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.

Interstate 80. Credit: Paul Daniel Marriott