What Is the Green Wave for Bikes? How Retimed Traffic Lights Change Cities
On Manhattan’s Third Avenue in the Upper East Side and East Harlem, I biked through 40 green lights in a row.
That’s because, when the city put in a new protected bike lane starting at 59th St, they also retimed traffic lights. Instead of being set to 25 miles per hour, the signals are now synced for a steady 15 mph, the average speed of a cyclist.
I’ve seen other cyclists and advocates call this a “green wave.”
This is a simple, cost-effective change that I think will have outsized results not only for cyclists, but also for making streets safer and reducing car trips.
As cities like New York continue to address the problems created by decades of car-dependent streets, they’re experimenting with new forms of bike infrastructure. This is one of the simplest I can think of.
What is the “Green Wave” for Cyclists?
A green wave is when traffic signals are coordinated to favor a certain speed, allowing vehicles traveling at that pace to hit consecutive green lights.
Traditionally, lights have been timed for cars moving around 25 mph. Now, some cities are rethinking this for cyclists, retiming signals to match a more realistic speed of around 15 mph.
That shift flips the experience of biking in the city. Instead of a stop-and-go grind, you can keep steady momentum.
All cities where people often move short distances (three miles or less) will benefit from prioritizing bike infrastructure like this.
The City-Wide Benefits of Retiming Lights for Those on Bikes
Of course, as someone who bikes as my main form of transportation, I loved this. But the benefits extend to everybody.
Energy + Momentum
Cyclists power themselves. For a driver, stopping and starting is annoying. For a cyclist, it’s physically tiring. By letting riders maintain momentum, green waves make biking less of a workout and more of a smooth, reliable way to get around. That efficiency is often what tips someone from “maybe I’ll bike” to actually choosing it.
Faster Cycling Trips
With fewer interruptions, biking becomes a genuinely competitive option compared to driving short distances.
Genuinely, what used to be a 20-minute bike ride up First Avenue is now 15 minutes up Third Avenue.
Less Traffic For Everyone
When cycling is a safer, faster, more enjoyable, and less tiring option, more people will do it.
That means instead of calling a taxi or rideshare, some people will bike. Maybe a car owner will leave it in the garage and take a bike instead for the same reason.
The best way to reduce traffic is to improve the alternatives to taking cars.
Every trip shifted from car to bike reduces traffic jams, cuts emissions, and frees up road space. Even for people who never plan to bike, this means cleaner air, quieter streets, and shorter car trips because fewer people are stuck in traffic ahead of them.
Encourages Safe Cycling and Driving Speeds
When lights are timed for 15 mph, both cyclists and drivers are nudged toward safer speeds.
E-bikes are less likely to go above 15-20mph, as they’ll just run into more red lights, and drivers have less reason to dart through yellows or reds, as they’ll get stuck at the next light.
The design encourages safer behavior for everyone.
There’s also a lot of talk about cyclists running red lights. In this article I share why cyclists should be able to run red lights. But as it relates to the green wave, cyclists won’t run red if they don’t hit them.
Riders aren’t forced to dart through reds, and drivers can’t speed without immediately getting stuck at the next light. This reduces risky behavior, lowers crash risk, and creates a calmer street environment overall.
When cyclists can keep moving, they’re less likely to clog intersections or weave unpredictably to beat lights. A smoother ride creates a predictable flow that works better for everyone. It also makes bike lanes more appealing, which encourages even more people to ride.
In urban planning terms, this is a classic example of self-enforcing infrastructure: design that makes the safer, greener, safer choice the easier choice.
Second-Order Benefits of Green Waves
By taking cars off the road, this type of infrastructure means cleaner air, quieter streets, less honking, and fewer cars idling in traffic spewing pollution.
Designing signals around cycling makes biking more accessible to a wider group of people. For example, in my article on the benefits of protected bike lanes, I shared the research on how cycling infrastructure increases the number of women riding bikes as transportation.
When riding feels safer and more predictable, it attracts people who might otherwise avoid it.
Common Critiques of Timing Lights For 15MPH
Some of these are pulled directly from the comments on my TikTok video on this, which went crazy with both supporters and haters.
“Cyclists Run Red Lights”
Therefore, I suppose the logic is that cyclists don’t deserve infrastructure.
I share a different perspective in this article.
My overarching point is that cyclists exist is a road environment, with road rules designed for cars. We need to look at why cyclists, many of whom also drive and do not go through red lights in a car, typically go through lights.
Green waves help address this by making compliance easy. If I can cruise through dozens of greens in a row at a steady pace, then I will stop at a red because I’m tired!
The design encourages safe and predictable behavior without the need for constant enforcement.
“Stop and Go Traffic BurnS More Gas”
Another critique is that retiming lights for bikes will slow down cars.
This is a good thought, and a fair critique, but it misses the forest for the trees. The most fuel-efficient car trip is a bike trip. By incentivizing cycling, you take entire cars off the road.
You also reduce traffic, which means cars spend less time in gridlock, which means far more idling than stopping more frequently for lights. In many urban areas, most car trips are short anyway, so the difference in travel time is negligible.
“Not Everyone Can Ride Bikes”
Some people also argue that not everyone bikes, so why design signals for cyclists?
Not every piece of infrastructure is meant to serve every user equally. Just as not everyone drives or takes the bus or can get down the stairs on the subway, not everyone will bike.
But everyone benefits from cleaner air, reduced congestion, and safer streets.
I would argue that people with disabilities benefit more from this than car infrastructure. Mobility devices exist. I’ve seen countless powered wheelchairs in bike lanes. These riders gain the same benefits from smoother, safer trips that cyclists do. Bike infrastructure often ends up serving a broader range of people than critics assume.
Designing Cities for People, Not Just Cars
Retiming traffic lights are another piece of the story about what cities choose to prioritize.
For decades, every detail of the street environment has been designed around moving cars quickly. The result was cars moving very slowly, stuck in traffic, because everybody needed a car to get places.
The green wave shows how rethinking even small details can flip that script.
When we design streets around people instead of just vehicles, the benefits ripple outward. Biking becomes safer and more appealing. Streets become calmer and cleaner. Traffic flow improves for everyone.
If a simple change like signal timing can transform a busy avenue, imagine what could happen if cities applied that same mindset to every part of the street.
More places should test green waves because they are cheap, effective, and make urban life better for all. But remember this is just one part of the equation. We also need access to bikes and protected bike lanes to make it safe.
If you’re in New York and ready to ride the green wave, check out my guide on using Citi Bike.
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