Meeting minutes documenting PMP discussions on amendments to Brakes GTR 24 and UN R179, including TF3a layout and testing topics, TF3b vehicles limited speed work, TF3c brake replacement parts with a new UNR to be introduced, and TF4 electromechanical brakes with no further progress. GTR and UNR informal documents on HD brakes were presented with trailers removed from scope, open points on PM Emission Factor units, caliper position, test input parameters, and cooling air flow value addressed, and a 3-month delay in round robin testing reported.

Overview of working documents for the 95th session of GRPE, listing five working documents on new GTR for heavy-duty brake emission, UN R179 second supplement, GTR 24 third amendment, vehicles with limited speed for UN R179 and GTR 24, and new UNR on emissions covering brake replacement parts, with informal documents to follow from clean working documents.

Agenda for a PMP webex meeting on 29 September 2026 to review meeting minutes, overview amendments to GTR 24 and UN R179 on brakes across multiple task forces covering layout and testing topics, vehicles limited speed, brake replacement parts, and electromechanical brakes, discuss GTR and UN R heavy-duty brakes, and address any other business.

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 modify UN GTR No. 24 with respect to laboratory measurement procedures for brake emissions of light-duty vehicles. This amendment improves and corrects the testing procedure, including detailed requirements for test system setup, cooling air conditioning, brake dynamometer specifications, WLTP-Brake cycle execution, emissions measurements for particulate matter (PM2.5, PM10) and particle number (TPN10, SPN10), calibration protocols, and reporting of results. The regulation defines brake corner emissions families, friction braking share coefficients for different vehicle electrification types (ICE, HEV categories, PEV), and test procedures using fully-enclosed brake dynamometers with isokinetic sampling systems. A version with tracked changes is available.

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.

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.

Proposal to amend UN GTR 24 (Laboratory Measurement of Brake Emissions for Light-Duty Vehicles) by clarifying requirements for electromechanical brakes and dry brakes, modifying test procedures, updating definitions and technical specifications, revising cooling airflow adjustment methodologies, refining PM and PN measurement protocols, and adjusting calibration intervals and quality control procedures.

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 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.

The PMP session discussed revisions to the group’s terms of reference to address overlapping technical issues with GTR 24, UN R179, and replacement parts regulations. Three task forces were proposed: TF3a on layout and testing, TF3b on speed-limited vehicles, and TF4 on electromechanical brakes. Topics included non-original brake parts regulations, UN R179 amendments for new vehicle categories, and GTR heavy-duty brake particle emissions standards. The next meeting was scheduled for end of April 2026.