Capacity (for auto/truck mode)

The maximum number of vehicles that reasonably can be expected to traverse a point or a uniform section of roadway during a given time period under prevailing conditions.


Characterization of the relationship between the number of sender(s) and receiver(s) of a data exchange, e.g., broadcast (one-to-all) unicast (one-to-one) or multicast (one-to-multiple).

Categorical Exclusion

A formal ruling by the U.S. Environmental Protection Agency and the U.S. Department of Transportation that a transportation project or group of projects do(es) not individually or cumulatively have a significant environmental effect on the natural or human environment.

Census Transportation Planning Products Program (CTPP)

A unique partnership between state DOTs, metropolitan planning organizations (MPOs), the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA) and the U.S. Census Bureau (CB). State DOT and MPO funding, coordinated through AASHTO and FHWA, supports the development of special custom data tabulations from the CB, using data from the American Community Survey (ACS). These funds also support on-demand technical assistance, training, and research designed to support transportation planning, policy analysis, and travel demand modeling.


An entity that provides application, management, administrative, and support functions from a fixed location not in proximity to the road network. The terms "back office" and "center" are used interchangeably. Center is a traditionally a transportation-focused term, evoking management centers to support transportation needs, while back office generally refers to commercial applications. From the perspective of ARC-IT these are considered the same.

Center Physical Objects

Physical Objects that provide management, administrative, and support functions for the transportation system. The centers each communicate with other centers to enable coordination between modes and across jurisdictions. Some examples of center objects are Traffic Management, Transit Management, Commercial Vehicle Administration, Archived Data Management, Emissions Management, Payment Administration, Emergency Management, Transportation Information, and Fleet and Freight Management. The Center class is one of six general Physical Object classes defined in ARC-IT.

Center to Center Communications

A communication link serving stationary entities, including center Physical Objects. It may be implemented using a variety of public or private communication networks and technologies. It can include, but is not limited to, twisted pair, coaxial cable, fiber optic, microwave relay networks, spread spectrum, etc. In center to center communication the important issue is that it serves stationary objects. Both dedicated and shared communication resources may be used. One of the types of architecture interconnects defined in the Architecture Reference for Cooperative and Intelligent Transportation (ARC-IT).

Center to Field Communications

A communication link serving stationary entities, including center physical and field based objects. It may be implemented using a variety of public or private communication networks and technologies. It can include, but is not limited to, twisted pair, coaxial cable, fiber optic, microwave relay networks, cellular, spread spectrum, etc. In center to field communication the important issue is that it serves stationary objects. Both dedicated and shared communication resources may be used. One of the types of architecture interconnects defined in the Architecture Reference for Cooperative and Intelligent Transportation (ARC-IT).


See digital certificate

Certificate Authority

An entity that issues certificates to entities that are entitled to them.

Certificate Revocation List

A list identifying certificates that have been revoked. See: revocation.

Certificate Signing Request

A protocol data unit (PDU) sent from an entity to a certificate authority (CA), requesting that the CA issues a certificate on behalf of the entity

Clean Air Act (CAA)

The original Clean Air Act was passed in 1963, but the national air pollution control program is actually based on the 1970 revision of the law. The Clean Air Act as amended in 1990 made major changes and contains the most far-reaching revisions of the 1970 law.

Combination truck

A truck consisting of a tractor and trailer (FHWA Vehicle Category Classification Classes 8-13).

Commercial Motor Vehicle

Commercial motor vehicle means any self-propelled or towed motor vehicle used on a
highway in interstate commerce to transport passengers or property when the vehicle:
1) Has a gross vehicle weight rating or gross combination weight rating, or gross vehicle weight or gross combination weight, of 4,536 kg (10,001 pounds) or more, whichever is greater; or

2) Is designed or used to transport more than 8 passengers (including the driver) for compensation; or

3) Is designed or used to transport more than 15 passengers, including the driver, and is not used to transport passengers for compensation; or

4) Is used in transporting material found by the Secretary of Transportation to be hazardous under 49 U.S.C. 5103 and transported in a quantity requiring placarding under regulations prescribed by the Secretary under 49 CFR, subtitle B, chapter I, subchapter C.
(Source: 49 U.S.C. 31132)

Commercial Vehicle Operations

This area addresses the management of the efficiency, safety, and operation of commercial vehicle fleets and the movement of freight. It includes activities that expedite the authorization process for freight to move across national and other jurisdictional boundaries, activities that expedite inter-modal transfers of freight and the operation of freight vehicles that exchange information on the motor carrier, the vehicle, the driver, and, in some cases, the cargo to enhance freight operations and management.

