In my opinion, Arlington County did a great job with the SHARROWs since they appear frequently, are centered in the lane, and are accompanied by bicycles may use full lane signs. The lanes are too narrow to share laterally and the speeds cyclists can travel here make it necessary to maximize visibility in the center of the lane. The signs and lane markings should decrease harassment and give cyclists some additional confidence to ride among traffic. In the past two years, Arlington County has put in SHARROWs in several other locations that are also well designed.
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For people unfamiliar with Arlington County, there are few north-south connectors since the county is divided by I-66 and Rte. 50 along with several lesser arterial roads. Promoting efficient and safe cycling on these north-south connectors is good for a robust transportation grid.