Proposal to establish a new supplement to UN Regulation No. 179, improving and correcting brake emissions measurement procedures for light-duty vehicles of categories M₁ and N₁. The regulation applies full-friction braking testing on brake dynamometers using the WLTP-Brake cycle comprising ten trips and 303 brake deceleration events. Testing includes three sections: cooling air adjustment, brake bedding with five cycle repetitions, and emissions measurement with three cycle repetitions. Compliance is demonstrated by measuring PM10 and SPN10 emissions from brake corner emission family parents, with whole-vehicle emissions calculated using friction braking share coefficients specific to vehicle electrification types. PM10 limits are 3 mg/km for M₁/N₁ vehicles and 5 mg/km for N₁ Class III/N₂ vehicles. Conformity of production requires annual testing of brake corner emission families with statistical evaluation per decision charts through 31 December 2029 (Phase I, PM10 only), with Phase II from 1 January 2030 evaluating both PM10 and SPN10. A version of this document with tracked changes is available.

Proposal to establish a new UN Regulation transposing UN GTR No. 24 into uniform provisions concerning approval of non-original and identical replacement brake parts (brake pads, drum brake linings, brake discs, and brake drums) with regards to particle emissions. The regulation applies to vehicles of category M₁, N₁, and N₂ between 3.5 and 5 tonnes maximum mass. Replacement brake parts must comply with particle emission limits, with emission factors calculated using test wheel load and friction braking share coefficient for the brake emissions family parent. Approval marks must be affixed to approved parts, and conformity of production shall be verified through sampling and testing procedures.

Proposal to establish a globally harmonised laboratory methodology for measuring brake particulate matter and particle number emissions from Heavy-Duty Vehicles. The UN GTR defines the test cycle (Worldwide Harmonized Heavy Duty Brake Cycle), minimum system requirements, test conditions, equipment preparation, brake dynamometer capabilities, brake enclosure design, sampling tunnel design, and sampling plane design. It applies to vehicles of categories M₂, M₃, N₂, N₃, and O₃, O₄ concerning braking, covering both friction braking systems (disc and drum brakes). The regulation includes requirements for brake bedding procedures, emissions measurements, calibration, and ongoing quality controls. A version with tracked changes is available.

Proposal to amend para. 6.1.10. to address division by zero cases when an OVC-HEV consumes zero fuel under charge-depleting conditions by applying good engineering judgement, and amend Annex B8, para. 4.2.2. to modify the charge-depleting fuel efficiency calculation formula for OVC-HEVs and OVC-FCHVs under Level 1B, incorporating treatment of zero fuel consumption cases. The amendments prevent invalid calculations and ensure robustness of WLTP-based methods, addressing limitations in exhaust gas analysis equipment that cause cycle “n” to contain mixed Charge Depleting and Charge Sustaining operation.

Proposal to amend para. 6.1.10. to address division by zero in formulas when an OVC-HEV consumes zero fuel under charge-depleting conditions, and amend Annex B8, para. 4.2.2. to modify the charge-depleting fuel efficiency FECD calculation formula for OVC-HEVs and OVC-FCHVs under Level 1B and 3-phase WLTP testing in Level 2. The amendment applies good engineering judgement optionally to add a dash rather than zero when data input justifiably leads to division by zero.