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NTCIP 1211 - Object Definitions for Signal Control and Prioritization (SCP)

This fact sheet was updated 9/18/2009. The current standard was 1211 0138, which was balloted in 2005 and published in 2008. A draft of Version 02 is being prepared.

This Fact Sheet was written on September 18, 2009. The status of the standard at the time was: Published in May 2008.

This Fact Sheet was last verified on September 18, 2009


The National Transportation Communications for Intelligent Transportation System (ITS) Protocol (NTCIP) is a family of standards that provides both the rules for communicating (called protocols) and the vocabulary (called objects) necessary to allow electronic traffic control equipment from different manufacturers to operate with each other as a system. The NTCIP is the first set of standards for the transportation industry that allows transportation systems to be built using a "mix and match" approach with equipment from different manufacturers. Therefore, NTCIP standards reduce the need for reliance on specific equipment vendors and customized one-of-a-kind software. To assure both manufacturer and user community support, NTCIP is a joint product of the National Electronics Manufacturers Association (NEMA), the American Association of State Highway and Transportation Officials (AASHTO), and the Institute of Transportation Engineers (ITE). More information concerning the NTCIP family of standards and their related documents is available in the NTCIP 9001 - NTCIP Guide, available on-line at (www.ntcip.org).

Human communication relies on a vocabulary of words, each defined with a fixed meaning and spelling that are understood by the members of the conversation group. Computers have a similar vocabulary, called "objects" in the NTCIP standards. These objects define all possible commands, responses and information that may be exchanged among microprocessor-controlled electronic equipment, traffic management systems (which could include central computers housed in a center or portable computers, e.g. laptops), and by extension, their human operators. The NTCIP groups these objects by subject material (e.g., actuated signal controllers) and calls these groupings "object definitions." The objects defined in this standard allow for the interaction between vehicles, management centers and signal controllers to support signal prioritization for specifically-equipped vehicles.

What are these standards for?

This standard, NTCIP 1211 - Object Definitions for Signal Control and Prioritization (SCP), provides the vocabulary - commands, responses and information - necessary for traffic management centers, including traffic management, emergency management, transit management, and other fleet management centers and their respective vehicles to interact with, control, manage, and monitor transportation signal controllers implementing vehicle prioritization schemes. This standard includes a description of signal control and prioritization scenarios and possible configurations. This standard also contains object definitions to support the functionality of each scenario, conformance group requirements and conformance statements to support compliance with the standard.

Who uses them?

This standard, NTCIP 1211 - Object Definitions for Signal Control and Prioritization (SCP), should be used by transportation professionals including transit and traffic engineers involved with the design, specification, selection, procurement and installation, operation, and maintenance of signal control and prioritization systems. ITS product hardware and software designers and application (computer program) developers should find this standard especially relevant to their efforts.

How are they used?

This standard, NTCIP 1211 - Object Definitions for Signal Control and Prioritization (SCP), defines a vocabulary of "objects" used to assure that the transportation management center computer-based devices, signal controllers, fleet vehicles and fleet management centers "speak" a common language. A message must be understood by the device it was intended for, and equally important, it must not be misunderstood or misinterpreted by another device on the same network. Object definitions unambiguously define the content, terminology, units and format of commands, responses and information affecting communications between priority-capable actuated traffic signal controller units, vehicles and management systems. Further, this standard defines scenarios for implementation of signal prioritization schemes, including the sequence of events required for each scenario.

This standard must be used with one of the NTCIP communications profiles (see related NTCIP documents below) which provide the communications channel for information transfer between devices. It must be used with the NTCIP 1202, which provides the object definitions for actuated traffic signal controller units, and the NTCIP Global Object Definitions (NTCIP 1201), which provides the glossary of common object definitions used by multiple NTCIP devices.


Implementation of signal prioritization schemes are accomplished by using the objects and management structure defined in NTCIP 1211 - Object Definitions for Signal Control and Prioritization (SCP). Communications between a priority request-equipped fleet vehicle, transportation management center’s central computer, fleet management center’s central computer and prioritization-equipped signal controllers are accomplished by the objects defined in this standard. These objects define the information, commands and responses that must be understood by the devices at both ends of the communications channel.

Related documents

The following ITS standards and documents are related and should be considered when using this standard:

The following standards and documents, while not part of the ITS standards, should also be considered when using this standard:

How to obtain Standards
American Association of State Highway and Transportation Officials
Institute of Transportation Engineers
Association of Electrical and Medical Imaging Equipment Manufacturers (NEMA), formerly known as National Electrical Manufacturers Association