Originally Posted by
CliffordK
White plastic posts provide a visual barrier, but not a physical barrier.
Jersey barriers provide a physical barrier.
An uninhibited road shoulder provides some level of buffer for motor vehicles. In the case of the occasional cyclist, the white painted line probably serves everyone best. The more cars and bikes, the greater the barrier that is needed.
The most dangerous place is at intersections, and good visibility is needed for all, as well as considering turning traffic.
White plastic posts that are only even a visual barrier are better than just a white painted line because the vast majority of motorists are not going to casually hit them just to encroach upon the area of a bike lane while they have no trouble at all doing that with just a white painted bike lane line. We have painted bike lanes on side streets where there is room to park cars on each side and for 2 vehicles to pass one another going opposite ways without having to stop and there the lines are just fine.
There are pictures here:
http://www.dot.ca.gov/hq/oppd/dib/dib89.pdf
of other bike lanes I like.