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Acceleration Lane - A paved auxiliary lane, including tapered areas, allowing vehicles to accelerate when entering the through-traffic lane of the roadway.
Access - Permission, liberty, or ability to enter, approach, or make use of a roadway.
Access Control - The condition where public authority fully or partially controls the right of abutting owners access to the highway right of way. Full control of access is exercised to give preference to through traffic by providing access connections with selected public roads only and by prohibiting crossings at grade or direct private driveway connections. Partial control of access is exercised to give preference to through traffic to a degree than in addition to access connections with selected public roads, there may be some crossings at grade and some private driveway connections. Uncontrolled access over a highway, street or road does not limit the number of points of ingress or egress, except through the exercise of control over the placement and the geometrics of connections a necessity for the safety of the traveling public.
Access Point - An intersection, driveway, or opening on the right-hand side of the roadway.
Access Road - A road that gives direct access to the land and premises on one or both sides.
Accident Rate - The number of accidents that occurs per million vehicle miles of travel.
ADT - see Average Daily Traffic
Alignment – A specifically defined path in which transportation facilities are constructed.
Allottee Land - Land owned by individual Gila River Indian Tribal members
Alternatives Analysis - A detailed study and assessment of the various options available for the purpose of selecting one for implementation. Ideally, all feasible alternatives will be investigated. An alternatives analysis is required if funds are sought from the Federal Transit Administration for capital-intensive major transportation projects.
Auxiliary Lane - An additional lane on a freeway to connect an on-ramp and an off-ramp.
Average Daily Traffic - The average number of vehicles that pass a specified point during a 24-hour period.
C
CANAMEX - An international trade route, which will link Mexico, the United States and Canada.
Centerline - A line that is equidistant from the sides of a roadway. The centerline is typically the horizontal alignment of a road.
Channelization - The separation or regulation of conflicting traffic movements into definite paths of travel by use of pavement markings, raised islands, or other means.
Clear Zone - The total roadside border area, starting at the edge of the traveled way, available for safe use by errant vehicles. This area may consist of a shoulder, a recoverable slope, a non-recoverable slope and/or a clear run-out area. The desired width is dependent upon the traffic volumes and speeds and on the roadside geometry.
Clearance - Lateral distance from edge of traveled way to a roadside object or feature.
CLR - Corridor Location Report
Corridor - A broad geographical band that follows a general directional flow or connects major sources of trips.
Corridor Alternative - A broad geographical band in which high-level environmental studies and transportation analysis are conducted for the purposes of narrowing project alternatives and limits.
Cross Section - A representation of a road if cut off at a right angle to its centerline.
Crossroad - A road crossing a freeway, highway or other facility. It is typically the road carrying lesser traffic.
D
Deceleration Lane - A paved auxiliary lane, including tapered areas, allowing vehicles leaving the through-traffic lane of the roadway to decelerate.
Decision Sight Distance - Sight distance allowing for additional decision time in cases of complex conditions.
Design Concept Report (DCR) – A report produced to document criteria necessary to design improvements, identify available data, address alternatives, and recommend a solution. Once the DCR is approved, the development effort will proceed without further consideration of alternatives.
Design Criteria - Standards on which a judgment or decision about the roadway geometry may be based.
E
EA - See Environmental Assessment
EIS - See Environmental Impact Statement
Easement - A right acquired by one party to use or control property belonging to another party for a designated purpose, such as public utilities, streets or highways, transit lines.
Effect - There are two types of effect, direct and indirect.
- A direct effect (also known as a 'direct impact') is caused by the action and occurs at the same time and place.
- An indirect effect (also known as an 'indirect impact' or 'secondary effect') is caused by the action and occurs later in time or farther removed in distance, but is still reasonably foreseeable. Indirect effects may include growth inducing effects and other effects related to induced changes in the pattern of land use, population density or growth rate, and related effects on air and water and other natural systems, including ecosystems.
