The practice of driving in such a way as to minimize fuel consumption and emissions.


A dedicated lane(s) optimized for the environment similar to high-occupancy vehicle lanes; however, these lanes are optimized for the environment using connected vehicle data. These lanes would be targeted toward low-emission, high-occupancy freight, transit, and alternative-fuel vehicles (AFV). Drivers would be able to opt in to these dedicated eco-lanes to take advantage of eco-friendly applications such as eco-speed limits, eco-cooperative adaptive cruise control and connected eco-driving applications.

Electronic On-Board Recorder

A device on-board a commercial vehicle used to record driver information such as hours of service.


An ITS system or piece of a system named as the name used by stakeholders. Elements are the basic building blocks of regional ITS architectures and project ITS architectures.

Elliptic Curve Cryptography

A form of public-key cryptography based on the problem of finding discrete logarithms in a group defined over elliptic curves.

Emergency Management and Response

Actions taken to prepare for, respond to, and recover from an incident threatening life, property, operations, or the environment (natural and manmade hazards).


Enhanced Metafile. A graphics file format, originated by Microsoft Corporation, that has many advantages over the older Windows metafiles (WMF). Images in EMF format can be resized without distortion and loss of detail.


To convert readable data to unreadable, encrypted data using an encryption algorithm and a key. See Decrypt.

Encryption Algorithm

An algorithm that takes as input plaintext and a key and produces ciphertext.

End-Entity Certificate

A certificate used to validate application PDUs or certificate requests.


The ultimate user of a product or service, especially of a computer system, application, or network.

Engineering Object

An implementation or realization of some abstract function. It may be implemented as hardware or as software.

Enrollment Certificate

A certificate used to validate a certificate request.

Enterprise Object

An organization or individual that interacts with other Enterprise Objects and/or Physical Objects. An Enterprise Object may be a component of another larger Enterprise Object, which may in turn be a component of a third, even larger, Enterprise Object (e.g., a Traffic Management Center Manager is a component of State DOT is a component of State Government). Enterprise Objects may participate wholly or in part in other Enterprise Objects (e.g., a Device Developer is a component of Auto Manufacturer but also participates in Standards Body).

Enterprise View

Describes the relationships between organizations and the roles those organizations play within the intelligent transportation system environment. This enterprise view provides the basis for understanding who the stakeholders will be and the roles these implementers could take in system conceptualization, development and operations.


Any physical or abstract thing of interest. For example, an entity may be a computer, an organization, a piece of software or a set of functions performed by a system.


The circumstances, objects, and conditions that surround a system to be built; includes technical, political, commercial, cultural, organizational, and physical influences as well as standards and policies that govern what a system must do or how it will do it.

Environmental Assessment (EA)

A document that must be submitted for approval by the U.S. Environmental Protection Agency and the U.S. Department of Transportation for transportation projects in which the significance of the environmental impact is not clearly established. An EA is required for all projects for which a Categorical Exclusion or Environmental Impact Statement is not applicable.

Environmental Impact Statement (EIS)

A document that must be submitted for approval by the U.S. Environmental Protection Agency and the U.S. Department of Transportation for transportation projects that significantly affect the human environment as defined by CEQ (Council on Environmental Quality) regulations. The type of actions which would normally require an EIS are: a new controlled access freeway; a highway project of four or more lanes on new location; new construction or extension or fixed rail transit facilities; and new construction or extension of a separate roadway for buses or high-occupancy vehicles not located within an existing highway facility.

Equipment Package

Legacy term from the National ITS Architecture v7.1. See Functional Object

Evaluation Results

A legacy document of the National Architecture that contains a concise summary of the various evaluations that were performed in five other National ITS Architecture documents: Evaluatory Design, Communications Document, Cost Analysis, Performance and Benefits Study, and Risk Analysis.

Evaluation Stage

The second of three stages in the Corridor Planning and Screening Process, during which multiple corridor options are evaluated against meeting the preliminary mobility and connectivity needs identified during the concept stage. The range of corridor options considered includes operational strategies to optimize efficiency for all modes, capacity improvements within existing facility rights of way, or new facilities or alignments. High level costs and potential financing or partnership opportunities are also considered during this stage.

Evaluatory Design

A legacy document of the National ITS Architecture that supports evaluation of the National ITS Architecture's performance, benefits, and costs for three conceptual scenarios at various points in time. The scenarios consist of "typical" deployment environments: urban, inter-urban, and rural. The entire document will assist you in developing an evaluation methodology for the architecture that you have developed for your particular region or project.

Event Snapshot

A snapshot generated when a connected vehicle or other type of probe has a sensor value that exceeds a specific threshold.


The ability to add or modify functionality or features with little or no design changes.