Report from the 5th session of the informal working group on Automated Connections between Vehicles working on language to integrate such systems within UN R13 (heavy-duty braking) and UN R55 (mechanical couplings).

Denmark submitted GRRF-71-19 (subsequently in GRRF/2012/12) proposing a new paragraph to require a test point between the coupling head and the trailer relay emergency valve. This document argues that the requirement is already implicit within UN R13 and therefore, that the change is unnecessary.

This document addresses the ramifications of introducing the proposals outlined in GRRF-72-07 (superceded by GRRF-72-07/Rev.1) specifically associated with semi-trailers.

Denmark submitted Document GRRF-71-18 (subsequently integrated into GRRF/2012/12) proposing to narrow the limits for coupling force control systems which are allowed to override the compatibility bands. This document argues against the proposed changes.

Denmark submitted document GRRF-71-19 (subsequently integrated into GRRF/2012/12) proposing to narrow the compatibility bands for control line pressure versus brake rate. This document challenges the proposed changes as effectively mandating electronic braking and imposing unwarranted costs.

Proposal to introduce provisions for electric regenerative braking systems.

Proposal to introduce provisions for electric regenerative braking systems.

Proposal for amendments to the draft provisions on e-trailers.

Proposal to introduce provisions for the approval braking systems for e-trailers and Electric Regenerative Braking (ERB) in towed vehicles of Category O.

Proposal to amend para. 2.2.2.4. to include electric regenerative braking system and electric propulsion system, amend para. 2.21. to define Electric Regenerative Braking (ERB), add para. 2.56. to define e-trailer, amend para. 5.2.2.7. regarding braking surface connection and electrical regenerative braking system disconnection, insert para. 5.2.2.26. establishing special requirements for e-trailers and trailers equipped with ERB of Category O₃ or O₄, insert Annex 4 paras. 1.7.1.3., 3.1.2.6., and 3.1.3.5. requiring ERB system deactivation during brake applications and tests, insert Annex 13 para. 4.7. requiring anti-lock braking system for vehicles with ERB, and amend Annex 16 tables to include trailer regenerative system parameters, based on GRVA/2025/15.

Proposal to establish definitions for “e-axle”, “e-axle trailer” and “dynamo function” and to establish provisions for the approval of e-axle trailers with regard to their “dynamo function”.

This document proposes amendments to UN Regulation 13 for trailers with dynamo function, superseding GRVA-22-26, GRVA-2025-15, and GRVA-21-12. The dynamo function converts vehicle kinetic energy into electrical energy without affecting braking system forces and is limited to trailers of category O₂, O₃, and O₄ pending further development. Maximum retardation power limits are 22 kW for O₃/O₄ trailers and 2 kW for O₂ trailers, measured using specified methods. Requirements include wheel locking prevention with braking rate not exceeding 0.04 per wheel, functional safety assessment per Annex 18, and demonstration that anti-lock and stability control systems comply when dynamo function is enabled. The dynamo function shall not be used during brake application testing. Administrative amendments update Annexes 2, 4, 5, 10, 19, 20, and 21 to reference e-axles and dynamo functions.

The e-Trailer Industry Group reports on discussions regarding electrically propelled and recuperating trailers. ISO 11992-2 Edition 4 is not safely implementable due to incompatibility with current UN regulations, missing PGNs, and risks of malfunction. ISO/TC 22/SC 31/WG 4 launched Edition 5, targeting publication in early 2027. Amendments to UN R13 and UN R100 are being developed in phases, with Phase 1 addressing trailer dynamo function and Phase 2 addressing e-axle trailers. Two workshops with Contracting Parties are planned to establish shared understanding and develop concrete parameter extensions for amending UN Regulations.

Proposal to delete paragraph 1.2.6. excluding e-axle trailers with e-axles providing electric propulsion and/or incorporating an electric regenerative braking system from the scope of UN R13, and add definitions of “e-axle,” “e-axle trailer,” “dynamo function,” and “e-trailer”; add special requirements for power-driven vehicles supporting e-trailer operation, e-axle trailers equipped with dynamo function, and e-trailers of category O; add requirements for electric control lines conforming to ISO 11992-2:²⁰²⁷; specify message support and functional compatibility; and add provisions for electric regenerative braking, dynamo function, and propulsion, including parameters such as retarder torque demand priority, propulsion force limits, overriding mode activation at speeds below 15km/h, and vehicle stability function interaction.