Environmental Assessment (EA) - An environmental study used under the National Environmental Policy Act of 1969 to determine whether an environmental impact statement is required.
Environmental Impact Analysis - The analysis of environmental (including human) effects that would result from the implementation of a project's alternatives in conformance with the National Environmental Policy Act.
Environmental Impact Statement - The National Environmental Policy Act of 1969 requires that federal agencies prepare detailed analyses of any of their actions that significantly affect the quality of the environment. Environmental impact statements (EIS's) are the result of this requirement.
EO - Environmental Overview.
Evaluation Criteria - Standards on which a judgment or decision on the various alternatives may be based.
Expressway - A divided arterial highway for through traffic. An expressway has full or partial control of access and generally has grade separations at major intersections.
External to External Trip - A trip that has both its origin and destination outside the study area but that involves travel through the study area.
External to Internal Trip - A trip that has either its origin or destination inside the study area.
F
Freeway - A divided highway for through traffic that has full access control and grade separations at all intersections; an expressway with full access control.
Frontage Road - A local street or road auxiliary to and located on the side of a freeway , expressway, or arterial highway for service to abutting property and adjacent areas and for control of access to the freeway, expressway, or arterial highway; a road contiguous to and generally parallel to an expressway , freeway, parkway, or through street. It is designed to intercept, collect and distribute traffic desiring to cross, enter, or leave such a highway and to furnish access to property that otherwise would be isolated as a result of the controlled-access feature. It is sometimes called a service road.
G
Grade - Rise in elevation within a specified distance. As an example, a 1-percent grade is a 1-foot rise in elevation in 100 feet of distance (measured horizontally).
Grade Crossing - A crossing or intersection of highways, railroad tracks, other guideways, or pedestrian walks, or combinations of these at the same level or grade.
Grade Separation - A vertical separation of intersecting facilities (road, rail, etc.) by the provision of crossing structures; the crossing of two highways, or a railroad and a highway, at different elevations.
H
Harmful Group - A grouping of accidents that was based on the type of object impacted.
Highway, Street or Road - General terms denoting a public way for purposes of vehicular travel, including the entire area within the right of way.
Horizontal Alignment - A combination of tangents, horizontal curves and spirals which defines the horizontal location of a roadway.
I
Impact – See Effect.
Incident - Any occurrence on a roadway that impedes the normal flow of traffic.
Interchange - The system of interconnecting ramps between two or more intersecting travel ways (highways, transit guideways, etc.) that are grade separated.
Internal to Internal Trip - A trip that has both its origin and destination inside the study area.
Intersection - The point at which two or more roads meet or cross.
L
Land Use - The purpose for which land or the structure on the land is being used, for example, residential, commercial, or light industry.
Level of Service - A qualitative rating of the effectiveness of a highway or highway facility in serving traffic, in terms of operating conditions (speed, travel time, comfort, convenience, traffic interruptions, freedom to maneuver). The Highway Capacity Manual identifies operating conditions ranging from A, for best operations (low volume, high speed) to F, for worst conditions.
Local Jurisdiction - The limits or territory within which the local government's authority may be exercised.
M
Mainline - The primary through roadway as distinct from ramps, auxiliary lanes, and collector-distributor roads.
Median - The portion of a divided highway separating traffic traveling in opposite directions.
N
National Environmental Policy Act (NEPA) - The National Environmental Policy Act of 1969 (NEPA) is considered to be the basic "National Charter" for protection of the environment. NEPA requires that, to the extent possible, the policies, regulations, and laws of the Federal Government be interpreted and administered in accordance with the protection goals of the law. It also requires Federal agencies to use an interdisciplinary approach in planning and decision making for actions that impact the environment. Finally, NEPA requires the preparation of an EIS on all major Federal actions significantly affecting the human environment.
No-Build Alternative - A planning option of leaving the situation as it already exists. Existing facilities and services are maintained, and existing transportation policies are continued.
