Operational Technology Specifications Library (OTSL)

The OTSL gives requirements for Operational Technology products and services on motorways and all-purpose trunks roads, and related services.

Operational Technology Specifications Library (OTSL)

The OTSL replaces the historic Traffic Systems and Signing (TSS) Plans Registry and was launched in 2022.

It has inherited many of the TSS Plans Registry documents including specifications for equipment, and testing, as well as technical drawings and diagrams covering the following topic areas:

Prefix Description
MCE Specifications for equipment. Also see 'TRs'
MCG Specifications for testing. Also see 'TRGs'
MCH Instructions. A general sequence for: handbooks, guides, instructions, request forms, procedures, reports, and records. Also see 'TRHs'
MCL Drawings, specifications, records, and maintenance manuals for lines and transmission systems.
MCS Indices and lists
MCX Standard installation drawings, cabinets, circuit diagrams, and printed circuit boards.
TR Specifications for equipment. These specifications have been notified to Europe. Also see 'MCEs'.
TRG Specifications for testing. These specifications have been notified to Europe. Also see 'MCGs'.
TRH Instructions. These instructions have been notified to Europe. Also see 'MCHs'.

The OTSL forms part of a larger suite of documents specifying design, construction and operational requirements for motorways and all-purpose trunk roads, namely the Design Manual for Roads and Bridges (DMRB) standards and Manual of Contract Documents for Highway Works (MCHW) specifications.

Operational Technology comprises central systems, roadside technology and infrastructure used to monitor conditions on the road network, inform and instruct users of the road network, and manage the technology lifecycle.

  • A central system is something that is located at a real or virtual central location, remote from the roadside, for example a traffic management system or systems used by regional operation centre colleagues.
  • Roadside technology is any technology installed at the side, above, or under the carriageway of a motorway or all-purpose trunk road, for example a message sign or an emergency roadside telephone.

How to access the OTSL

If you work for us or our supply chain partners, you can request access to OTSL by emailing OTSL@nationalhighways.co.uk. Access is granted at our discretion.

The documents contained within the OTSL include current versions of Operational Technology specifications as procured by National Highways, related forms, and supporting information documents which can all be download from the library.

Legacy (products that remain in use but are no longer procured) and archived (products that are no longer in use or procured) versions of specification documents are available upon request by emailing OTSL@nationalhighways.co.uk

The OTSL does not contain the published documents in the DMRB or MCHW. Please see the Standards for Highways website to download copies of these documents.

Our plans for the OTSL

The structure and style of documents within the OTSL has started to be amended as of March 2024 to bring them in line with their companion documents in the DMRB and MCHW.

There will be a period of transition while the OTSL is being reviewed and updated and the document codes will comprise two different types of document prefix e.g. the old TSS Plans Registry style codes and the new codes that are being introduced. We expect this process to happen in a slow controlled manner over the next few years.

If you're interested in learning more about the new document codes, please sign up for access to the OTSL and download a copy of OG 1108 Overview of the Operational Technology Specifications Library.

Further information will be released to support the release of the updated documents and the main intention is to:

  1. draft documents using recognised National Highways drafting conventions for requirements documents e.g. ‘must’ for legislative requirements and ‘shall’ for requirements of the Overseeing Organisation.
  2. revise any references to Highways Agency Traffic Management System (HATMS) and its subsystems to reflect the introduction of the DYNAC traffic management system and Enterprise Service Bus (ESB) in England.
  3. revise any references to services, organisations and processes used to support the technology lifecycle (such as product acceptance, asset management etc) that may have changed or been renamed since the existing document was last updated.
  4. revise any references to other specifications (both OTSL and national/international standards) that may have been updated or retired since the existing document was last updated.

Contact details: For any queries, please email: OTSL@nationalhighways.co.uk