NEMA - NTCIP 1202
National Transportation Communications for ITS Protocol Object Definitions for Actuated Signal Controllers (ASC) Interface - Version 03
|Publication Date:||1 February 2019|
Prior to the development of NTCIP 1202, there were no standards defining how ASCs communicate with host systems. As a result, each manufacturer has developed its own protocol to meet its own particular needs. This approach has resulted in systems that are not interchangeable or interoperable. If an agency wishes to use either a central management system or additional ASC from a different vendor, the agency encounters significant systems integration challenges, requiring additional resources to address. These additional resource requirements inhibit information sharing within and between various potential users of the data and prevent vendor independence. Without manufacturer independence, resource requirements further increase because of a lack of a competitive market.
These problems have not been limited to traffic signal controllers. Many other devices also need to exchange information. In surface transportation, examples include dynamic message signs, bus priority sensors, weather, and environmental monitoring, etc.
To address these problems, NTCIP is developing a family of open standards for communications between field devices and central management systems. NTCIP 1202 v03 is part of that larger family and is designed to define an interoperable and interchangeable interface between a transportation management system and an ASC, while still allowing for extensions beyond NTCIP 1202 v03 to allow for new functions as needed. This approach is expected to support the deployment of ASC from one or more vendors in a consistent and resource-efficient way.
NTCIP 1202 v03 standardizes the communications interface by identifying the various operational needs of the users (Section 2) and subsequently identifying the necessary requirements (Section 3) that support each need. NTCIP 1202 v03 then defines the NTCIP standardized communications interface used to fulfill these requirements by identifying the dialogs (Section 4) and related data concepts (Section 5) that support each requirement. Traceability among the various sections is defined by the Protocol Requirements List (Section 3.3) and the Requirements Traceability Matrix (Annex A). Conformance requirements for NTCIP 1202 v03 are provided in Section 3.3. NTCIP 1202 v03 only addresses a subset of the requirements needed for procurement. It does not address requirements related to the performance of the traffic detectors (e.g., accuracy, the supported detection range, the time it takes to detect conditions, etc.), hardware components, mounting details, etc.
Previous versions of NTCIP 1202 addressed only Actuated Traffic Signal Controllers (ASC) that employ vehicle or pedestrian detectors to activate a particular phase - the scope did not include pre-timed, or fixed-time signal controllers that cycle through phases regardless of the number of vehicles or pedestrians present. ASCs included both fully actuated traffic signals, where all phases are actuated, and phases are skipped if no vehicles or pedestrians are detected, as well as semi-actuated traffic signals, where at least one phase is guaranteed to be served regardless of whether pedestrians or vehicles are detected. For the NTCIP 1202 v03 purposes, controllers that allow different phases to be active (or skipped) at any point in time phase are known as phase-based controllers.
Beginning with NTCIP 1202 v03, the scope was expanded to standardize the communications interface between an ASC and a RoadSide Unit (RSU). An RSU is any connected vehicle field device that is used to broadcast messages to, and receive messages from, nearby vehicles using Dedicated Short Range Communications (DSRC).
An implementation of NTCIP 1202 v03 requires lower-level services to structure, encode, and exchange the data concepts defined by NTCIP 1202 v03. NTCIP 1202 v03 assumes that the data concepts are exchanged by one of the protocols defined in NTCIP 2301 v02.