Mission Surf Report

October 5, 2017

Making Waves

Pedal, pedal, pedal, coast, feather the break, stop, wait, repeat. Red lights are the bane of the urban commuter’s existence, yours and mine, but let’s backpedal for a minute. Despite the deceptive title of this post, we’re not talking about board shorts, single fins, and beach blanket bingo. Nope. This is still a bike site. We’re talking about green light after green light after green light. Surfing the bicycle green waves of San Francisco, none of which currently reside in Ocean Beach. 

Although there is no formal definition, a green wave is loosely defined by the coordination of 2 or more green lights in a row, allowing traffic to flow continuously down a given street.

The term was actually coined in the 1960s by the Deutsche Bundesbahn (German Federal Railway), who used the term “garantiert grüne Welle” (Guaranteed Green Wave) in their advertisements to entice the general public to choose rail over automobile due to it’s limited delays and open track blocks.


Nowadays, however, the green wave is a concept largely associated with motor vehicles, and actually boasts plenty of great benefits for them: lower fuel consumption, less time waiting in traffic, lower harmful emissions, etc.

As great as that is, we’re not here to talk about the cars...or the trains.


A Shift in Focus

As with most things, before we move forward, we must first look back. It was the early 2000’s in a city renowned for it’s progressive bicycle infrastructure. Yep, I’m talking about Copenhagen. They’d already implemented some of the finest, most efficient bike lanes the world had to offer and were out to tackle a whole other beast: the flow of traffic. 


Legend has it there was a brainstorm spearheaded by city councilman and former actor Klaus Bondam that led to the borrowing and implementation of motor vehicle green wave principles but for a far greater cause. The velocipede agenda.


Photo Credit: Copenhagenize Design Co.

Experimental as it was, the proof was in the pudding. By implementing green waves  on high traffic streets during rush hour, they had yielded an increase in average commute speed, massively reduced stops for cyclists along the wave, and created an overall more enjoyable ride. A huge step in the right direction for cycling cities all over the world. Copenhagen had yet again set the bar for cycling infrastructure in an urban city.You can read a full case study here.


So where do we fit in?

Flash forward from the early 2000’s in Copenhagen to the slightly later, but still early 2000’s in San Francisco. The year was 2009 and SFMTA was hot on the tails of the Danish, installing the city’s first green wave on our very own Valencia Street. 

The signs declaring the waves existence may not make themselves the most apparent, but it’s difficult not to notice that you’re hitting upwards of 8 green lights in a row. A feeling much akin to surfing, but without all the “locals only” stuff. Throw a shaka to your fellow cyclist, cause it’s a party wave. Good vibes all around.

Not surprisingly, the response from the cycling community in San Francisco was overwhelmingly positive. As a result, year by year, we would see more green waves pop up. Instead of riding to work, the commuters of San Francisco were now surfing.


Take Folsom Street for instance:


Is dialing 7 red lights all the way down to 0 on the commute across Folsom a score for the cyclists? Absolutely. But being the infrastructure nerds we are here at Mission Bicycle, we had to ask a few questions. For that, we reached out to Laura Stonehill,  Assistant Engineer at the SF Municipal Transportation Agency to see what the process was like from a city planning perspective.


Q&A With Laura Stonehill at SFMTA

First, I’m wondering what city inspired us to implement green waves for cyclists? I’m told green waves have long been a thing for cars, and even longer for trains.  

When I say “green wave” I mean “green wave for bicyclists”. We have lots of green waves for cars too- think Franklin Street, etc. The general term for all of this would be signal coordination. Signal coordination could also be used to slow down vehicles, for traffic calming purposes.

I don’t have too much insight into what inspired my coworkers to install the first green wave on Valencia Street, but I can take an educated guess. Valencia Street is a very popular bike corridor and in December 2009 the bus was removed from this corridor. I’m guessing my coworkers saw an opportunity to improve cyclist comfort on a street that had lots of cyclists traffic, without impacting transit. There are vehicles on Valencia too, but there are parallel streets that are faster through-streets for motorists.


