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 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 include testing of vehicles with limited speed. The document sets out the laboratory measurement procedure for brake emissions from light-duty vehicles of categories M₁ and N₁, including vehicles with maximum speed below the Base cycle maximum speed. Testing involves three sections: cooling air adjustment, brake bedding with five repetitions of the WLTP-Brake cycle, and brake emissions measurement with one WLTP-Brake cycle. Brake corner emission families are tested on a component test bench under full-friction braking conditions, measuring PM₁₀ and SPN₁₀ emissions. Compliance is demonstrated using brake corner emissions family parents. Conformity of production requires monthly sampling and testing of brake components, with results evaluated using statistical decision charts through 31 December 2029 for PM₁₀ and thereafter for both PM₁₀ and SPN₁₀.

Proposal to insert new paras. 3.3.29. to 3.3.33. defining “Semi-Metallic-Organic,” “Low-Steel-Organic,” “Non-Asbestos-Organic,” and “Low-Steel-Non-Organic” friction materials and “Pad area,” amend Annex 2 title to read “Annex 2 Communication,” insert a new footnote to Annex 2, and insert a new Annex 2 – Appendix containing a list of vehicle data for UN Regulation No. [XXX] approvals including vehicle type description, brake linings and discs specifications, vehicle test mass, maximum speed, tyre dimensions, brake circuit configuration, and brake specifications.

Task Force 3b addresses vehicles with limited speed by introducing a new Appendix 3 in Annex 4 to calculate adjusted cycles when vehicle maximum speed is lower than the WLTC-Brake cycle. The proposal modifies brake corner emissions family testing to allow vehicles with limited speed to be included in families with standard vehicles, with emission factors calculated from parent family factors or measured on adjusted cycles. Amendments address c-factor measurement, cycle-adjusted brake events, kinetic energy dissipation tolerances, and report file specifications.

Proposal to amend UN R179 following GRPE-94-15e:

• Include supplements on automated vehicle definitions and OICA proposals on family members with higher wheel load but lower wheel load times c-factor ratio,
• Clarify wheel load and vehicle mass definitions for different tests,
• Add wheel load distribution for light commercial vehicles with fully laden mass between 3.5 and 5 tonnes,
• Redefine brake assembly to allow brake calliper reuse if in technically suitable condition,
• Optionally omit cooling air adjustment if temperature requirements are fulfilled,
• Require three emission measurement sections instead of one for type approval with arithmetical average reported,
• Clarify energy calculation for vehicles with limited speed,
• Harmonize reporting requirements including units and decimals,
• Define normalized flows,
• Include transitional provisions stating that vehicle types with existing valid type approvals issued before entry into force of supplement 2 need not undergo new type approval testing.

TF 3c addressed brake emission of replacement parts. Proposed amendments include clarification that surface heat-treated discs fall under “other” category, refinement of “Brake Emissions Family Parent” definition, and addition of new appendix to UN Regulation No. 179 Annex 2. Data sharing agreement established: front-to-rear axle emission ratio, brake force distribution, and vehicle electrification type will be shared with aftermarket operators. Two approaches for aftermarket applicants: use vehicle-specific data through benchmarking or bilateral agreements, or apply default values from Tables 5.4 and 5.5. Testing revealed up to 30% variation within friction-couple families. Safety factor application when using actual c-factor values remains under discussion, with final decision expected before October.

Task Force 4 has completed revisions to GTR 24 concerning electro-mechanical calipers and proposes to include them in Amendment 3.

Draft Minutes of the 56th Particle Measurement Programme session held online on 9th July 2026, 12:00-14:30 CET. The meeting reviewed amendments to Brakes GTR 24 and UN R179 across five task forces. TF3a presented layout and testing topics with concerns raised regarding repetition increases and force distribution. TF3b discussed vehicles with limited speed and family classification issues. TF3c addressed brake replacement parts and emission limits. TF4 reported on electromechanical brakes with work package B agreed. TF5 presented the GTR on heavy-duty brake particle emissions with results expressed in mg/km, with some points remaining in brackets pending inter-laboratory comparisons. Comments are due by 16th July, with the next meeting expected mid/end of September 2026 and a hybrid PMP meeting planned for 12th or 13th October in Geneva.

