A bike lane is an on-street facility for bicycles, designated by visual separation (a painted line).

Example of a bike lane. When next to fast traffic, at least 5 feet of clear biking space should be provided, with a preferable 6 or 7 feet.

 
Color adds distinction to a bike lane- and also slows down cars. All it took for a makeover on this street was some paint. Note where the old lines use to be (Sandnes, Norway).

 
This bike lane (in England) has a signal for the cyclists.

 
Here is a bike lane near Cambridge, MA. A sudden car door opening can put the cyclist in trouble.

 
Unmaintained bike lanes are ineffective. This one in Missoula, because of the slush, forces a cylist to ride in the blind-spot of motor vehicles.

 
A community is faced with tradeoffs in accommodating all modes of transportation. Slimmer lane widths for cars, bikes, and pedestrians can prevent the need to tear down buildings and vegetation- but may compromise safety. (near Stavanger, Norway)

 
As this biklane heads to the right, a 'slip', in the shape of a triangle, appears for left turning cyclists.

 

Links:

In:

Seattle Master Bicycle Plan - Seattle Times Newspaper Article

Out:
www.policy.rutgers.edu/papers/
a great piece of research on cycling

www.bikesbelong.org
'putting more people on bicycles more often through the implementation of TEA-21'

www.bta4bikes.org
Bicycle Transportation Alliance in Portland, Oregon

www.ibike.org
International Bicycle Fund

www.velo.qc.ca
VÈlo QuÈbec

www.bikeplan.com
Tracy/Williams bike/ped consulting (Missoula, MT)