A recent study of sharrows yielded unsurprising (but nice to see) results:
The study was a before and after study collected videotape data of bicyclist interacting with motorists before and after the installation of the markings.
After the markings were placed, approximately 20 percent of the bicyclists rode over the shared lane marking, and another 10 percent avoided the marking when they approached. Thus, 30 percent tracked over or very near the shared lane marking.
The following differences between the before and after operational results were statistically significant:
- increase of about 10.5 inches between cyclists and parked vehicles
- increase in the portion of cyclists positioned near the center of the lane (before – 10%; after – 30%)
- decrease in the portion of cyclists positioned closer to parked cars than to the center of the lane (before – 71%; after 55%)
- increase in “weaving” between queued traffic and parked cars (before 10%; after 14%)
- decrease in in portion of cyclists positioned in empty parking spaces (before 29%; after 21%) (although parking occupancy rates were also different before and after)
- decrease in near-doorings (but the study includes a caveat about small sample sizes and the inability to control for this situation)
- the occurrence of cyclists yielding to motorists decreased, the occurrence of motorists yielding to cyclists increased
- approximately equal number of wrong-way cyclists in both periods (2%-3%)
- decrease in the percentage of cyclists on the sidewalk(before – 55%; after – 45%)
- increase in motorists following (rather than passing) cyclists (before – 16.5%; after – 22%)
- decrease in motorists passing (rather than following) cyclists (before – 34%; after – 28%)