Effectively one way for cars, but not exclusively: they can turn around if need be, so it's not quite a contraflow bike lane (with the attendant safety issues). Less traffic than a two-way street, more flexible (for the block's residents, and for cyclists) than one-way. And no lost parking, since the curb extension wouldn't be parking anyways.
Little sleeve just for eastbound bicycles!
The neighbours, obviously adept at gardening, have lent this to the community.
Full-canopy residential byways make for a nicely shaded bike ride -- unlike wide, busy, tree-less arterials.
Do not enter -- except bicycles.
Bikes aren't tempted to use the sidewalk to go the "wrong way," which is safer for pedestrians.
Bicycles can enter via the cutout, but cars can only exit. It looks to
be quite popular at rush hour. At Yukon & 10th Streets in front of
City Hall in Vancouver, B.C. (Here's a close-up of what a "bike sleeve" like the one at right looks like,
and here's a nearby, raised example perhaps better suited to snowy areas.)