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  1. #1
    -=Barry=- The Human Car's Avatar
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    Sharrow lane width recomendations

    One of the cool things about Sharrows is they can be used irregardless of lane width and the do something positive for biking. But it looks like the accompanying documentation does not specify the minimal lane width where the Sharrows will function well to create some extra space for cyclists.

    My observations is that on lanes 10' or less Sharrows encourage liner lane sharing and on 12' or more you get a fuzzy bike lane with sharrows. A problem has come up where the city might be changing lane widths from 10' inside and 12' outside to 11' for both lanes and sharrows and personally I would like to keep the 10' 12' combo and add sharrows to the 12' lane.

    So the question is; is there any official documentation where wider lanes work better with sharrows. And as always I would be interested in your thoughts on lane widths and sharrows.
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  2. #2
    totally louche Bekologist's Avatar
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    i dont think the idea of a sharrow is 'creating extra space' for bicyclists, barry. You want cyclists and motorists to share a 12' lane side by side?

    i believe sharrows will 'work' only on low speed 25-30 MPH, narrow laned roads with the sharrow centered in the lane, but that's my opinion.

    locally the discussion has been on how far centered in the lanes they are; here in Seattle there is some movement to use both super sized sharrows as well as 'standard' size sharrows further out from their current placements...

  3. #3
    Al noisebeam's Avatar
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    Quote Originally Posted by Bekologist View Post
    i dont think the idea of a sharrow is 'creating extra space' for bicyclists, barry. You want cyclists and motorists to share a 12' lane side by side?

    i believe sharrows will 'work' only on low speed 25-30 MPH, narrow laned roads with the sharrow centered in the lane, but that's my opinion.

    locally the discussion has been on how far centered in the lanes they are; here in Seattle there is some movement to use both super sized sharrows as well as 'standard' size sharrows further out from their current placements...
    Those are similar to my thoughts as well, although I don't see why those speed restrictions would be needed. I always assumed/expected sharrows were for lanes that tended to be more appropriate for front to back sharing vs. side by side sharing. Also having them closer to the center of the lane makes that clearer.

    Al

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    totally louche Bekologist's Avatar
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    regarding traffic flow, noisebeam, the general consensus is that at higher speed differentials, greater traffic seperation is desired for all sorts of reasons.


    this is widely accpeted in the transportation engineering community.


    Sharrows in the USA need to morph into unmistakeable signs to both drivers and bicyclists that bicyclists have FULL use of the lane.

  5. #5
    feros ferio John E's Avatar
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    I concur w/ Bekologist.
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  6. #6
    Al noisebeam's Avatar
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    Quote Originally Posted by Bekologist View Post
    regarding traffic flow, noisebeam, the general consensus is that at higher speed differentials, greater traffic seperation is desired for all sorts of reasons.


    this is widely accpeted in the transportation engineering community.


    Sharrows in the USA need to morph into unmistakeable signs to both drivers and bicyclists that bicyclists have FULL use of the lane.
    I still don't think they should only be used on low speed roads. There are many roads over 30mph that would benefit with easily implemented sharrows - roads that would unlikely be widened anytime soon. There are also roads that are over 30mph that would not benefit with traffic separation - for example roads with frequent intersections.

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  7. #7
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by Bekologist View Post
    Sharrows in the USA need to morph into unmistakeable signs to both drivers and bicyclists that bicyclists have FULL use of the lane.
    I think that is what SHARROWs are good at. Sending a signal that the cyclist can use the center -- or right-center -- of the lane. Probably most useful in the context that Al suggests -- promote front to back sharing -- unless the lane is particularly wide.

    I don't know whether SHARROWs actually help people who need it -- that is, will an inexperienced cyclist actually move further away from the curb over the arrow? -- but in the few places that I have seen them here and in Santa Fe, they do seem to provide a signal to drivers that "yes, HPVs are supposed to be here."

    Regarding width and placement on a narrow lane, roughly speaking, I would paint it 4-5 feet wide in a right-centerish position with no part of the arrow within 2-feet of the curb.

    EDIT: I guess the other advantage is that SHARROWs are presumably cheaper to implement and maintain.

  8. #8
    totally louche Bekologist's Avatar
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    sending the signal the cyclist should be in the right side of a narrow lane is not the message to be sent out about unshareable, substandard width lanes. off centered sharrows do not provide the message 'full use of lane'.

  9. #9
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by Bekologist View Post
    sending the signal the cyclist should be in the right side of a narrow lane is not the message to be sent out about unshareable, substandard width lanes. off centered sharrows do not provide the message 'full use of lane'.
    I don't know about that. Remember if the lane gets really narrow -- say ten feet -- and you can't use the two right-most feet of the lane, the five-foot-wide arrow is essentially going to be in the center. At nine feet, the arrow is dead center. At twelve feet -- assuming we follow the minimum standard outlined earlier -- the arrow still reaches the center. Roughly speaking, people slide further left for left-turns or extraordinary situations. Both of which are generally pretty easy to communicate.

