In a Polk Street world with protected bike lanes...

Thanks to Twitter, I discovered a wonderful new program called "Streetmix" that allows you to design your own streets - in particular designing street widths from a section perspective. Immediately I set out to design the "perfect" Polk Street that might satisfy all the core issues at hand.

See an example of a fully protected bike lane with raised curbs between parking and bike lane - a real cycle track, this time on the Avenue d'Italie in Paris. Avenue d'Italie is 132.5 feet wide (lot-to-lot), so it's more comparable to Van Ness Avenue (125 feet) or Octavia Boulevard (133 feet). Although Polk Street is much narrower (68.75 feet wide lot-to-lot), a recent op-ed in the SF Chron called for a "fabulous - Paris-style avenue". To be fair, the writer later described that it should be like a Parisian "street" or "rue".
Polk Street: CYCLE TRACKS intersection with bus stop and left turn. Image: Urban Life Signs using Streetmix
Polk Street in San Francisco is an important commercial shopping street stretching from Market Street to Aquatic Park. It's also a critical bike pathway between Civic Center and all points south and west to northern neighborhoods like Cow Hollow, Fisherman's Wharf, and the Marina. Other than the Embarcadero Polk Street is the only north-south bike route north of California Street.

There's been a lot of controversy over how to best redesign the street to accommodate all the modes (cars, delivery trucks, buses, bikes, pedestrians, people who are disabled or with strollers), and to address parking needs for businesses (car street parking, car garage parking, bike parking).

A lot of emotional energy has been spent by all sides (merchants, bike advocates, city staff, locals) but one problem remains, no matter what gets built: the geometry will not change. The fact that "upper" Polk Street is 69.5 68.75 feet wide lot line to lot line, and 44.75 feet wide curb to curb is inescapable. The curb-to-curb width in Lower Polk (south of Post Street) is 48.75 feet. Even if the curbs were moved a bit (think expensive) in the Upper Polk segment, there's so little width to play with it wouldn't significantly change the challenges. Simply put, there's not enough room to satisfy all constituents. (note: I may not have the exact street width correct, but it's within 1 foot of the actual width.)

A preferred plan was presented in July 2013 by the SFMTA. The plan tries to blend all the needs together through a combination of bike lanes, sharrows, and a few segments with a buffered bike lanes, and raised curbside buffered bike lanes in one direction at a time. It's not horrible, but it's also not satisfying either; especially if we consider San Francisco a "Transit First" city, not a "Car First" city.

SFMTA did examine a "curbside bikeway" (or buffered bike lane) alternative early on. Through removing parking on one side and partially on the other side, the new bikeways would be a classic unprotected bike lane in one direction and a buffered street level bike lane in the other direction. This is not a true "all cycle track" plan, and one was never presented.

I've used Streetmix to show what it might have looked like. The plan does not change sidewalk widths, and would allow for some parking and loading in some places along Polk. However parking on Polk Street itself would be reduced significantly, especially with other features part of the plan including bulb outs and longer "daylighting" red zones near intersections.

The diagrams for Upper Polk are as follows:
  • Polk Street Midblock: CYCLE TRACK
    • With parking and loading zones
    • With bus stop 
  • Polk Street Street Intersections: CYCLE TRACK
    • With right turn to one-way street
    • With left turn to one-way street
    • With no designated turn lanes for low traffic two-way cross streets

In all scenarios it is assumed that curbs will not be moved per the SFMTA study. Polk Street is 69.5 68.75 feet wide and north of Geary or Post, it is 44.75 feet from curb to curb. South of here it is four feet wider, coming to 48.75 feet wide between curbs. Most of the debate has surrounded the northern part of Polk Street, also known as "Upper Polk".
Polk Street: CYCLE TRACKS mid-block with parking or a loading zone. Image: Urban Life Signs using Streetmix
With midblock parking on one side, which could also have some loading spaces, some parking is preserved (see above). Likewise, if placing bus stops at corners is too constrained at some intersections, especially when many left or right turn traffic exists, then mid-block bus stops should be considered. Note that the cycle track passes between the bus shelter and the sidewalk (see below).
Polk Street: CYCLE TRACKS mid-block with bus stop. Image: Urban Life Signs using Streetmix
Polk Street: CYCLE TRACKS corner intersections with right turn. Image: Urban Life Signs using Streetmix
Where right turns occur at one-way street, the cycle track would become a more classic bike lane to make it clear to both bikers and drivers that the two will be crossing eachothers' paths (see above). Where left turns are required, the bike lane in the same direction as the left turn could remain separated with a raised buffer if the street intersected is one-way.
Polk Street: CYCLE TRACKS corner intersections with left turn. Image: Urban Life Signs using Streetmix

