The separation distance between overtaking motor vehicle and bicycle is slightly less in a BL than in a WOL, even though a WOL is narrower overall. The ambiguity in a WOL may cause motorists to move over farther. With a BL, as long as the bicyclist is in her lane and the motorist in his, there is no need to move over. Motor vehicle speed . BLs narrow the motorists' travel area as compared to a WOL so may have a traffic calming effect.
BLs allow motorists to pass bicyclists without slowing down.
The ambiguity of a WOL induces motorist caution, thus slower speed. Motor Vehicle Encroachment . However, encroachments are not necessarily a bad thing. There is no evidence of motorist collisions due to bicyclist induced encroachments. Moreover, this finding is questionable.