PMP webex meeting scheduled for 9th July 2026, 12:00–14:30 CET. Agenda includes an overview of amendments to Brakes GTR 24 and UN R179, task force discussions on layout and testing topics, vehicles limited speed, brake replacement parts, electromechanical brakes GTR and UNR, HD brakes, projects on tyres and brakes, and any other business. Webex meeting access details and link provided.

The 56th PMP session convened online on 7 May 2026 with approximately 70 participants. Meeting minutes from 13 March 2026 were accepted. PMP agreed on a joint neutral template for all task forces. TF3a discussed cooling air adjustment, temperature criteria, and vehicle emission factors, with proposals requested by end of May 2026. TF3b will discuss family building and speed-limited vehicles. TF3c presented brake replacement parts activities. TF4 prepared work package B on electromechanical brakes and requested feedback by end of May 2026. TF5 reported progress on GTR on HD brake particle emissions with test campaigns planned. The next meeting is expected end of June or beginning of July 2026.

Task Force 4 addresses brake system development towards dry brakes, specifically electromechanical brakes. Current methods to determine friction brake torque available for hydraulic systems are not all applicable for dry systems. Task Force 4 targets defining a pressure-based equivalent method for electromechanical brake systems and reviewing document validity for electromechanical braking systems. Work Package B completed text document review with proposed changes due end of May 2026. Work Package A discusses two alternative approaches for c-factor calculation: clamping force based and recuperated energy based, with verification tests planned by end of June 2026.

PMP Task Force 3b held kick-off on 07.05.2026 to address vehicles with legal limited speed, vehicles unable to follow cycle trace, and vehicles with capped speed by OEM decision. Proposals include adaptation of UN R179 cycle and procedure for vehicles with legal limited speed at 90 kph, with same duration for acceleration, cruise, and deceleration events, same acceleration and deceleration rates, and speed capped when needed. Introduction of such vehicles into brake corner emission families and vehicle types requires methodology to calculate adapted cycle and procedure, including c-factor measurement as alternative to fixed c-factor, and adaptation of Annex 5 procedure.

PMP TF 3a is consolidating and updating UN R179 and GTR 24 through weekly web-meetings organized by JRC with 30+ participants. Over 50 topics have been identified and categorized by priority. Key issues include aligning Type Approval and Conformity of Production testing procedures, harmonizing cooling air adjustment requirements, clarifying vehicle c-factor calculations, adding definitions for light-duty vehicles exceeding 3.5 tonnes, and addressing test wheel load per GRPE-94-15e. The task force is preparing track changes versions and supporting documentation for major changes.

The PMP webex meeting scheduled for 7 May 2026, 12:00-14:30 CET will review meeting minutes from 13.03.2026, provide an overview of amendments to Brakes GTR 24 and UN R179 covering layout and testing topics, vehicle limited speed, brake replacement parts, and electromechanical brakes, discuss GTR HD brakes, and address any other business.

Proposal to amend UN R179 Supplement 1:

• Modify the scope to include vehicles of category N₂ between 3.5 and 5 tonnes maximum mass at manufacturer request
• Add abbreviations and definitions including “Category M₁ vehicle”, “Mass in running order”, “Service brake”, “Brake calliper”, “User-selectable mode”, “ADS user”, and “Vehicle user”
• Amend the reference method to require testing on WLTP-Brake cycle using UN R154 compliant chassis dynamometer with external sensors for brake torque
• Specify vehicle selection procedures for testing user-selectable modes resulting in lowest recuperation with possible exemptions for very special limited purposes modes