National ITS Architecture Glossary

Legislation passed in 2005 that authorized the federal surface transportation programs for highways, highway safety, and transit.

Scalable Vector Graphics (SVG) is a language for describing two-dimensional graphics and graphical applications that is backed by the World Wide Web Consortium. Graphics described in SVG file format can be scaled without losing graphic quality. SVG files can be compressed to accommodate faster downloads of the graphic. The National ITS Architecture uses compressed SVG format to view the data flow diagrams (DFDs) from the logical architecture. The first time you open one of these diagrams you may be prompted to download an SVG Viewer as an add-on to your existing Web Browser.

The protection of ITS itself is comprised of security services that protect ITS systems and the communications between them. See the Security Document for more information.

A document of the National Architecture that presents an overview of the topic of security in the National ITS Architecture. It provides the context and considerations for using the security-related parts of the National ITS Architecture. This document also provides high-level guidance to agencies that desire to include security considerations in their regional ITS architectures and project ITS architectures. In addition to defining eight functional security areas as part of the National ITS Architecture, this document also discusses securing ITS itself.

Providing security for the surface transportation system has a set of desired outcomes (or objectives). How well a security system performs can be measured by the extent to which it meets the desired objectives.

Security services are typical security mechanisms or countermeasures that provide for different aspects of security.

Security threats are events or circumstances that adversely impact a surface transportation system or communication between systems.

The service packages, formerly known as market packages, provide an accessible, service-oriented perspective to the National ITS Architecture. They are tailored to fit, separately or in combination, real world transportation problems and needs. Service packages collect together one or more equipment packages that must work together to deliver a given ITS service and the architecture flows that connect them and other important external systems. In other words, they identify the pieces of the physical architecture that are required to implement a particular ITS service. Service packages are implemented through projects (or groups of projects, aka programs) and in transportation planning, are directly related to ITS strategies used to meet regional goals and objectives.

A document of the National Architecture that expands upon the service package discussion in the Implementation Strategy document by providing a comprehensive review of each of the service packages describing how service packages can be used to plan and implement integrated transportation systems customized to local needs. This document includes a number of examples that illustrate ways service packages can be applied in regional ITS architecture and project ITS architecture development activities. Through these definitions, analyses, and examples, the Service Packages document provides a comprehensive review of the service packages and how they can be used to plan and implement integrated transportation systems customized to local needs.

A widely used term that notates a public agency, private organization or the traveling public with a vested interest, or a "stake" in one or more transportation elements within a regional ITS architecture or project ITS architecture.

Documented technical specifications sponsored by a Standards Development Organization (SDO) to be used consistently as rules, guidelines, or definitions of characteristics for the interchange of data. A broad array of ITS standards is currently under development that will specifically define the interfaces identified in the National ITS Architecture.

A document of the National Architecture that discusses the issues that are involved in the development of system interface standards. It was primarily intended as a planning document for US DOT and the Standards Development Organizations.

A statewide prioritized listing/program of transportation projects covering a period of at least four years that is consistent with the long-range statewide transportation plan (LRSTP), metropolitan transportation plans (MTPs), and transportation improvement plans (TIPs), and is required for projects to be eligible for funding under title 23 U.S.C. and title 49 U.S.C. Chapter 53.

The official statewide multimodal, long-range transportation plan addressing no less than a 20-year planning horizon that is developed, adopted and updated by the state DOT through the statewide transportation planning process.

The principle structural element of the physical architecture of the National ITS Architecture. Subsystems are individual pieces of the Intelligent Transportation System defined by the National ITS Architecture. Subsystems are grouped into four classes: Centers, Field, Vehicles, and Travelers. Example subsystems are the Traffic Management Subsystem, the Vehicle Subsystem, and the Roadway Subsystem. These correspond to the physical world: respectively traffic operations centers, automobiles, and roadside signal controllers. Due to this close correspondence between the physical world and the subsystems, the subsystem interfaces are prime candidates for standardization.

A diagram which depicts all subsystems in the National ITS Architecture and the basic communication channels between these subsystems. The subsystem diagram is a top-level architecture interconnect diagram. Variations of the subsystem diagram are sometimes used to depict regional ITS architectures or project ITS architectures at a high level.

A collection of hardware, software, data, processes, and people that work together to achieve a common goal. Note the scope of a "system" depends on one's viewpoint. To a sign manufacturer, a dynamic message sign is a "system". To a state DOT, the same sign is only a component of a larger Freeway Management "System". In a regional ITS architecture or project ITS architecture, a Freeway Management System is a part of the overall surface transportation "system" for the region.

The list of all ITS-related elements in a regional ITS architecture or project ITS architecture.

Defined by International Council on Systems Engineering (INCOSE) as an interdisciplinary approach and means to enable the realization of successful systems. It focuses on defining customer needs and required functionality early in the development cycle, documenting requirements, and then proceeding with design synthesis and system validation while considering the complete problem. Systems engineering integrates all the disciplines and specialty groups into a team effort forming a structured development process that proceeds from concept to production to operation. Systems engineering considers both the business and the technical needs of all customers with the goal of providing a quality product that meets the user needs.