Application Programming Interface (API) Standard for the Advanced Transportation Controller (ATC)

The Advanced Transportation Controller (ATC) Standards are intended to provide an open architecture hardware and software platform that can support a wide variety of Intelligent Transportation Systems (ITS) applications including traffic management, safety, security and other applications. The ATC Standards are being developed and maintained under the direction of the ATC Joint Committee (JC) which is made up of representatives from the American Association of State Highway and Transportation Officials (AASHTO), the Institute of Transportation Engineers (ITE), and the National Electrical Manufacturers Association (NEMA).

The ATC 5401 Application Programming Interface (API) for the Advanced Transportation Controller (ATC) Standard is one of three ATC standards efforts. It defines a software platform that operates on an ATC controller unit (as defined by the ATC 5201 Advanced Transportation Controller Standard. The API Software that is developed according to the standard provides management capabilities and functional interfaces for the ATC unit's Front Panel, Field Input/Output Devices, and Real-time Clock. When combined with the ATC units's Linux operating system, the API Software provides a universal interface for application programs to operate on any ATC unit regardless of the manufacturer. In addition, it allows multiple application programs to operate concurrently on a single ATC unit by sharing the controller's computational resources, its Front Panel, its Real-time Clock, and access to the Field I/O devices of the cabinet system.

The ATC 5401 has been prepared by the ATC API Working Group (WG), a technical subcommittee of the ATC JC. It establishes a common understanding of the user needs, requirements, and specification of the interface for:

  1. The local, state, and federal transportation agencies who specify ATC equipment;
  2. The software developers, consultants, and manufacturers who develop application programs for ATC equipment; and
  3. The public who benefits in the application programs that run on ATC equipment and directly or indirectly pays for these products.

Other standards within the ATC program include the ATC 5201 Advanced Transporation Controller Standard,  and the ATC 5301 ATC Cabinet Standard


ATC 5401 v02A

The Application Programming Interface (API) Standard for the Advanced Transportation Controller (ATC) Version 2 (v02.17) was published as a Joint Standard of AASHTO, ITE and NEMA on September 1, 2011. On September 12, 2013, it was republished with the “ATC 5401” identifier in the name for administrative purposes and without modification to the technical content of the standard. Following this, the ATC JC requested funding to build a software reference implementation of the ATC 5401 Standard that could discover and correct any deficiencies in the standard and provide API software that manufacturers could use freely in their controller units. This approach would provide the best opportunity for portability, compatibility, and interchangeability of ATC application software. This decision was supported by all controller manufacturers involved in the ATC program. Funding from the USDOT was received and resulted in the API Reference Implementation (APIRI) project (see

ATC 5401 v02A.35 represents a significantly improved version of the standard and rectifies the deficiencies in the previous version. This version of the standard correlates to the current status of the APIRI project. Improvements included:

  1. Editorial changes
  2. Changes to three of the existing Configuration Utilities
  3. Addition of three new Configuration Utilities
  4. Improved descriptions to seven API functions
  5. Corrections to eight API functions
  6. Addition of three new API functions
  7. Removed one function

The API WG submitted ATC 5401 Standard v02A.35 to the ATC JC for review as a Proposed Recommend Standard (pRS). The ATC JC accepted the document as a Recommended Standard during their teleconference on June 20, 2019 with a vote of 8 yeas, 0 nays, and 0 abstentions.

Notice of Intent to Adopt ATC 5401 Standard v02A

  • Notice of Intent to Adopt  Word | PDF
  • Standard Development Report for ATC 5401 v02A  Word | PDF
  • Recommended Standard ATC 5401 v02A  Word | PDF


ATC 5401 v02B.42 Application Programming Interface (API) for the Advanced Transportation Controller (ATC)

As part of the ATC standards maintenance efforts, User Comment Draft (UCD) ATC 5401 v02B.42 Application Programming Interface (API) for the Advanced Transportation Controller (ATC) is being distributed to the members of ITE and other standard development organizations (SDOs) for formal review. The standard contains the detailed design and requirements for software that runs on ATC transportation controller devices. Following this comment period, the comments received will be adjudicated by the ATC API Working Group (WG), UCD ATC 5401 v02B.42 will be updated accordingly, and the standard will be moved through the Recommended and Approved stages of the standards development process to publication

Comments from potential users of the standard are solicited and request comments be submitted by October 30, 2022 at

Effective Date of the Comment Period

The effective date of this action is October 3 - October 30, 2022

User Comment Draft ATC 5401 v02B.42 Application Programming Interface (API) for the Advanced Transportation Controller (ATC). The package is as follows:

  1. Standard Development Report (SDR) as PDF
  2. UCD ATC 5401 v02B.42 standard as: a) PDF and b) Word File with tracked changes.
  3. Comment Submittal Form as an XLSX file.

 How to Submit Comments

Inquiries, comments or proposed changes to this standard should written in the Comment Submittal Form and Emailed to: by October 30, 2022.



Version History Table

Version No.

Standard Name

Overall Status Under Development / Published / Superseded Version

Date Completed

    Project Schedule 10/11/2022

Standards Development Process Chart




ITE's Antitrust and Conflict of Interest Meeting Guidelines


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