Communications View

One of four views (along with the physical, functional, and enterprise views) defined by the Architecture Reference for Cooperative and Intelligent Transportation (ARC-IT). The communications view includes all of the communications equipment (e.g., wired and wireless transmitters and receivers) and the information management and transport capabilities necessary to transfer information among objects in the physical view in an interoperable manner.


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 or city or metropolitan area or region).

Community Impact Assessment (CIA)

A process to evaluate the effects of a transportation action on a community and its quality of life. The main areas of emphasis for a Community Impact Assessment are social, economic, land use, aesthetic, relocation and displacement, and civil rights.

Concept of Operations (ConOps)

For a specific project, the document in which the project stakeholders document their shared understanding of the system to be developed and how it will be operated and maintained. A user-oriented document that describes a system's operational characteristics from the end user's viewpoint.

Concept Strategy

The first of three stages in the Corridor Planning and Screening Process, during which the study area is identified, policy objectives are defined, preliminary mobility and connectivity needs are summarized, economic development opportunities are identified, a list of potential corridor options is compiled, high-level environmental and community issues and resources are identified, an initial list of FDOT and partner commitments is developed, and a corridor purpose and need is developed. The products of the Concept Stage include a Concept Report, summarizing all of the above, and a framework for further study, including potential corridor segments that may be advanced for further study and the types of study recommended.


An interest in the system relevant to one or more stakeholders. Concerns may apply to any phase of the system life cycle. However, some concerns may apply more during system design, implementation, operations, or maintenance and not during other phases of the system's life. A concern could be manifest in many forms, such as in relation to one or more stakeholder needs, goals, expectations, responsibilities, requirements, design constraints, assumptions, dependencies, quality attributes, architecture decisions, risks or other issues pertaining to the system.


As used in growth management, the requirement that public facilities and services needed to support development shall be available at the same time the impacts of such development will occur. For transportation facilities and services, there are specific legal criteria that address the time requirements for providing services and facilities, jurisdiction over level of service standards for specific portions of the highway and road system, and other issues.


Preserving authorized restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information. A loss of confidentiality is the unauthorized disclosure of information.

Confidentiality (communications)

A cryptographic service that provides assurance that only the intended recipients of a protocol data unit (PDU) can read it.

Configurable Parameter

Non-static data that can be adjustable and updated when needed.


Data that is used to customize the operational environment for a System Element or System User, or the System as a whole.


The process of selecting from a set of option(s) or alternative values in order to create a specific operational environment.


Under subsection 176(c) of the Clean Air Act Amendments of 1990, defined as agreement "... to an implementation plan's purpose of eliminating or reducing the severity and number of violations of the National Ambient Air Quality Standards (NAAQS) and achieving expeditious attainment of such standards..." ensuring that "...such activities will not cause or contribute to any new violation of any standard in any area; increase the frequency or severity of any existing violation of any standard in any area; or delay timely implementation of any standard or any required interim emission reductions or other milestone on any area."

Congestion (for the auto mode)

A condition in which traffic demand causes the level of services (LOS) to be at or below FDOT's LOS standard. Congestion is described as mild, heavy, or severe. Adjectives describing the types of congestion are nonrecurring and recurring.

Congestion Management Process (CMP)

A systematic approach required in transportation management areas (TMAs) that provides for effective management and operation, based on a cooperatively developed and implemented metropolitan-wide strategy of new and existing transportation facilities eligible for funding under title 23 U.S.C. and title 49 U.S.C. through the use of operational management strategies. Provides information on transportation system performance and finds alternative ways to alleviate congestion and enhance the mobility of people and goods, to levels that meet state and local needs.

