Monday, February 4, 2013


What exactly do sharrows denote? Specifically, do they signify anything legally? Or do they serve as more of a reminder to bikers and drivers that they ought to be sharing the road? Specifically, I'm wondering if they are intended to mean the entire lane upon which they are painted is meant to be shared by bikes and cars, or do they mean that just the width of the sharrow are shared space? I know that in SF, sharrows were deployed to mark shared lanes in an effort to keep bikers from getting doored. They tend to be painted much closer to the middle of the lane than the ones here in Ann Arbor. As you can see in this GoogleMaps picture, the sharrows here put you well within the range of the doors on parked cars:

So does anyone know what our local sharrows are supposed to communicate? Do they denote the shared portion of the lane, or that the entire lane is to be shared?

UPDATE: Homeless Dave just sent me a link to a document from the City's Transportation Department. From the paper:

Shared-use arrows, or sharrows, are pavement markings that designate a roadway for shared use between motor vehicles and bicycles. Figure A-2 shows the sharrow at Division and Liberty. They are a visual representation of what a motorist can expect from cyclists on the roadway, and they are used in a variety of circumstances. On narrow roads, sharrows alert motorists that the road is a bicycle facility despite the lack of bicycle lanes. In addition, where roads with bike lanes add a turning lane near intersections, bike lanes may be dropped due to the road width. In this situation, sharrows inform motorists that bicycles will continue using the road up to and through the intersection.

Prior to the Plan, the City had experimented with sharrow application on three roadways in the downtown area:
· S State St.
· E Liberty St.
· E William St.

The Plan designated sharrows as a solution for areas where, due the addition of automobile turning lanes, bike lanes end. Proposed Near-term in-road bicycle facilities in the Plan called for 5.7 miles of primary roads to be marked with sharrows.

So there you have it. I hope that makes things clearer.


  1. Ben, they are boost pads like in Mario Kart. That's why it makes that sound and speeds me up every time I ride over one.

    Do you never listen to me.

  2. I wish they'd be more careful with their language. Alerting motorists that a road is a bicycle facility leaves motorists free to assume that means other roads are not bicycle facilities.

  3. There is some research out there that indicates sharrows improve the spacing between bicyclists and cars (both parked and passing). They are like bike lanes without the lines and often get used when a roadway isn't quite wide enough to meet the requirements for striping.

  4. @Vos,

    I believe the research. I think they do serve as a good reminder to folks to share the road.

  5. Saw an amazing way of making bike lanes in Europe (I think it was in Amsterdam) on the documentary "Urbanized" where they have the bike lane between the street parking and the sidewalk. It was pretty much genius and awesome!