ITS Standards Program

ITS Standards Advisories provide the ITS transportation community with information and guidance on the consideration and use of ITS standards.

C2C Introduction

Relevance to U.S. DOT Research Initiatives and the National ITS Architecture

U.S. DOT Research Initiatives

C2C communications support the following US DOT Research Initiatives:

• Emergency Transportation Operations
• Integrated Corridor Management Systems
• Clarus
• Mobility Services for All Americans
• Vehicle Infrastructure Integration (VII)

More information on how the initiatives map
ITS Standards

Relevance to the National ITS Architecture

The NTCIP C2C communications standards are common across all Center-to-Center interfaces in the National ITS Architecture.

More information on the National ITS Architecture.

Center-to-Center (C2C) communications span the entire ITS domain, covering the exchange of data between computers physically located in different transportation management center facilities (e.g., traffic management centers, transit management centers, emergency management centers, and parking management centers). C2C standards enable this data exchange, specifying what information is exchanged, how and when it is exchanged, and the underlying transport mechanisms. C2C standards can be divided into two categories: (1) the message and data content and (2) the rules for exchanging the messages and data. The focus of this ITS standards advisory is the latter category, which we refer to in this advisory as C2C communications profile standards. Other ITS standards define the former category of specific message/data content, such as the Traffic Management Data Dictionary and Message Sets for External TMC Communication (TMDD and MS/ETMCC), Data Dictionary and Message Set for Advanced Traveler Information Systems (ATIS), Transit Communications Interface Profile (TCIP), and Family of Standards for Incident Management Message Sets. The two categories of standards work together to successfully exchange meaningful ITS-related information.

Consensus-based working groups from AASHTO, ITE, and NEMA are chartered with developing a set of underlying C2C communications standards for the transportation community, called the National Transportation Communications for ITS Protocol (NTCIP) standards. NTCIP organizes its standards using a layered approach as shown in Figure 1, similar to the ISO Open System Interconnection (OSI) framework model. While message/data standards address the Information Level, NTCIP C2C communications standards primarily address the Application, Transport, and Subnetwork Levels. At these levels, ITS and NTCIP leverage existing computer and telecommunications industry base standards, and specify what is mandatory and optional where alternatives are available for ITS applications. In some cases, the NTCIP standards have extended the industry base standard to meet the specific needs of the transportation community. In this manner, the NTCIP C2C communications standards are "profiles" of base standards and other standards.

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C2C Standards Framework