Have any other cities reached out to us for help in creating green waves of their own?

I’ve had cities contact me about our methodology, including NYC and San Jose. I presented a poster about green waves at the Pro Walk Pro Bike Pro Place Conference last fall and lots of cities were interested. 



A certain source (Ahem, Wiki) claims that Valencia street was one of the first green waves to work simultaneously in both directions. Is that true? If so, how were we able to accomplish this?

 Looking at my emails, a coworker said Amsterdam had a two-way green wave in 2007. Our first green wave, on Valencia, was also two-way, and was installed in 2009. I don’t know if Amsterdam was the first though.

 Actually, all of our green waves on two-way streets are two-way green waves. It’s definitely easier to design a green wave with a wide band (a green wave that encompasses all or most of a signal’s green time) on a one-way street, but it’s not that hard on a two way street if the design speeds and distance between signals work out. Worst case, the band becomes narrower (only bikes that are traveling in a certain part of the green phase will hit the next green light.)


How many green waves, in total, do we have in San Francisco? Which streets do these run?

I would say we have 7 green waves, since the Folsom from 11th to 12th isn’t long enough to really be called a greenwave.


Map of SF Green Waves:HERE


Is there any research to show that green waves have improved the safety of cyclists? Or is it simply making our commutes quicker and more enjoyable?

The only before-after data we collected was just to show that the green waves were functioning as designed. We have heard anecdotally (and I’ve experienced personally) that they make bike travel quicker and more enjoyable. I don’t know if any other cities or organizations have done more safety research.


Are there plans to create more green waves in the future? If so, what areas make the most sense from a city planning perspective? We feel like we’ve been well treated in the Mission. 

I am not aware of any plans to install more green waves, but the SFMTA is currently starting a big project to retime all of our signals in the downtown area (SOMA and north of Market in the downtown area), so it’s possible more may be added. In general, places where green waves work are places with bike lanes, with all signalized intersections with the signals on the same system (with the same cycle length and “clock”), where transit doesn’t have conflicting needs, where we have high volumes of cyclists, etc.


I know this is for a bike blog, but many people reading are probably also at least part-time motorists. Have the green waves had any adverse effects on the flow of motor vehicle traffic? As far as I can see, things seem to move along fine. 

The corridors where we implemented green waves weren’t optimized for vehicles beforehand (the offsets were all pretty random), so the bike green waves didn’t really make anything worse for vehicles. One green wave disrupted some progression on an intersecting street, and a taxi driver who is very familiar with our signal timing called us to ask about the change. When we explained the improvement for cyclists, he was satisfied. Other than that, I haven’t heard anything about vehicles being impacted.



Time is money

So how much “money” is the SFMTA saving me every year? Well, let’s look at the Folsom case study for a little help. The “before” stats show our rider moving along from 14th to 24th in 5 minutes and 56 seconds at an average speed of 10mph, whereas the “after” stats have the rider completing the same trek in just 5 minutes and 18 seconds. Okay, saving 38 seconds isn’t exactly a game changer, but let’s extrapolate that.

Let’s say you bike just that one stretch of road 2 times a day, to and from work, 4 times a week. You work the occasional day from your home office (must be nice) and call in sick every now and then. If there’s 52 weeks in the year, we’re looking at 208 days you save 38 seconds twice. You’re saving yourself 4.39111111 hours a year. Your mind still isn’t blown, and that’s okay.

But what could possibly make that okay? Wasn’t saving time the whole point of this article? Plot twist. Nope, and here’s why: Because we don’t ride bikes to work for the sole purpose of saving hours out of the year. We ride our bikes to work because we love riding bikes. We ride our bikes to work because it’s fun.

Although the green waves may not save us a ridiculous amount of time on our daily commute, They are proof that SFMTA does care about the urban commuter and they manage to come through with something far better than saving time: They make your commute exponentially more enjoyable. The saving 4.39111111 hours of your life a year is just a bonus. The real prize is hitting zero reds from end to end on a long stretch of road.

It’s called surfing, and you can’t help but smile when it happens.