you hit a string of green lights. Do you know of any streets with long green waves? Here's an example from Detroit:

*Consecutive greens: * 16*
Wave distance: *3.8 miles* 
Location: *M-10 (Detroit, Michigan)


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## ChrisZwolle (May 7, 2006)

55 green lights in Manhattan:


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## x-type (Aug 19, 2005)

Zagreb
12 lights westbound (2,3km)
12 lights eastbound (1,8 km)

unfortunately, lousy video, I couldn't find better.


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## Verso (Jun 5, 2006)

There used to be a road in Ljubljana with a green wave (_Tržaška cesta_), but not any more, at least not that I'm aware of.


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## tradephoric (Jan 27, 2012)

Here’s a lengthy green wave along Detroit’s iconic Woodward Avenue. 

*Consecutive greens:* 69
*Wave distance:* 20.7 miles 
*Location: *Woodward Avenue (Detroit, Michigan)


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## tradephoric (Jan 27, 2012)

This one is pretty epic! This cabbie drives 1st Avenue from Houston Street to 125th without hitting a red light. 

*Consecutive greens:* 121
*Wave distance:* 6.3 miles
*Location: *1st Avenue (NYC)


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## ChrisZwolle (May 7, 2006)

What are the chances of getting all lights green during the day? The Woodward Avenue one was during the day, and a much longer distance.


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## ChrisZwolle (May 7, 2006)

Green waves were common in the Netherlands in the 1990s and early 2000s, but disappeared mostly due to bus priority on crossing roads. 

They replaced green waves with network traffic signal coordination, to reduce delays over a network, instead of a single road. Some use advisory speed limits so you can hit the next light green. 

Some mostly rural traffic signals have detectors for semi trucks, so they keep the light green if a semi truck approaches.

I filmed this system with advisory speed limits in my city a few years ago:


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## Verso (Jun 5, 2006)

tradephoric said:


> This one is pretty epic! This cabbie drives 1st Avenue from Houston Street to 125th without hitting a red light.
> 
> *Consecutive greens:* 121
> *Wave distance:* 6.3 miles


That's a lot of traffic lights! What the heck is that "chimney" at 4:09?


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## verreme (May 16, 2012)

Barcelona has many long (>1 km) green waves. The longest ones are in Gran Via and Carrer d'Aragó; you can drive almost the whole length of these streets without stopping at a red light when traffic is fine. Muntaner, Balmes, Sepúlveda, Mallorca or Rambla de Guipúscoa do also have this feature, at least during the day. At night light syncing is changed and you can't hit a long green wave. The shape of Barcelona's _Eixample_ blocks, which are all square and have wide streets between them, is definitely of great help.

In some of these streets green waves do also work for pedestrians. Walking at a reasonable pace (4-5 km/h) all crosswalks are green for much of Gran Via or Aragó.

I shot this video back in 2012. I was lucky that the lights at the end of Carrer d'Aragó and Plaça d'Espanya were green; in fact I almost ran a red. However when traffic was this light crossing the city stopping just 3 or 4 times (out of 30+ lights) was feasible. Today there are roadworks at Plaça de les Glòries and that means some extra red lights, but when the tunnel that's now U/C is finished the route Gran Via-Marina-Aragó-Tarragona-Gran Via (freeway-to-freeway) will again be almost all green. That's quite a long way.






Valencia is another Spanish city that has very long green waves on the main streets. Traffic is usually better than in Barcelona so driving there is a pleasure.


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## tradephoric (Jan 27, 2012)

The great thing about Woodward Avenue is that you can get green waves in both directions of travel. The best way to exemplify this is with a time-distance diagram. I know this doesn't look that impressive, but it's rare for a corridor to have long "green waves" in BOTH directions of travel.


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## niskogradnja (Feb 8, 2010)

In Switzerland I know only there are a lot of red wawes in the city I live and in Geneva. A green wawe would only disturb the swiss people, as they love to wait in a line for anything. When I go to work at 5.30AM I have to wait at a couple of traffic lights, even if there are no other vehicles in the intersection other then mine.


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## tradephoric (Jan 27, 2012)

You can hit a green wave driving down Central in Albuquerque, New Mexico.


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## tradephoric (Jan 27, 2012)

ChrisZwolle said:


> What are the chances of getting all lights green during the day?


It's probably a lot harder to hit a good green wave in Manhattan during the middle of the day but it does happen. This guy drove 3rd Avenue from 53rd to 99th street in the middle of the day without hitting a red light.


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## tradephoric (Jan 27, 2012)

An UBER driver cruises through 236 consecutive green lights in Manhattan. The story was picked up by many national news outlets.

*Consecutive greens: *236*
Wave distance: *12.3 miles* 
Location: *Manhattan (Start at Mt Morris Park & 121st.. cruises down 5th Ave, 6th Ave, and 2nd Ave).






A sped up version can be viewed here:
http://abc7ny.com/traffic/uber-driv...-240-consecutive-green-lights-in-nyc/1676555/


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## OulaL (May 2, 2012)

A green wave is often a myth.

It is possible if certain conditions are met, and even then it is usually possible in one direction at a time only; to have it possible in both directions is very rare.

