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Clark Street buffered bike lane just north of Diversey Avenue. Photo by Adam Herstein. 

CDOT responded today to my inquiry asking why Clark Street between Diversey Avenue and Addison Avenue received a buffered bike lane and not a protected bike lane. Bikeways planner Mike Amsden writes:

Clark Street (Diversey to Addison) was striped as a buffer protected bike lane, and not a parking protected bike lane, because it is a 51′ roadway throughout the project limits. As you might know, the minimum roadway width for installing barrier protected bike lanes on roadways with one travel lane and one parking lane in each direction is 52′, and the preferred minimum width is 58′. A 52′ roadway allows for a 5′ bike lane, a 3′ buffer zone, an 8′ parking lane and a 10′ travel lane in each direction. However, even when a roadway is 52′, other roadway characteristics and operational considerations must be assessed before installing parking protected bike lanes. These characteristics include the amount of bus, truck and bicycle traffic, loading and delivery needs of local businesses, emergency vehicle access and maintenance requirements.

These standards come from the NACTO* Urban Bikeway Design Guide. If you have not read this guide I recommend doing so as it will likely answer many other questions you may have. The guide can be found here. http://nacto.org/cities-for-cycling/design-guide/

To answer your final question, if we were to recommend a parking protected bike lane on a 51′ roadway, all curbside uses (parking, standing, loading, valet, etc.) would have to be eliminated on one side of the roadway for the entire stretch in order to do so.

1 foot is all it takes, it seems. You can see the relevant NACTO standard in this image. Notice items 4, 5, and 6, that describe the minimum widths for the bike lane, buffer area, and parking lane, respectively.

One-Way Protected Cycle Tracks

Design guidance for One-Way Protected Cycle Tracks in the NACTO Urban Bikeway Design Guide.

Update: Why can’t certain lanes be narrower?

Someone asked in the comments this question, which Amsden anticipated: “We can’t go with a 7′ parking lane because then you’d have a 7′ parking lane next to a 10′ travel lane. People wouldn’t be able to get out of their cars, buses/trucks wouldn’t be able to maneuver, emergency vehicle access would be restricted, etc. That’s why even a 52′ roadway (with a 8′ parking lane next to a 10′ travel lane) is considered really tight.”

* National Association of City Transportation Officials, the yin to American Association of State and Highway Transportation Officials yang (AASHTO).

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  • http://www.facebook.com/profile.php?id=1136058783 Eloise Mason

    I wonder why they insist on 10′ travel lanes? NACTO says nothing (in that image) about car lane widths, just bike and buffer. Even the widest passenger/commercial vehicles on the road aren’t much more than 6′ wide (though i admit I don’t know what CTA busses clock in at). Why not narrow the travel lanes by 6″ each and actually protect cyclists, instead of installing a worse-than-nothing, incredibly narrow ‘buffer’? I bet NACTO has rules on minimum buffer-striping widths, too, which are probably being ignored.

    Wider lanes encourage speeding, too, like Clark ever has a chance to get up to speed with all the traffic …

    • http://www.stevevance.net/ Steven Vance

      Buses are 8.5 feet wide. Notice in the NACTO guidelines that the combined width of the buffer area and parking lane must be 11 feet (8+3 feet).

    • Ryan Wallace

      10′ travel lane is actually very narrow by most standards. Most angencies consider 11′ as minimum and 12′ is standard. I appreciate that (it at least appears as though) effort was made to investigate protected lanes.

    • http://www.facebook.com/cameron.puetz Cameron Puetz

      Fire trucks are another key vehicle to consider in road design. The core of a fire truck, excluding mirrors, ladders, and other items mounted to the side of the truck, is about 8 ft. Those side protrusions probably add at least 6 in to either side bringing the total width to 9 ft or more.

  • Michael Cornfield

    So it seems from this, the next question is what would it take to get the metered parking spaces from at least one side of the street relocated?

    • http://www.stevevance.net/ Steven Vance

      A lot of money to “lease them back” or an equivalent number of unmetered spaces in other locations to make a swap.

      • http://www.bikewalklincolnpark.com/ Michelle Stenzel

        And those nearby spaces that could be newly converted to metered spaces can be anything from unused loading zones to zoned parking areas to completely unmetered, unzoned spots. There are plenty of those spots everywhere, if you start looking for them. Unfortunately, the opinions of business owners and nearby residents who may resist moving metered parking tend to hold more sway with locally elected officials than the people on bicycles, who are perceived to be “just passing through”.

