Originally Posted by
FBinNY
I'm surprised by the question, so let's turn it around for a moment. Is there any evidence that drivers know what sharrows mean? Even as a cyclist who's been active for 50+ years, very involved in advocacy for decades before I stopped, and should be tuned in, even I'm not sure what they mean. Yes, it's about shared road use, but do they mean a specific lane, or part of the road? Are we to ONLY ride in the marked area? What about in advance of a left? How do they change shared road use? Are they placed on roads deemed preferred for cyclists? Or, are they placed on roads with history of problems?
Shared lane markings did undergo an extensive experimental evaluation process before national adoption.
The San Francisco study was one of the more extensive evaluations,
and SLMs were also tested in other cities as well. A human factors survey was conducted as part of the SFO study to assess bicyclist and motor vehicle comprehension of the tested markings. Some cities did engage in education campaigns when SLMs were installed, but not all did so.