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This document proposes a new UN Global Technical Regulation (UN GTR) for measuring brake particle emissions from Heavy-Duty Vehicles (HDVs). The GTR establishes a harmonised laboratory methodology covering the Worldwide Harmonised Heavy-Duty Vehicles Brake Cycle (WHBC), test system requirements, and measurement protocols for particulate matter (PM) and particle number (PN) emissions.
Key substantive elements include:
- Scope covering M2–M3, N2–N3, and O3–O4 category vehicles with friction braking systems
- Detailed specifications for brake dynamometer systems, enclosure design, sampling tunnel geometry, and cooling air conditioning
- Definition of the WHBC comprising three segments (urban, rural, motorway) with 246 brake events over 20,353 seconds and 271 km
- Brake bedding procedure (six consecutive WHBC cycles) followed by a single WHBC emissions measurement section
- Requirements for PM10 and PM2.5 gravimetric sampling using cyclonic separators and filter-based collection
- Requirements for TPN10 and SPN10 measurement using dilution systems and particle number counters with specified PCRFs
- Detailed quality checks including speed violations, brake event count verification, and kinetic energy dissipation tolerances
- Comprehensive calibration requirements for dynamometer, flow measurement, weighing equipment, and sampling/measurement devices
- Test output specifications including Event-Based, Time-Based, Mass Measurement, and Test Report files
The regulation applies a friction braking share coefficient to convert reference emission factors from the tested brake to final emission factors applicable to the vehicle.
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