Glossary of Terms
Alignment: the movement of a roadway through the landscape; its curves, straight sections and hills. Arterial: a roadway providing the principal high-volume and high-speed linkages within a community and between communities. Avenue: a broad urban thoroughfare, usually tree-lined. Boulevard: a broad urban thoroughfare, usually tree-lined and with a broad median. Clear zone: the recommended area alongside a roadway clear of all potential hazards (something an automobile might strike) such as trees, rocks, utility poles and the like. The recommended width of a clear zone varies based on the functional classification of the road. Collector: a roadway providing service between arterials and local roads. Design speed: the maximum safe speed at which a vehicle can be expected to operate on a roadway. The speed for which a roadway is designed: this may not be the posted speed. Designed landscape: a landscape, or the alteration or modification of the natural landscape that has been created specifically to provide a desired experience (usually aesthetic) to the user or a community. Designed landscapes are generally created by a landscape architect, planner, architect or other design professional. Drive: a park or leisure road, established in the nineteenth century, intended for pleasure driving. Errant vehicle: a vehicle leaving the roadway in a reckless or uncontrolled manner. Expectancy: a theory, based on a motorist’s “knowledge stores” of driving experiences, that suggests predictable driver responses to familiar situations and settings. Routine experiences, such as sufficient merging space at the end of a freeway ramp, become unconsciously established in the driver’s mind – thus creating conflict should the “expectancy” not be met. Galvanized steel: a zinc coating applied to steel to prevent rusting. Galvanized steel has a flat, chalky-gray appearance. Guardrail: a barrier, usually of a post-and-beam construction, located alongside a roadway, in medians and in front of hazards to prevent an errant vehicle from striking an obstacle or encountering a dangerous slope or drop-off. Horizontal alignment: the movement of a roadway to the left or right; its curves. Integrity: the current quality of a feature or element when compared to its original quality. Jersey barrier: an angled concrete barrier designed to guide an errant vehicle back to the roadway and guard against hazards. Lane: a narrow passage (or road) defined by buildings, hedges or fences. Liability: an obligation to perform a specific duty. Limited access: a concept whereby the entrances and exits of a roadway are restricted to certain locations: generally to allow for higher speed traffic movement due to the absence of cross streets and intersections. Local road: a roadway serving adjacent residences and businesses – generally of low-volume traffic. Median: a central space, often planted, dividing opposite moving travel lanes. National Register of Historic Places: a national listing of sites meeting the US Secretary of the Interior’s standards, maintained by the National Park Service. Neat line: an imaginary line representing the average face of an irregular surface, such as a stone wall. Park road: a road through a park. A park road is an element within a park. Parkway: a roadway contiguous with or linking park spaces. In its truest definition, a parkway provides access to recreational, scenic or leisure spaces. Post and cable guardrail: a guardrail constructed of regularly spaced posts connected by a flexible (usually steel) cable. Posted speed: the speed at which a roadway is signed. This is usually, though not always, lower than the design speed. Realignment: the repositioning of a segment of a roadway. Reinforced concrete: concrete with a steel reinforcing framework. Reinforcing enables the concrete to perform in structural situations. Concrete by its nature resists high compressive loads (the heavy weight of a truck, for example). Steel reinforcing resists high-tensile loads (the pull to the left or right one would encounter on a bridge, for example). Right-of-way: the land area dedicated to or associated with a roadway that is owned or managed by the road management entity: including the roadway, shoulder and affiliated landscape. Road: a long-distance overland route, typically linking different towns or commercial centers. Shoulder: a stabilized level area adjacent and parallel to the roadway that provides a recovery space for an errant vehicle or a safe space for a disabled vehicle. Sight distance: the length of roadway ahead that is visible to the motorist. Standards: the legally adopted policies and practices directing the design and construction of a road. Street: an urban thoroughfare, usually defined by buildings. Superelevation: the banking or sloping of a road curve to enable vehicles to maintain a speed consistent with the overall speed of the roadway. The banked ends of racing tracks represent an exaggerated superelevation. Taking: in legal terms, the direct acquisition of property, or the implementation of policies or actions that significantly impact a property. Tort liability: a situation in which an injury or harm has occurred, due to a breach of a preexisting duty or obligation, resulting in potential exposure to an individual or organization for damages. Vertical alignment: the movement of a roadway up and down; its hills. Volume: the number of vehicles a roadway carries.