What I mean by myth is that drivers who don't bother with simple mathematics often believe that it is possible anytime and anywhere; and as a result, they believe that the lack of it is intentional laziness or malevolence from the part of the street administration; and the frustration of such laziness or malevolence is then shown on social media.


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## MattiG (Feb 11, 2011)

OulaL said:


> A green wave is often a myth.
> 
> It is possible if certain conditions are met, and even then it is usually possible in one direction at a time only; to have it possible in both directions is very rare.


True. A bidirectional green wave is sometimes achievable on parallel one-way streets apart enough. Such as in Helsinki on Lönnrotinkatu and Uudenmaankatu which are quite short streets and two blocks apart. This does not come for free: The waiting time of the crossing traffic is excessive at several crossings.

The more the city differs from a grid plan with equal-size blocks, the more mission impossible a green wave is to be implemented on more than one street.


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## MattiG (Feb 11, 2011)

Here is a nice summary slide deck about the problematic to create a bidirectional green wave:

http://www.liikennevalot.info/opi/download/6A%20Traffic%20Signal%20coordination.ppt


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## tradephoric (Jan 27, 2012)

In theory, any two-way street with evenly spaced traffic signals and a constant speed limit is capable of bidirectional green waves. So why isn’t it more common? The crux of the problem is traffic signals are spaced too closely together to make bidirectional green waves practical along most two-way streets. As traffic signals get closer, the required cycle length to achieve good green waves gets shorter. There’s a pretty simple formula to determine if a two-way road is capable of achieving bidirectional green waves. 

Max cycle length = 2 X travel time.

For example, if it takes 30 seconds to drive between traffic signals, the maximum cycle length that could achieve bidirectional green waves is 60 seconds. Unfortunately, a 60 second cycle length is often too short in the real world (won’t fit pedestrian times, not enough time to fit left-turn phases, too much wasted green time for yellow/red safety intervals). There are a lot of two-way roads out there where it takes less than 30 seconds to drive between traffic signals. It doesn’t matter if the speed limit is 25 mph or 55 mph, if it’s only taking 30 seconds to drive between traffic signals you are pretty much screwed (assuming the traffic signals are simultaneously stopping both directions of travel). Keep in mind, a lot of streets run 120 second cycle lengths during rush hour to maximize throughput. In that case, it would need to take 60 seconds to drive between traffic signals to achieve a bidirectional green wave.


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## OulaL (May 2, 2012)

The minor streets crossing the main street should be somewhat equal in traffic density, because the green phases given to each of them must be equal.

If some of the minor streets have a significantly greater traffic density than others, and a green wave is still wanted, then a choice must be made: whether the green phase given to the minor streets is based on that required by those with the greater density, or those with the smaller.

If the green phase is too long, then time is wasted without anybody moving. This causes frustration in those drivers who are forced to wait, seemingly because of nothing.

If the green phase is too short, that obviously causes congestion in that direction.


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## LegendMeadow (Nov 2, 2015)

This is how they do it in Las Vegas.

(sorry can't post links, so please search in youtube: "AMERICA REVEALED | Las Vegas Gridlock | PBS")

It's the same concept as the green light wave.


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## tradephoric (Jan 27, 2012)

Driving for nearly an hour along Woodward Avenue without hitting a red light.

*Consecutive greens: *124
*Wave distance:* 40.0 miles
*Location: *Woodward Avenue, Detroit


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## 1080 (Jan 22, 2019)

Just came across this video showing 35 consecutive green lights on a two-way street within heavy build-up area of Hamburg. Never seen such a long green wave on a european two-way street before. I've doubts if it works in both ways though. 

*Consecutive greens:* 35
*Wave distance:* 7.2 km
*Location:* Ahrensburger Straße, Hamburg

https://www.youtube.com/watch?v=ImOdmCcrjyw


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## satanism (Mar 6, 2011)

On a very good day you could cross Bratislava from Zlate Piesky exit of D1 to Lamac exit of D2 entirely through green wave. That's about 13km right through the city.I don't have a video though


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## snowdog (Mar 27, 2011)

tradephoric said:


> Driving for nearly an hour along Woodward Avenue without hitting a red light.
> 
> *Consecutive greens: *124
> *Wave distance:* 40.0 miles
> ...


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## Ni3lS (Jun 29, 2007)

tradephoric said:


> Driving for nearly an hour along Woodward Avenue without hitting a red light.
> 
> *Consecutive greens: *124
> *Wave distance:* 40.0 miles
> *Location: *Woodward Avenue, Detroit


Crazy. I remember driving a shorter stretch of Woodward last September and only hitting the first red light downtown. To be fair you probably would want to keep driving on some parts of that road anyway if you see the burned out and shot up real estate alongside it :shifty:

I noticed yesterday that in Stuttgart they installed a matrix sign indicating the speed you should drive in order to hit the next green light without braking. This is on the B14 in the direction of the city (from B10), a three-lane city road. For it to work in practice though everyone needs to 'abide' otherwise the long lines at the red light ahead will slow down traffic behind it because they are accelerating from a standstill. For example yesterday the sign indicated to me I should drive 30 km/h (50 km/h speed limit) in order to hit the next green. I drove 50 km/h and hit the line at the red light, which turned green a couple of seconds later.


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