Connected Automated Vehicle

A vehicle that is both a connected vehicle and an automated vehicle

Connected Device

A Physical Object that includes means to send and receive data to/from other Physical Objects.

Connected Vehicle

A vehicle connected device that is equipped with onboard equipment (OBE) that is active and operational and includes the means to send and receive data to and from other connected devices.


A mode of network communication where application information is exchanged between two computers through one or more data packets without previously establishing a session. UDP/IP is an example of a protocol implementing connectionless communications.


A mode of network communication where a session is established between two computers prior to sending any application information. TCP/IP is an example of a protocol implementing connection-oriented communications.


Highways, rail lines or waterways that connect hubs and corridors.

Constrained Connector

A connector that is not suitable for future expansion due to capacity/geometrics or facility plans. Constrained connectors have been identified in the workshop draft materials only when a connector or new alignment is funded in an adopted cost-feasible plan.


An externally imposed limitation on system requirements, design, or implementation or on the process used to develop or modify a system. A constraint is a factor that lies outside of -- but has a direct impact on -- a system design effort. Constraints may relate to laws and regulations or technological, socio-political, financial, or operational factors.

Container on Flatcar (COFC)

Containers resting directly on railway flatcars without a truck chassis underneath. (See also Trailer on flatcar.)


In project management, a legally binding document agreed upon by the customer and the hardware or software developer or supplier; includes the technical, organizational, cost, and/or scheduling requirements of a project.


To exercise influence over.

Control Channel

A single radio channel, not a service channel, intended for the exchange of management frames, including Wireless Access in Vehicular Environments (WAVE) Service Advertisements, and WAVE Short Messages.

Control Delay

For signalized intersections, the portion of the total delay attributed to traffic signal operation.

Controlled Access Facility

A roadway where the spacing and design of driveways, medians, median openings, traffic signals and intersections are strictly regulated by consideration of such factors as traffic volume, number of lanes and adjacent land use.

Controller Area Network

A Controller Area Network (CAN) bus is a message-based protocol, designed specifically for automotive applications. The CAN bus is one of five protocols used in the OBD-II vehicle diagnostics standard. The OBD-II standard has been mandatory
for all cars and light trucks sold in the United States since 1996.

Cooperative ITS

Subset of ITS where information is shared among physical objects based on mutual security agreements through a credentialing system

Coordinated Universal Time (UTC)

The primary time standard by which the world regulates clocks and time. UTC serves to accommodate the timekeeping differences that arise between atomic time (which is derived from atomic clocks) and solar time (which is derived from astronomical measurements of the Earth's rotation on its axis relative to the Sun). Since Jan. 1, 1972, UTC has been modified by adding "leap seconds" when necessary.


Rules that guide the relationships between viewpoints. Generally speaking, elements in one view may be referenced in some fashion in at least one other view.


Any land area designated by the state, a county, or a municipality which is between two geographic points and which is used or is suitable for the movement of people and goods by one or more modes of transportation (aviation, bicycle, highway, paratransit, pedestrian, pipeline, rail [commuter, intercity passenger, and freight], transit, space, and water), including areas necessary for management of access and securing applicable approvals and permits.

Corridor (for auto/truck modes)

1) A set of essentially interrelated, parallel transportation facilities for moving people and goods between two points;
2) A geographic area used for the movement of people and goods;
3) Highway, rail line, waterway, bikeway, and other exclusive-use facilities that connect major origin/destination markets.

Cost Analysis

A document of the National ITS Architecture that has two purposes. First, it develops a high level cost estimate of the expenditures that are associated with implementing ITS components. Second, it is a costing tool for implementers, by providing unit prices and systems costs of ITS subsystems. There is significant correlation between the Cost Analysis and the Evaluatory Design documents; the cost analysis is based largely on the assumptions made for the three deployment scenarios (urban, interurban, and rural).

Cost-Feasible Plan

A phased plan of transportation improvements that is based on (and constrained by) estimates of future revenues.

Coverage Area

A geographic jurisdiction within which a system provides services.

Cross Support

An agreement between two or more organizations to exploit the technical capability of interoperability for mutual advantage, such as one organization offering support services to another in order to enhance or enable some aspect of a mission.


A private key, public key or certificate