Notice of Intent (NOI) – A notice that is prepared to inform the public that an Environmental Impact Statement will be prepared for a project.
O
OHV - Off-Highway Vehicle
P
Passing Sight Distance - The length of roadway ahead required to pass another vehicle without meeting an oncoming vehicle.
Purpose and Need - Explanation of why the federal agency and project proponent are undertaking the proposed action and what objectives they intend to achieve. Basis may include: capacity and transportation demand, safety, legislative directive, economic development/planned growth, modal interrelationships, system linkage and roadway deficiencies. The statement of purpose and need provides the basis for developing a range of reasonable alternatives and, ultimately, the identification of the preferred alternative.
R
Record of Decision (ROD) - A public document signed by the decision maker at the time of a decision. The ROD states the decision, alternatives considered, the environmentally preferable alternative or alternatives, factors considered in the agencies decision, mitigation measures that will be implemented, and a description of any applicable enforcement and monitoring programs.
Recoverable Slope - A slope on which a motorist may, to a greater or lesser extent, retain or regain control of a vehicle. Slopes flatter than 1(vertical) to 4 (horizontal) are generally considered recoverable.
Right of Way - A general term denoting land, property, or interest therein, usually in a strip, acquired for or devoted to transportation purposes.
Road - see "Highway, Street or Road"
Rural Areas - Those areas outside the boundaries of urban areas.
Rural Freeway - A freeway of which the alignment and cross-sectional elements are more generous in design, which is commensurate with a higher design speed and generally with greater availability of right of way.
S
Safety - The condition of being safe from undergoing or causing hurt, injury or loss.
Scoping Process - A process that allows for early identification of potentially significant environmental issues. This process begins with an introduction to the environmental review agencies and the public, the purpose of which is to initiate coordination and involvement activities that will span the life of the project. Agencies with specialized knowledge of these areas may be asked to participate as cooperating agencies, while other agencies are required by law to participate in project development.
Section 4(f) Property - Any publicly owned public parks, recreation areas, wildlife or waterfowl refuges, or any publicly or privately owned historic sites.
Service Interchange - A grade-separated interchange between a major highway or freeway facility and a crossroad.
Shy Distance - The distance from the edge of the traveled way beyond which a roadside object will not be perceived as an obstacle by the typical driver to the extent that the driver will change the vehicle's placement or speed.
State Jurisdiction - The limits or territory within which the State's authority may be exercised.
State Route - A highway owned and maintained by the State.
Stopping Sight Distance - The distance that allows a driver traveling at the maximum speed to stop before hitting an observed object.
Street - see "Highway, Street or Road"
Superelevation - The slope (in ft/ft) across the surface of the roadway, perpendicular to the centerline of the roadway.
System Interchange - An interchange between two major highway or freeway facilities where all of the movements are maintained without stopping or delays.
T
Taper Area - An area characterized by a reduction or increase in pavement width to direct traffic.
Typical Section - A cross section that is representative of the roadway design throughout the project area.
U
Urban Areas - Places within boundaries set by the responsible State and local officials having a population of 5,000 or more.
Urban Freeway - A freeway, located in an urban area, which is capable of carrying high traffic volumes and generally characterized by lower design speeds and lesser availability of right of way.
Urban Fringe Areas - Areas that act as a "transitional" segment between urban and rural settings.
V
Vehicle Miles of Travel (VMT) - A measurement of the total miles traveled by all vehicles in the area for a specified time period. It is calculated by the number of vehicles times the miles traveled in a given area or on a given highway during the time period.
Vertical Alignment - A combination of tangent grades and vertical curves which defines the vertical location of a roadway.
Volume - In transportation, the number of units (passengers or vehicles) that pass a point on a transportation facility during a specified interval of time, usually 1 hour.
W
Warrants - The criteria by which the need for a safety treatment or improvement can be determined.
Weaving - The crossing of two or more traffic streams traveling in the same direction along a significant length of highway, without the aid of traffic control devices (except for guide signs).
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