Presentation comparing results of Switzerland’s NExUS study on electric vehicles and internal combustion engine vehicles with RD-ASEP Sound Expectation Model predictions. NExUS study objective was to compare EVs with ICE vehicles of the same consumer segment to better understand EV modelling. Key findings show overall sound levels of EVs and modern ICEs are close under constant speed, while ICE sound is higher under low-speed acceleration. RD-ASEP SEM predictions align closely with NExUS measurements for both accelerated and constant speed conditions.

Document presents comparison of UN R51.03 ASEP, UN R51.04 RD-ASEP, and an updated ASEP alternative concept. It outlines improvements including explicit testing of all conditions to reduce test detection schemes, expanded vehicle speed range to 1-100 km/h, random test point evaluation, and extension to part load conditions. Main open topics include tyre model stability, technology and model temperature correction, application and uncertainties, and criteria and judgement safeguards. Document identifies quick wins through clarification that all modes must be tested and suggests main improvements can be realized through an updated, simple ASEP with part load testing capabilities.

Presentation on the Nord2000 noise model used in Sweden for road traffic noise mapping. Nord2000 uses five vehicle categories described by weight and number of axles, with 1/3 octave band frequency resolution from 25 to 10000 Hz. Two sources per vehicle category represent rolling and propulsion mechanisms. The model includes surface corrections based on Swedish CPX measurements, horizontal and vertical directivity patterns, and methods for deriving source sound power levels from field measurements using the propagation model with assumed omnidirectional sources.

Study identifying and prioritizing road traffic parameters that most strongly influence linear acoustic power levels and noise exposure using the European regulatory method CNOSSOS-FR in the Hauts-de-Seine department. Sensitivity calculations applied to 25 of 36 municipalities using E5 parameters, with population exposure counted using the median method. Analysis examines hourly traffic composition, pavement data from Renault sensors collected June 2024 to May 2026, and average speed data from departmental and national sources.

Policy briefing on road traffic noise as a health hazard and the opportunity for electric vehicles to reduce environmental noise pollution. Documents health impacts including hearing loss, cardiovascular disease, cognitive impairment, and sleep disruption, with particular vulnerability for infants, children, seniors, and people with pre-existing conditions. Addresses enhanced exterior sound systems in EVs that replicate combustion engine noise, undermining noise reduction benefits. Recommends regulating acoustic vehicle alerting systems for pedestrian safety while prohibiting sounds beyond public safety requirements, and prioritizing public health over commercial preferences.

Overview of rounding principles for calculations in models where results are used for further calculation. Recommends carrying full precision until the end and applying rounding only to final output. Identifies Round Half to Even as standard for modeling and statistics, and Round Half Up as used in UN Regulations. Advises matching output precision to input data uncertainty and not reporting more precision than input data warrants.

Task Force Data Analysis provides input to the Editing Task Force on three items. For vehicles with single gear ratios, remove brackets from text restricting acceleration to no more than 2.0 m/s and continue with adopted text for UN R51.04. Restructure Annex 7 paragraph 4.4. into subparagraphs for clarity. Rework paragraph 3.6.1. to define reference acceleration with v-t-e ratio and specify procedures for determining maximum reference acceleration. Add specification to factor x determination to prevent extreme results and harmonize its representation as either percentage or decimal value.

Agenda for the 23rd session of the Task Force on Vehicles Sound on 20 October 2026. The session will cover adoption of the agenda and report of the 22nd session, exchange of information on national and international requirements including presentations on quiet communities and noise sensitivity analysis, cross-matrix comparison of sound traffic modelling approaches with presentations on noise modelling and CNOSSOS-FR parameters, any other business, and arrangement of the next meeting in February 2027.

Meeting minutes from the GRBP Informal Group RD-ASEP held August 31–September 2026 in Berlin, Germany. The group reviewed the status report to GRBP, an issues list, and draft text for UN R51.04. OICA presented a document on the sensitivity of RD-ASEP results and difficulty of assessing worst case vehicle. The Secretary presented updated terms of reference to GRBP for approval. Experts are requested to submit all documents a minimum of 7 days prior to any IWG meeting date.

