Glossary of Acronyms and Terms
Definitions: From A to C
AASHTO Green Book – American Association of State Highway and Transportation Officials (AASHTO), published Policy on Geometric Design of Highways and Streets. The Green Book is currently in its 5th Edition. Click here to jump to the AASHTO Bookstore to order a current copy of the the AASHTO Green Book .
Access Management: Involves providing (or managing) access to land development while simultaneously preserving the flow of traffic on the surrounding road system in terms of safety, capacity, and speed.
Advisory Committee: A representative group of stakeholders meeting regularly to discuss issues, have their comments and points of view recorded for later review, and seek consensus over project issues. Purpose: Provides a forum for stakeholders to regularly express their opinion on project issues and direction in a collaborative environment; for stakeholders to work together to reach consensus on project issues; and for the project team to monitor community reactions to project activities.
Advisory Signing – Signs that warn drivers of potential hazards.
Aesthetics – Consideration and/or evaluation of the sensory quality of resources (e.g. sight & sound).
Americans With Disabilities Act (ADA) – A federal law that was enacted in 1990 for the purpose of ensuring that all Americans have the same basic rights of access to services and facilities. The ADA prohibits discrimination on the basis of disability. To effect this prohibition, the statute required certain designated federal agencies to develop implementing regulations.
Arterial – Functional classification for a street or highway that provides the highest level of service at the greatest speed for the longest uninterrupted distance, with some degree of access control.
Average Daily Traffic - The average 24-hour volume, being the total volume during a stated period divided by the number of days in that period, normally a year or the number of days the road is actually open to public travel.
Brainstorming: A meeting or session that involves open discussion amongst a group of people. Purpose: Brainstorming sessions, often used to resolve conflicts, are intended to produce as wide a variety of ideas as possible. Ground rules for brainstorming sessions include: encourage all ideas; keep discussion of ideas to a minimum; generate as many unique ideas as practical; build on ideas of others; record ideas as they are offered (transcript, flip chart, online presentation, etc.) See: Free-Wheeling and Round Robin, two brainstorming techniques.
Capacity – The maximum number of vehicles which has a reasonable expectation of passing over a given section of lane or roadway during a given time period under prevailing roadway and traffic conditions.
Categorical Exclusion (CE or CATEX) –Under the National Environmental Policy Act, a CATEX is an action that normally does not require the preparation of an Environmental Assessment or an Environmental Impact Statement.
Centerline – (1) For a two-lane road, the centerline is the middle of the traveled way; and for a divided road, the centerline may be the center of the median. For a divided road with independent roadways, each roadway has its own centerline. (2) The defined and surveyed line shown on the plans from which road construction is controlled.
Charette: A meeting format used to define issues, analyze problems and alternative solutions and to reach consensus on the approach to be taken. Purpose: Resolve a problem or issue within a specific time period and when a range of solution options are required; define values and expectations.
Choker – Permanent structures that cause roadway to narrow, used for traffic calming.
Clear Zone – Area that extends beyond the right-or-way of a freeway and is clear of any structures or elements that may potentially be struck if a car leaves the freeway. The extent of the clear zone depends on several factors, such as the design speed or slopes.
Collaborative Task Force: a group assigned a specific task, with a time limit for reaching a conclusion and resolving a difficult issue, subject to ratification by official decision-makers. Its membership usually involves local people or representatives from interest groups, appointed by elected officials or agency executives. Purpose: Helps solve a specific problem, working strenuously toward consensus and presenting a strong and unified voice.
Collector - Functional classification for a street or highway that provides a less highly developed level of service than an Arterial, at a lower speed for shorter distances by collecting traffic from local roads and connecting them with arterials.
Community – While a community may be defined based on proximity to a project, or city, county, or neighborhood delineations; a broader definition acknowledges that a community may be based on common characteristics or interests, such as religion, ethnicity, income strata or concern for the economic viability of a region.
Community Impact Assessment (CIA) - The process that evaluates the potential impacts of proposed transportation projects on a local community and its sub-populations throughout the transportation decision-making process. The goal of CIA is to focus on the quality of life of the community.
Corner Radius – The radius of a circle used to fillet the curb line at an intersection.
Corridor Continuity - The overall coordination and sequence of visual features, as experienced by the roadway user (WSDOT, 2005).
CORSIM – a comprehensive microscopic traffic simulation, applicable to surface streets, freeways, and integrated networks with a complete selection of control devices (i.e., stop/yield sign, traffic signals, and ramp metering). It simulates traffic and traffic control systems using commonly accepted vehicle and driver behavior models. (FHWA). Additional information about CORSIM can be found online at: http://ops.fhwa.dot.gov/trafficanalysistools/corsim.htm
Critical Length of Grade – That combination of gradient and length of grade which will cause a designated vehicle to operate at some predetermined minimum speed. A lower speed than this is unacceptable and usually requires that an auxiliary climbing lane be provided for slow-moving vehicles.
Cross Section – The transverse profile of a road showing horizontal and vertical dimensions.
Culvert – Any structure under the roadway with a clear opening of 20 feet or less measured along the center of the roadway.
Curve Widening – The widening of the traveled way on sharp curves to compensate for the fact that the rear wheels of a vehicle do not follow exactly in the track of the front wheels.
Curvilinear Alignment – A flowing alignment in which the majority of its length is composed of circular and spiral curves. Cut Section – That part of the roadway which, when constructed, is lower in elevation than the original ground.
