Surfing the Green Wave: CDOT Pilots Bike-Friendly Signal Timing on Wells

Here’s another clever new idea from the Chicago Department of Transportation. This week, they re-timed the stoplights along Wells Street between Huron Street and Wacker Drive in River North, so that southbound bicyclists who maintain a 12 mph pace get an unbroken series of greens.

Known as a “green wave,” this kind of signal timing has been common on main streets in Copenhagen since 2007, and San Francisco has recently implemented it on several roadways. Not only does it make bicycling more efficient, it also reduces the chances that bike riders will endanger themselves by blowing red lights.

Wells was a logical place to pilot a green wave in Chicago, according to Mike Amsden, CDOT’s assistant director of transportation planning. “After Milwaukee Avenue, it’s probably the second most popular on-street bike commuting route in the city,” he said, noting that cyclists account for up to 38 percent of all traffic during the morning rush. The street has buffered bike lanes and is classified as a Crosstown Route in the city’s bike plan, and several Divvy stations are nearby.

Previously, the stoplights were timed so that a cyclist pedaling at 12 mph starting from a green at Huron would hit a red light at almost every intersection. “I think there was a lot of frustration with the number of lights you’d hit and have to wait at, and hopefully that’s changed,” Amsden said. Note that the Wacker Drive stoplight is not part of the wave, so you’ll tend to get a red when you arrive there after a series of greens.

Signage at the start of the Wells Street Green Wave.

The new timing also benefits drivers, Amsden said. If they travel at about 25 mph, they’ll also hit every green. That’s an incentive for motorists to avoid speeding, and it should also reduce red light running by drivers, making the street safer for everybody. Between 2009 and 2013, there were 35 crashes on this stretch that involved red light running. Amsden added that the new signal timing doesn’t hurt traffic flow on major cross streets and, in some cases, it improves it.

I rode the Wells several times in the late afternoon today and found that the green wave timing generally functions the way it’s supposed to. Although my default commuting speed on my cruiser bike is 10 mph, it was fun to hustle a bit in order to get to the intersections while the lights were still green. The only thing that slowed me down and made me miss my signal was when drivers blocked the bike lane.

Take a spin on the Emerald Half Mile when you get a chance, and let us know what you think in the comments section.

  • jay b

    That’s great- I wish more streets were timed like this- for everyone’s benefit

  • Eli N

    I noticed these on Thursday and wondered if they were new, but I’m in that area so rarely that I figured I probably just hadn’t noticed them before.

    Like you, I ran into problems with drivers blocking the route (in my case it was cross-traffic blocking the intersections even after their light had turned red) which threw off my timing somewhat, but for intersections which were clear it worked quite well. In the past I’ve always seemed to hit every light along this stretch so I’m glad of the improvement.

  • kastigar

    What about north-bound cyclists? Doesn’t this make it worse?

    Many years ago when I had to drive downtown the lights on LaSalle Street (between North Avenue and downtown) were set on “waves” – to benefit southbound in the morning and northbound in the evening. If worked great in that directions but made the opposite directions a real nightmare. I don’t know if this stop light waving still exists on LaSalle Street or not.

  • Fred

    It should be noted that cars going 12mph also will not have to stop at any red lights.

  • I don’t know whether a green wave could function on a two-way street, but Wells south of Huron is one-way southbound. North of Huron it’s a two-way, with bike lanes in both directions.

  • Bernard Finucane

    The “Grüne Welle” has been SOP in Germany for decades. It’s usually set at 40 kph though.

  • Bernard Finucane

    The method is often used to favor rush hour traffic. So the same street would vary during the day depending on where people want to go.

  • SGonzalez

    Or 36 mph or 48 mph

  • Cameron Puetz

    Wells is one-way southbound south of Eerie, so the only light in the project area that would have northbound riders is Huron.

  • Cameron Puetz

    Coordinating light timing to reduce stops isn’t really a new thing (although normally lights are timed to the speed limit to benefit cars). In many cities it’s standard operating procedure and has been for awhile. It’s done to both reduce congestion and encourage speed limit compliance. If you drive the speed limit, or bike at half the speed limit, in most cities, you’ll get a green wave. It’s frustrating that it’s taken CDOT this long to take a serious look at signal timing.

  • Cameron Puetz

    It’s SOP lots of places. While it’s normally set for the speed limit, cyclists can usually benefit by going half the speed limit.

  • The problem with CDOT doing more timing projects is that almost every single stoplight is controlled by a thing right on that same street corner with it. You have to go in person and fiddle with it to change the timing.

    Because of this, there’s a streetlight-timing unit who spend one week of the year in each ward of the city rearranging and timing lights.

    If they were all hooked into a central control-room, it would be much easier to do city-wide prioritization, as well as change up a block or two as needed, without sending out a truck with workers to do the change.

  • Matt

    “Traffic signals on Wells have been retimed for bicycle travel speeds of 12 mph and vehicle speeds of 25 mph, CDOT said.”

  • Also noted in the Streetsblog article.

  • I was loading up the comments just now to make the same point: Green waves for drivers are common.

  • tbatts666

    Yeah, first one timed for bikes in the usa right?

  • As the article states, this has been done is San Francisco. It may also exist in some smaller, bike-friendly cities.

  • Ben Jassin

    It seems like the wave has been extended through the loop to at least Van Buuren St. I’ve been able to ride all the way through consistently now; whereas last month, I got stopped in the loop at multiple lights. Can anyone else confirm this?

  • Matt

    Green wave could (and does) work on two-way streets, just a little tougher to implement. “On San Francisco’s Valencia Street, the signals were retimed in early 2009 to provide a green wave in both directions, possibly the first street in the world with a two-way green wave for cyclists.”


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