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.