Glossary of Transportation Planning Terminology

  1. A-D
  2. E-I
  3. J-N
  4. O-Z
3-C Planning - Comprehensive, Cooperative and Continuous transportation planning process.

Aggregate Demand Model - A model obtained by combining travel observations for individuals into geographic zones.

Annual Average Daily Traffic (AADT) - Data used to represent the amount of traffic occurring on roads. AADT is collected annually for various segments of roadway by the road authority.

Access - Refers to the ability to reach or connect to a roadway.

Access Management - Techniques of transportation infrastructure management intended to: reduce congestion and accident rates, lessen need for highway widening, conserve energy, and reduce pollution. Examples include; limiting entrance and exit of traffic on highways, use of medians and turn lanes, placement and timing of signals, as well as implementation of supportive
local by-laws and policies.

  1. The extent to which facilities are barrier free and usable by disabled persons, including wheelchair users.
  2. A measure of the ability or ease of all people to travel among various origins and destinations.
  3. Ability to reach a destination or use a facility or service without being impeded by physical or other barriers due to auditory, visual, mobility, or cognitive disabilities.
Alternative Modes (of Transportation) - The term "mode" is used to refer to and distinguish from each other the various forms of transportation, such as automobile, transit, ship, bicycle and walking. Alternative mode refers to any mode other than single occupant vehicle.

Arterial - A major street or highway. It is a general term, which includes expressways, major and minor arterial streets' and provincial highways having regional continuity. It is a road intended to move a relatively large volume of traffic at medium to high speeds.

Attainment Area - An area with air quality that meets or exceeds the U. S Environmental Protection Agency (EPA) health standards as stated in the Clean Air Act. Non-attainment areas are areas considered not to have met these standards for designated pollutants. An area may be an attainment area for one pollutant and a non-attainment area for others.

Attraction - The pull of attracting power of a zone normally measured as a fraction of employment activity. For non-home based trips, attractions in a zone can be considered synonymous with trip destinations in that zone.

Authorization - The level of funding designated by Congress for specific legislation.

Auto Occupancy - The average number of people in a vehicle for a particular trip purpose. Used to convert person trips to vehicle trips.

Average Daily Traffic (ADT) - The average number of vehicles passing a specified point during a 24-hour period.

Base Fleet - The average number of transit revenue vehicles in scheduled operation during the non-peak hours of the average weekday operation.

Base Volume - The traffic existing on the network in the base year.

Block Number Areas (BNA) - Small statistical subdivisions of a country. They are used for grouping and numbering blocks in all countries and statistically equivalent entities without census tracts.

Bottleneck - The point of minimum capacity along a highway segment.

Bus - A self-propelled rubber tired vehicle designed to carry a substantial number of passengers, commonly operated on streets and highways.

Bus Trip - A bus trip is defined as a one way trip by a bus while in revenue service, starting at one end of a route and ending at another end of a route. A round trip is counted as two separate bus trips.

Capacity - The volume of vehicles the road was designed to carry in a unit of time, such as an hour; can also be applied to transit or bicycle/pedestrian paths.

Carbon Monoxide (CO) - A colorless, odor-less, tasteless gas formed in large part by incomplete combustion of fuel. Human activities (i.e., transportation or industrial processes) are largely the source for CO contamination.

Carpool - Any vehicle (usually a car) or arrangement in which two or more occupants, including the driver, share the use or cost, in traveling between fixed points on a regular basis (also referred to as ride sharing).

Census Block - A unit of spatial aggregation used by the U. S Bureau of the Census in reporting decennial census data, corresponding roughly to its colloquial meaning.

Census Block Groups - Block Groups are combinations of census blocks within census tracts and block numbered areas.

Census Tracts - Small areas with generally stable boundaries, defined within counties and statistically equivalent entities, usually in metropolitan areas and other highly populated counties. They are designed to be relatively homogeneous with respect to population characteristics, economic status, and living conditions.

Census Transportation Planning Package (CTPP) - A special tabulation of transportation related data for transportation analysis zones and larger areas. It includes data by place of residence, by place of work, and from a cross tabulation of place of residence by place of work for use in studying commuting patterns.

