Proposal to clarify that the parking brake may be actuated while the vehicle is in motion via actuation of the vehicle’s service braking system by means of an auxiliary control which could be an Electronic Parking Brake (EPB) and to promote consistent interpretation of the activation conditions for an Emergency Stop Signal (ESS), including by application of the service braking system via the EPB control.

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 amend para. 2.8 of Annex 8 to add subparagraph (c). The amendment addresses trailers utilizing service braking system energy reserves for automatic brake requirements. Current para. 2.8 includes options (a) and (b) requiring spring brake pressure reduction or corresponding pressure reduction in spring compression chamber. New subparagraph (c) permits alternative designs where combined service braking and parking braking system activation holds a laden trailer on 18 percent gradients at any service brake energy reservoir pressure from 850 kPa to 0 kPa, providing greater realization flexibility while maintaining required holding performance.

Proposal to amend para. 2.8 of Annex 8 to UN R13 to require trailers utilizing service braking system energy reserves to fulfil one of three requirements when uncoupled and park brake control released: pressure in spring brake compression chamber shall reduce to 0 kPa when energy reserves reduce to 280 kPa, pressure reduction in service braking system energy reserve results in corresponding reduction in spring compression chamber pressure, or combined service and parking braking forces shall hold laden trailer as required when service brake energy reservoir reduces from 850 kPa to 0 kPa.

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.

Proposal to amend para. 2.8 of Annex 8 to add a new requirement that braking forces from combined service and parking braking systems shall hold a laden trailer as required in Annex 4 para. 3.2.1 at any time when service brake energy reservoir pressure reduces from 850 kPa to 0 kPa, ensuring continuous trailer immobilisation during service brake pressure depletion while establishing a performance-based requirement rather than prescribing specific technical solutions.