Federal Highway Administration (FHWA)

An agency of the United States Department of Transportation. FHWA administers the Federal-aid Highway Program, which provides financial assistance to States to construct and improve highways, urban and rural roads, and bridges. FHWA also administers the Federal Lands Highway Program, which provides access to and within national forests, national parks, Indian Tribal lands, and other public lands. FHWA is headquartered in Washington, DC, with field offices across the country, including one in or near each State capital.

Federal Transit Administration (FTA)

An agency of the United States Department of Transportation. FTA is the principal source of Federal financial assistance to America's communities for the planning, development, and improvement of public or mass transportation systems. FTA provides leadership, technical assistance, and financial resources for safe, technologically advanced public transportation that enhances mobility and accessibility, improves the nation's communities and natural environment, and strengthens the national economy. FTA is headquartered in Washington, DC, with regional offices in Atlanta, Boston, Chicago, Dallas, Denver, Kansas City, New York, Philadelphia, San Francisco, and Seattle.

Federal-Aid Highway(s)

Those highways eligible for assistance under Title 23 of the United States Code, which does not include those functionally classified as local or rural minor collectors.


A group of domains that coordinate to share resources while each domain retains its authority over its own resources. Federations are governed by negotiated agreements.

Field - Vehicle Communications

A wireless communications channel used for close-proximity communications between vehicles and the immediate infrastructure. It supports location-specific communications for ITS capabilities such as toll collection, transit vehicle management, intersection safety, driver information, and automated commercial vehicle operations. One of the types of architecture interconnects defined in ARC-IT.

Field Physical Objects

Infrastructure distributed near or along the transportation network, including 'intelligent' or 'smart' infrastructure which performs surveillance (e.g. traffic detectors, cameras), traffic control (e.g. signal controllers), information provision (e.g. Dynamic Message Signs (DMS)) and local transaction (e.g., tolling, parking) functions. Typically, their operation is governed by transportation management functions running in back offices. Field systems/devices also directly interface to vehicle or mobile Physical Objects. The Field class is one of the six general classes of Physical Objects defined in the Architecture, typically shown in orange on service package drawings.

First- and Last-Mile Problem

The extra time and hassle commuters face when they're going from home to a transit station and then from the station at the other end of the trip to a final destination.

Fixed Point - Fixed Point Communications

A communication link serving stationary entities. 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 Fixed Point - Fixed Point (FP2FP) communication the important issue is that it serves stationary entities. Both dedicated and shared communication resources may be used. One of the types of architecture interconnects defined in ARC-IT.

Fixing America's Surface Transportation Act (FAST Act)

Authorization of the federal surface transportation programs for highways, highway safety and transit for the five-year period 2016-2020.


The ability to adjust or adapt to external changes with little or no design changes.

Flexible route service

A transit service that follows a direction of travel but allows for deviation or rerouting along the way to accommodate specific trip requests. Examples of flexible route systems are route deviation and point deviation. The schedule may be fixed or flexible.

Flow Characteristics

Characteristics that govern the transmission and receipt of information flows within ARC-IT. Coordination relationships from the Enterprise View may imply Flow Characteristics:
a) An expectation of guaranteed delivery drives no-repudiation of receipt.
b) An expectation of information provision may drive regularity and periodicity.
c) An expectation of personal information exchange drives a high confidentiality requirement.

The context of Physical Objects may also imply certain Flow Characteristics:
a) Information flows between two mobile objects (vehicle or personal) are always restricted to wireless media.
b) Communications involving one mobile object and one fixed object involve wireless media, but may also include fixed media backhaul.
c) Communications between two vehicles use a short range (direct) low latency wireless technology.

Flow Hierarchy

The relative level of an information flow. Hierarchical relationships between flows are inclusive. If flow-B is a sub-flow of flow-A, that means that flow-A includes all of flow-B. Flow hierarchy is not illustrated in service packages and generally not seen on the ARC-IT website, but is used in some ITS standards and the SET-IT tool in limited fashion.


The process of forward sending data onto another entity (system user) without modifying or storing the data for any substantial length of time.

Free Flow Speed (for auto/truck modes)

The average speed of vehicles on a given segment, measured under low volume conditions, when drivers are free to drive at their desired speed and are not constrained by the presence of other vehicles or downstream traffic control devices; typically 5 mph over the posted speed limit.

Free Flow Time (for auto/truck modes)

The average time spent by vehicles traveling at the free flow speed over a facility length.


A multilane, divided highway with at least two lanes for exclusive use of traffic in each direction and full control of ingress and egress.

Functional Object

The building blocks of the Physical Objects of the physical view. Functional Objects group similar processes of a particular Physical Object together into an "implementable" package. The grouping also takes into account the need to accommodate various levels of functionality. Since Functional Objects are both the most detailed components of the physical view and tied to specific service packages, they provide the common link between the interface-oriented architecture definition and the deployment-oriented service packages.

Functional Requirement

A statement that specifies WHAT a system must do. The statement should use formal "shall" language and specify a function in terms that the stakeholders, particularly the system implementers, will understand. In ARC-IT, functional requirements have been defined for each Functional Object that focus on the high-level requirements that support regional integration.

Functional View

The part of ARC-IT that defines what has to be done to support the ITS services. It defines the processes that perform transportation functions and the data flows that are shared between these processes. The functional view was developed using Structured Analysis techniques to support and provide the detail for the physical view's Physical Objects and information flows.


The capabilities of the various computational, user interfaces, input, output, data management, and other features provided by a product.