    I write right-centerish since, anecdotally, you are not going to get inexperienced cyclists to ride there regardless of signage, special arrows, or diety intervention. An experienced cyclist will often slide over either by preference or necessity with or without the SHARROW.

  10. #10
    Al noisebeam's Avatar
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    Quote Originally Posted by Bekologist View Post
    sending the signal the cyclist should be in the right side of a narrow lane is not the message to be sent out about unshareable, substandard width lanes. off centered sharrows do not provide the message 'full use of lane'.
    Totally agree. It is one reason I prefer sharrows (in concept) over "Share The Road" signs when narrow lanes are present. The StR signs most often do not indicate that sharing may result in a centerish cyclist position.

    Al

  11. #11
    genec genec's Avatar
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    Quote Originally Posted by noisebeam View Post
    Totally agree. It is one reason I prefer sharrows (in concept) over "Share The Road" signs when narrow lanes are present. The StR signs most often do not indicate that sharing may result in a centerish cyclist position.

    Al
    Agreed, not to mention the misinterpretation of StR... "hey cyclist, move over... you're supposed to share..."

  12. #12
    Al noisebeam's Avatar
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    Quote Originally Posted by genec View Post
    Agreed, not to mention the misinterpretation of StR... "hey cyclist, move over... you're supposed to share..."
    Worse is that some share the road signs (namely the ones used in AZ) show the cyclist riding in the gutter. I'd rather not have this type of sign adjacent to roads with NOLs.

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  13. #13
    totally louche Bekologist's Avatar
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    i can't find any specific reference to recommended lane width for sharrows except for blanket statements like 'designed to be placed in lanes too narrow to be safely shared'.

    since these are experimental in the US in about a dozen cities so far, perhaps some forward thinking municipal planners have a developing standard? I'd cull Sheboygan and the other cities for any design recommendations.

  14. #14
    52-week commuter DCCommuter's Avatar
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    Around here (DC and Arlington, VA) sharrows are misused to create "back-door" bike lanes on roads that are too narrow for a bike lane. The sharrow is painted next to the gutter in 11' or narrower lanes. On North Harrison Street in Arlington they've even put a "bike lane" sign next to a lane painted that way.

    The DC DOT has a Bicycle Facility Design Guide (available at http://ddot.dc.gov/ddot/cwp/view,a,1245,q,640118.asp) that specifies the symbol be centered 4' from the curb without parking, 11' with parking -- even if that means putting it in the parking lane.


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  15. #15
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by noisebeam View Post
    Worse is that some share the road signs (namely the ones used in AZ) show the cyclist riding in the gutter. I'd rather not have this type of sign adjacent to roads with NOLs.

    Al

  16. #16
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by DCCommuter View Post
    Around here (DC and Arlington, VA) sharrows are misused to create "back-door" bike lanes on roads that are too narrow for a bike lane. The sharrow is painted next to the gutter in 11' or narrower lanes. On North Harrison Street in Arlington they've even put a "bike lane" sign next to a lane painted that way.
    Whew ... glad that someone else hates that SHARROW. I tried to show it to Barry from space that other week but could not view it.

  17. #17
    -=Barry=- The Human Car's Avatar
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    The design specs of sharrows is such that they are placed on the right side of the lane. As much as I or anyone else would like to see sharrows in the center lane position that really is not in the stars for this treatment in the near future. So IMHO any discussion about better positioning of sharrows in the lane is mute in this thread.

    So far I have not experienced any real significant negative influence of sharrows on "proper" VC style. What I have experienced is this type of "bike facility" on narrow lanes is not that effective in getting more people out on bikes (but it's still early in the season so who knows.)

    So what I am thinking is if sharrows are not performing well on narrow lanes to get more people out on bikes (and is not needed for the VC) so perhaps some other treatment might be preferred on narrow lanes or narrow lanes could be widened a bit.

    I will also note to my DC brethren that are concerned about side by side sharing in a 12' lane, DC law does not allow you to take the lane unless the lane is less then 12' wide.
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  18. #18
    totally louche Bekologist's Avatar
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    Why????

    super sized sharrows are being considered for Seattle streets, Barry. Sharrows ARE experimental in about 10(?) cities right now, perhaps Toole Design could help with more forward thinking sharrow placement, they are currently advising many US cities with bicycle master plans and are forward thinking transportation engineers....

    www.tooledesign.com

    and a DC requirement to always share lanes that are over 12 feet wide? I'd be ignoring that 'rule' left and right. aren't there exemptions for unsafe lane conditions, turning traffic, avoiding obstacles... most of these 'requirements' have multiple conditionals that allow cyclists full use of any traffic lane regardless of width.
    Last edited by Bekologist; 05-15-08 at 12:25 PM.

  19. #19
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by Bekologist View Post
    I'd be ignoring that 'rule' left and right.
    I forget the details ... I believe that there are the typical exemptions. But yes ... we ignore the rule often.