        • http://www.stevevance.net/ Steven Vance

          I’m trying to maintain a list of studies that research how a person’s mode of transportation influences how often they visit businesses and how much they spend per visit. Bicyclists have been found to spend less per visit than people who arrive by other modes, but they visit more often.

          Isn’t the entire northbound parking lane from North Avenue to Armitage Avenue unmetered? There’s a start… John and I were out there today, showing a D.C.-based journalist just what transportation in Chicago is like.

          • http://www.bikewalklincolnpark.com/ Michelle Stenzel

            You mean on Clark, I presume? No, from LaSalle to Armitage it’s all metered. From North to LaSalle I think it’s all either no parking, loading zone for the museum, or bus zones. That entire stretch doesn’t need parking moved or removed to put in a PBL, it only needs to have a reduction in through lanes.

          • http://www.stevevance.net/ Steven Vance

            Yeah, on Clark. I was there at about 3 PM. Very few people have parked their cars on northbound Clark Street from LaSalle/North to Armitage. I guess it’s only useful during Green City Market…

        • nonya

          equivalent isn’t just in number of spaces, it’s in revenue as well. ie, the city can’t just remove a bunch of heavily used spaces on Clark through Lincoln Park and Lakeview and replace them with spaces at 13th and Damen by a railyard that nobody would use. There might also be a proximity requirement as well (not sure on that).

          • http://www.stevevance.net/ Steven Vance

            That’s right. The swap has to be revenue neutral or revenue positive (the new spaces could earn more). I’ve skimmed the entire contract and read some parts fully states that a swap can be made to an unmetered part that is projected to earn the same revenue based on formulas defined in the contract. (Aside: The entire contract looks to be written by the company that won the bid to lease the parking meters and own all the revenue.)

          • http://www.bikewalklincolnpark.com/ Michelle Stenzel

            As I understand it, a spot within the same ward’s boundaries is considered to be equivalent.

          • http://www.stevevance.net/ Steven Vance
  • http://blog.theplannersdreamgonewrong.com jason tinkey

    So there’s 8 feet total going to the bike lane, which means there WOULD be enough width for a PBL under the street design guidelines which London uses. (2 meter lane + 0.5 meter buffer = 8 feet 3 inches)

    See http://www.tfl.gov.uk/assets/downloads/businessandpartners/lcds_chapter4.pdf

    • http://www.stevevance.net/ Steven Vance

      Seeing what TfL has done with the “cycle superhighways” and recent intersection treatments, I’m not sure I trust their judgment.

      • http://blog.theplannersdreamgonewrong.com jason tinkey

        Agreed about the superhighways, my point was that it’s a bit disheartening to hear CDOT is adhering so tightly to one set of “standards” (even if they are superior to AASHTO), when there are plenty of others around to choose from. A city with the size and dynamism of Chicago should be -setting- the standards.

        And I absolutely loathe the buffered lanes…if there’s no enforcement of double parking or lane violations they’re completely pointless.

  • http://stopandmove.blogspot.com/ Jass

    San Francisco and Boston both have 9.5 foot motor lanes, providing the necessary missing foot.

    • http://www.stevevance.net/ Steven Vance

      I updated the post to include something else CDOT’s Amsden said about the width of travel lanes.

      • http://stopandmove.blogspot.com/ Jass

        I see that but I dont buy that the extra foot makes a difference. The 9.5 foot lanes in Boston are on a major route with heavy bus and emergency traffic (near Boston Medical Center).

        Cut 3 inches from everything, and now youve got TOO MUCH space to work with.

  • J

    It seems a shame that these lanes couldn’t be protected. Can anyone tell the difference between 9.5 foot lanes and 10 foot lanes? It will sure as hell calm traffic, having only 19 feet of clear space between parked cars, forcing drivers to navigate carefully in a busy area. With the buffered setup, you have 35 feet of clear space between parked cars, allowing cars to bypass obstacles without slowing down too much. Is it really so bad to want people to drive slowly through a congested business district?

    Also, several sections of the Williamsburg Bridge in New York City use two 9 foot lanes, with barriers on both sides. It works just fine.
    http://goo.gl/maps/8RcFU

  • http://www.facebook.com/cameron.puetz Cameron Puetz

    Given the conflicts that a protected lane would create between cyclists and boarding/unloading bus passengers, on a heavy bus traffic street like Clark I don’t really see a buffered lane as a bad choice.

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