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Terms that are in use on this site.

There are 111 entries in this glossary.
All A B C D E F G H I L M O P R S T V W Z
Term Definition

Programs designed to encourage and enable children to safely walk and bike to school. These programs often include education, encouragement and enforcement efforts in conjunction with a variety of site-specific engineering measures designed to improve safety for bicycling and walking.  See www.saferoutesinfo.org and http://safety.fhwa.dot.gov/saferoutes/ for more information.


The distance between a building and the property line or other buildings.


A wide outside/curb or shared lane (WCL) is the lane nearest the curb and is wider than a standard (12-foot) lane, providing additional space so that the lane may be shared more comfortably by motor vehicles and bicycles.  These lanes should be about 14 feet wide, as lanes wider than 15 feet can encourage the operation of two motor vehicles side by side.  If lanes become too wide, some motorists may also assume parallel parking is allowed, constricting the travel lane for bikes.


A roadway that is open to both bicycle and motor vehicle travel - may be an existing roadway, street with wide curb/outside lanes, or road with paved shoulders. Shared roadways typically have no bikeway designation, but should be designed and constructed under the assumption that they will be used by bicyclists.  Lanes are typically 12 feet wide or less, allowing cars to safely pass bicyclists only by crossing the center line or moving into another traffic lane.


The portion of the roadway to the right of the rightmost travel lane, excluding curbs, buffers, and sidewalks; shoulders can be paved, gravel, dirt, or grass, and serve a number of different purposes, (bicycle and pedestrian travel, structural roadway support, space for emergency vehicles to pass, stopped/disabled vehicle pull-off, space for vehicles to slow and turn right) typically dictated by their width and composition.


A type of multi-use path running adjacent and parallel to a roadway, like an extra wide sidewalk.  Sidepaths have special design challenges, as motor vehicles may not expect bikes to be entering an intersection from outside the travel lanes.  AASHTO discourages two-way paths located immediately adjacent to roadways due to the operational and safety issues that can occur.  Sidepaths should not be considered a substitute for street improvements even when the path is located adjacent to a highway, as many bicyclists find these paths less convenient than on-street facilities, particularly for utilitarian trips.


The distance a driver is able to see ahead; adequate sight distance is important to give drivers time to perceive and react to hazards or prepare to make decisions and maneuvers.


A shared roadway that has been designated with signing as a preferred route for bicycle use to provide continuity to other bicycle facilities, or to designate preferred routes through high-demand corridors.


Water that runs off impervious surfaces (e.g. rooftops, pavement) during or after precipitation, car washing, over-watering laws, etc.


Fixtures installed along the roadway, at or above grade level, including lamp posts, pedestrian lighting, fire hydrants, street signs, benches, trash cans, bike racks, newspaper boxes, water fountains, and planters.


The elements within and along the street right-of-way that define its appearance, identity, and functionality, including adjacent buildings and land uses, street furniture, landscaping, trees, sidewalks, and pavement treatments, among others.


Using the actual crash performance of geometric design choices, instead of relying solely on design standards, to evaluate safety.

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