Polk Street: CYCLE TRACKS corner intersections for a low traffic two-direction cross street. Image: Urban Life Signs using Streetmix
Finally, several intersections along Polk have low-traffic two-way streets (e.g. Vallejo and Polk). Here vehicles will be turning both left and right. However, dedicated turn lanes are not required for either direction, but a wider lane should be made approaching the intersection so that when cars do try to turn, there's enough room for a through car to pass. The design is similar to Valencia Street's redesigned intersections on lower traffic streets (e.g. 17th St and Valencia).

As mentioned earlier, all of this change would reduce the amount of on-street parking on Polk. According to the SFMTA, in 2012 or 2013 between Post and Union Street (Upper Polk), there are 240 on-street spaces, 1,300 on-street spaces in the area (going one block to the east and west), and 2000 spaces overall when the Polk Parking Garage is included. That means Polk Street only comprises 18% of on-street spaces, and 10% of overall spaces, and this does not even could private spaces used by the public (e.g. Walgreens, Lombardi Sports).

Polk Street at Pine. Image: 
To establish how many spaces would remain under the cycle track plan I've proposed, I took a quick scan of existing parking configurations on Polk Street between Post and Union. Red curb lengthening (aka "daylighting) extensions and corner bulbouts will remove about one or two spaces near each intersection. What remains, apart form mid-block bus stops, could stay as parking on one side.

By my rough estimation, approximately 80 spaces would remain. That's a 66% reduction of Polk Street on-street spaces from the 240 current spaces. Area on-street spaces would be 13%, and public area parking spaces (including parking garage) would be reduced by 8%. I'll let the numbers speak for themselves and just say that this idea should have been considered much more seriously.


  1. A reliable source (SF Cityscape) has informed me that streets north of Market, including Polk Street are 68' 9" wide from lot line to lot line. That means my width of 69' 6" is 9" (0.75 feet) off.

    All of the curb-to-curb widths are accurate and have been checked with 2 sources.

    So where to shave off the 4.5" on each side of the street? The sidewalks sadly. I'll update the designs in due time.

    1. The width of Polk is 68' 9" wide.
      Sidewalks currently on the corridor are 12'.
      What one could do is a 6' bike lane in both directions plus a 1' buffer, with parking (7') on one side depending on where the most deliveries occur. You would still be able to have 11' travel lanes (minimum, to accommodate Muni).

  2. Great point. I wonder if we could still push the MTA to reconsider.

    Here is a concept with a 2-way cycletrack (instead of separated, one-way cycletracks):

    Midblock (with parking):

    At intersection with bus stop on cycletrack side:

    At intersection with bus stop on parking side:

    The above use a total right-of-way width of 68'9" and a curb-to-curb distance of 44'9", as exists north of Post St.

  3. teo,

    Love your 2-way cycletrack proposal. It may even be better than one-way cycle tracks on each side.

    I'm no cycle track expert, but I'm sure both of them come with pros and cons. From what I can see, the sticky point is always the intersections where folks are passing across eachothers' paths like right turning cars/straight going bikes. This is the case with both ideas.

    Stay tuned, I've done a more comprehensive parking analysis that should better show what would be lost parking-wise.

  4. Hello,
    my name is Ana isabel, I'm an architect and a researcher at grupo Indisciplinar, from Belo Horizonte, Brazil.
    I'm writing my masters dissertation on open source urbanism and digital tools for civic participation and collaborative design and space production. One of the tools I approach on my work is StreetMix.
    I can see you used the tool for the Polk Street simulations, and it would be great if I could hear from you about the outcomes of the experience and if you used it in different occasions.
    I also hope you had good luck with the struggle concerning Polk Street.
    Best regards,

    1. Ana Isabel,
      Thanks for your interest in my article and the use of StreetMix. How about you write to my e-mail, brianstokle at urbanlifesigns dot com. You can ask me more specific questions and I can provide you with a more detailed response than in the comments section here.


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