Proposal to establish revised terms of reference for the IWG RD-ASEP covering vehicles of categories M₁, N₁, and L₃. The group shall modify current regulations to mandate revised RD-ASEP, update Annex 9, delete Annex 7 and update relevant paragraphs in the main body and Annex 3 of UN R51, develop limit curves for different riding situations in UN R41-05, consider relevant transitional provisions, and develop coordination between UN R51 and UN R138. The IWG shall be chaired by Germany with OICA as Secretary for M/N categories and IMMA for L category, and shall present a working document for M₁ and N₁ vehicles by February 2028.

Proposal to amend UN Regulation No. 51 on the noise of M and N category vehicles, introducing comprehensive provisions for measuring and limiting sound emissions. The proposal establishes testing methods for vehicles in motion and at rest, defines sound level limits by vehicle category and power characteristics, and introduces Real Driving Additional Sound Emission Provisions (RD-ASEP) for M1 and N1 vehicles to ensure compliance during typical on-road driving conditions representative of urban and suburban traffic. Transitional provisions permit Contracting Parties to continue approving vehicles under preceding series until a specified date.

Report from the Task Force Data Analysis to the Informal Working Group on Real Driving Sound Emissions and Performance (IWG RD-ASEP) covering several technical matters: clarification on restrictions in UN R51 supplement 11 to avoid high noise levels for single-gear vehicles; restructuring of control range specifications in Annex 7; redefinition of maximum reference acceleration for the sound emission model; discretization of factor x determination with consideration of rounding procedures; clarification of AVAS sound level requirements distinguishing between whole-vehicle and component-level interpretations; and temperature correction application for the sound emission model. Further work topics include indoor testing, EV model simplification, and slope considerations.

The agenda includes a review of Terms of Reference from GRBP 78th Session (GRBP-78-13), report of Data Analysis Task Force, review of issues list, review of draft text, and discussion of UN R51 matters. Dates and locations of 2027 meetings will be determined.

Document presents technical challenges to defining retrofit kit types for electric conversion and approval processes. Identifies that retrofit kit type perimeter depends on the regulation considered, with different requirements across UN R10, R13, R100, R85, R138, WLTP, R79, R39, R51, R89, R121, and R122. Presents testing challenges at vehicle, component, and EPRS levels, noting that testing a kit type not installed on a vehicle is impossible to account for all impacts on the vehicle.

Proposal to amend Annex 7, paragraph 2.3.1 to explicitly frame the area of valid values for factor x, requiring that the factor x determined by measurements shall always be at least 0.10 and not exceed the values provided by the parameter table in Appendix 2 to that Annex. The document explains that factor x is used to split constant speed test results energetically into tyre rolling sound and power train mechanic references, and that measurement variations can cause significant variability in calculated values, particularly when factor x exceeds 0.90.

Summary of the Task Force Data Analysis meeting held 29 September 2026. The meeting discussed amendments to factor x for improved model robustness, consideration on LDYN with amendments on factor x, and considerations on the AVAS term to match UN R138. Proposals to the TF-Editing were discussed based on draft UN R51.04, including input from Germany. The Editing TF raised a question regarding the phrase “but no more than 2.0 m/s” in para. 3.1.2.1.4.3 concerning vehicles with only one gear ratio, which was included in Supplement 11 to UN R51.03 to prevent unrealistic kp values. TF-DA suggested proceeding with the adopted text as is.

Proposal to replace the current logarithmic function with a segmented function that linearizes the curve in the unstable area near the clipping boundary. The new formulation uses a tangent line to the logarithmic curve below the tangency point and clips to a minimum value of 10 dB. Two parameters define the tangency and clipping conditions: clipping value of 10 dB and slope of 5 dB per unit. The detailed formulation provides the mathematical definitions of the logarithmic function, the linearized segment, helper variables, and constraints including tangency and asymptote conditions.

Agenda for the 18th meeting of the Task Force Data Analysis, a sub-group to IWG RD-ASEP. The meeting will review and adopt the agenda, discuss the meeting schedule for November and December 2026, continue discussion on necessary amendments to RD-ASEP including LDYN definition, AVAS term alignment with UN R138, temperature correction, indoor testing, simplified EV model with integrated AVAS approach and Supplement 11 amendments, and slopes and parameter table settings. The meeting will review proposals to the TF-Editing and decisions for the next meeting.