Central Business District (CBD) - An area of intense commercial development in the center of the City.

Centroid - An assumed point in a zone that represents the origin or destination of all trips to and from the zone.

Centroid Connector - Attached the centroid to the highway network: as such, it is a representation of all local streets in that zone.

Code of Federal Regulations - The Code of Federal Regulations is a set of the general and permanent rules published in the Federal Register by the Executive departments and agencies of the Federal Government. The Code is divided into 50 titles that represent broad areas subject to Federal regulation.

Collector - A street or highway that provides for traffic movement between major streets and local street. It is a road intended to collect traffic from local streets and land-access roads.

Community - A physical or cultural grouping of stakeholders with common interests created by shared proximity or use. Community can be defined at various levels within a larger context (e.g., neighborhood, city, or region).

Commute Alternatives - Carpooling, van pooling, transit, bicycling, walking, and telecommuting. Also includes any alternative work-hours program.

Commute - A repetitive home-to-work or work-to-home trip.

Commuter - Person who travels regularly between home and work or school.

Commuter Rail - The portion of main-line railroad transportation operations which encompass passenger train service for local short-distance travel between a central city and adjacent suburbs.

Comprehensive Planning - A planning process that requires inclusion of land use, transportation, water and sewer, education, health and other elements.

Conformity - Process to assess the compliance of any transportation plan, program or project with air quality implementation plans. The conformity process is defined by the Clean Air Act.

Congestion - "Recurrent" congestion is defined as a condition lasting for 15 minutes or longer where travel demand exceeds design capacity. That typically means freeway speeds were 50 km/h or less during peak commute periods on a typical incident-free weekday. "Non-recurrent" congestion is defined as backups caused by special circumstances, such as accidents, stalled vehicles, sporting events, etc. The consequences of congestion are longer and less predictable travel times.

Congestion Management System (CMS) - A systematic process that provides information on transportation system performance to decision makers for selecting and implementing cost-effective strategies to manage new and existing facilities so that traffic congestion is alleviated and the mobility of persons and goods is enhanced.

Congestion Mitigation and Air Quality (CMAQ) - The Congestion Mitigation and Air Quality Improvement Program directs funds toward transportation projects in Clean Air non-attainment areas for ozone and carbon monoxide. These projects will contribute to meeting the attainment of the NAAQS.

Cordon Line - An imaginary line enclosing a study area, along with external interviews are conducted, or along which travel counts are made.

Corridor - A geographic area that is defined by major roads and rail facilities, and major flows of travel. Transportation corridors are identified for the purpose of analyzing the patterns and flows of traffic between origins and destinations.

Cross Classification - Procedure used for determining trip productions by relating trip making to various household characteristics such as income, auto availability, or household size.

Daily Vehicle Miles Traveled (DVMT) - The total number of miles driven per day in a specified area by all vehicle types.
Deadhead Miles: Miles a transit vehicle travels without passengers or cargo on board.

Demand Management - A set of strategies that promote increased efficiency of the transportation system by influencing individual travel behavior.

Demand Response System (DMS) - Passenger trips are generated by calls from passenger to the transit dispatcher who on demand responds by dispatching a vehicle to provide a trip. Not a fixed route system.

Design Hourly Volume (DHV) - Total traffic in both directions generally representing the highest hour of volume of the future year chosen for design purposes.

Destinations - The zone in which a trip terminates.

Disadvantaged Business Enterprises (DBE) - Disabled Business Enterprise, Women’s Business Enterprise, and Minority Business Enterprise - all known as DBE’s and is a consideration for Federal funds guidelines of implementation.

Discrimination - Refers to any intentional or unintentional act, or any failure to act, which has the effect of excluding or denying a person from participation in benefits, or has otherwise subjected a person to unequal treatment under any program or activity because of race, color or national origin.

Divided Highway - A multi-lane facility with a positive barrier median, or a median that is 4 feet or wider.

Donor State Bonus - States that contribute more to the Highway Trust Fund than any receive back in Federal-aid highway programs. These states receive a predetermined amount based on a comparison of a projection of all payments into the Highway Trust Fund.