  20. #20
    totally louche Bekologist's Avatar
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    so let's see...lanes less that 12 feet wide, DC bicyclists are required to take a full lane? And sharrows are pretty much indicated only in lanes too narrow to be shared safely??

    Seems a very compelling reason to have sharrow placements moved to the left a few feet IMO, and now is the time to lobby for it!! in cities that are adopting MUTCD standards for sharrows.

    remember, too, municipalities are generally NOT liable for design standards in excess of MUTCD designations. or so I've read, let me search for that article...

  21. #21
    -=Barry=- The Human Car's Avatar
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    Quote Originally Posted by Bekologist View Post
    Why????

    super sized sharrows are being considered for Seattle streets, Barry. Sharrows ARE experimental in about 10(?) cities right now, perhaps Toole Design could help with more forward thinking sharrow placement, they are currently advising many US cities with bicycle master plans and are forward thinking transportation engineers....

    www.tooledesign.com

    and a DC requirement to always share lanes that are over 12 feet wide? I'd be ignoring that 'rule' left and right. aren't there exemptions for unsafe lane conditions, turning traffic, avoiding obstacles... most of these 'requirements' have multiple conditionals that allow cyclists full use of any traffic lane regardless of width.
    Sharrows are in the final stages of being adopted into the MUTCD which is why so many cities are adopting them because of the previous documented success and the assumed final adoption by the MUTCD. Baltimore has not applied to study different placement of sharrows so therefore cannot place them outside the original design specs and I assume the same thing for DC. Toole can only do so much if the city they are working with does not agree to do and fund all the extra things needed for a new experimental design they are stuck with what's available (even though the do push the envelope a bit.)

    Super Sized Sharrows are not regular sized sharrows which is why they are different.
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  22. #22
    Senior Member randya's Avatar
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    I have no idea what the MUTCD actually says about positioning of sharrows in the lane; however, for maximum effectiveness, sharrows should be placed in the middle of the lane, and not in the right tire track position, IMO.

  23. #23
    52-week commuter DCCommuter's Avatar
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    Quote Originally Posted by The Human Car View Post
    So what I am thinking is if sharrows are not performing well on narrow lanes to get more people out on bikes (and is not needed for the VC) so perhaps some other treatment might be preferred on narrow lanes or narrow lanes could be widened a bit.
    That "other treatment" would be sharrows in the middle of narrow lanes.

    Quote Originally Posted by The Human Car View Post
    I will also note to my DC brethren that are concerned about side by side sharing in a 12' lane, DC law does not allow you to take the lane unless the lane is less then 12' wide.
    That's not true. You can take the lane any time conditions make it unsafe to ride to the right, or when traveling at the prevailing speed. What the law says is that a lane 11' or less is presumed to be unsafe to ride right.

    What's interesting is the design guide does not show any examples of sharrows on lanes less than 12' wide. The presumption in the design guide is that cyclists will ride in the door zone when parking is present.
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  24. #24
    totally louche Bekologist's Avatar
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    I think the MUTCD will be adopting the guidelines that the edge of sharrows allow 2 and a half feet for the door zone in edge striped parking, minimum of 11 feet from edge of unstriped parking.

    The problem Seattle is running into is the 11 feet minimum. cars commonly park out past their expected footprints, leaving sharrows in the door zone.

    Barry, check out this legal opinion re: federal design mandates on communities.....

    http://www.planetizen.com/node/30681

    I see absolutely no compelling reason why a community could not redesign sharrows to be larger and centered in the lane as the design intent of sharrows is indicating cyclist road position in lanes too narrow to be safely shared, meaning, bikes should be riding center lane......

    it looks to be a flawed implementation, Barry, if sharrows are morphing into side of road designators in marginally wide lanes. Sharrows have the planned use for marking lanes too narrow to be safely shared on roads also too narrow to allow implementation of well designed bike lane infrastructure.

    in fact, the design mandate states they may be placed further than 11 feet from the curb, so there's even allowances to have sharrows centered in the lane!

    and noisebeam, sharrows will not be recommended on streets over 35 MPH. seems the traffic engineers still got some sense, eh!
    Last edited by Bekologist; 05-15-08 at 10:40 PM.

  25. #25
    -=Barry=- The Human Car's Avatar
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    Good points all.

    To DCCommuter: As long as you are aware that additional proof may be required in order to legally take the lane in a over 11' lane in DC.

    To Bek: All good points but what do you see the advantage of a centered positioned sharrow over a BMUFL sign (Bikes May Use Full Lane) or the standard share the road signs?

    For those of you who want to officially comment on Sharrows I'll direct you here: http://www.baltimorespokes.org/artic...80330163659675

    And getting back to my problem in more general terms what would be the best treatment for two travel lanes (same direction) with 22' of ROW with the right lane used as off peak parking and the speed limit is 35mph (major arterial.)
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