23 CFR 652.3 - Definitions.
(a) Bicycle. A vehicle having two tandem wheels, propelled solely by human power, upon which any person or persons may ride.
(b) Bikeway. Any road, path, or way which in some manner is specifically designated as being open to bicycle travel, regardless of whether such facilities are designated for the exclusive use of bicycles or are to be shared with other transportation modes.
(c) Bicycle path (bike path). A bikeway physically separated from motorized vehicular traffic by an open space or barrier and either within the highway right-of-way or within an independent right-of-way.
(d) Bicycle lane (bike lane). A portion of a roadway which has been designated by striping, signing and pavement markings for the preferential or exclusive use of bicyclists.
(e) Bicycle route (bike route). A segment of a system of bikeways designated by the jurisdiction having authority with appropriate directional and informational markers, with or without a specific bicycle route number.
(f) Shared roadway. Any roadway upon which a bicycle lane is not designated and which may be legally used by bicycles regardless of whether such facility is specifically designated as a bikeway.
(g) Pedestrian walkway or walkway. A continuous way designated for pedestrians and separated from the through lanes for motor vehicles by space or barrier.
(h) Highway construction project. A project financed in whole or in part with Federal-aid or Federal funds for the construction, reconstruction or improvement of a highway or portions thereof, including bridges and tunnels.
(i) Independent bicycle construction project (independent bicycle project). A project designation used to distinguish a bicycle facility constructed independently and primarily for use by bicyclists from an improvement included as an incidental part of a highway construction project.
(j) Independent pedestrian walkway construction project (independent walkway project). A project designation used to distinguish a walkway constructed independently and solely as a pedestrian walkway project from a pedestrian improvement included as an incidental part of a highway construction project.
(k) Incidental bicycle or pedestrian walkway construction project (incidental feature). One constructed as an incidental part of a highway construction project.
(l) Nonconstruction bicycle project. A bicycle project not involving physical construction which enhances the safe use of bicycles for transportation purposes.
(m) Snowmobile. A motorized vehicle solely designed to operate on snow or ice.