Replies to comments from ETRTO and OICA on the LEON-T study.

The Cross Matrix activity began with TFSL-02-07 (May 2021) defining the concept to assess regulation effects across different areas. TFVS-04-14 (Sep. 2021) clarified building a sound model. Early work 2021-2022 defined traffic and fleet scenarios through TFVS-05-06, TFVS-06-03, TFVS-07-08, and TFVS-06-05, which selected eight scenarios from residential areas to motorways. Activity decreased by 2023, with TFVS-12-06 calling for resumption. TFVS-17-07 compared model results from EU, Switzerland, Japan, and HMG Akustiklabor. Future steps include addressing L_max, traffic measure effects, opening the approach to L categories, and assessing progress from new RD-ASEP in UN R41 06 series.

This presentation reviews the consideration of cross matrix modules to enable GRBP and subgroups to evaluate regulation amendment proposals regarding their impact on real world traffic. The cross matrix addresses how vehicle sound emission regulations influence sound levels considered by road traffic noise models. Four existing sound source models are compared: EU CNOSSOS, SonRoad18, CNOSSOS JP, and HMG ASJ RTN. HMG sound power models derived from pass-by data on ISO 10844 compliant test tracks evaluate EVs and include type approval data for ASEP and RD-ASEP. Statistical pass-by simulations using randomized vehicle selection enable calculation of LA, eq for traffic scenarios with varying fleet compositions. To advance this work, sound power models for missing UN R51.03 and UN R41 vehicle categories, especially buses and trucks and new propulsion technologies, must be created and reference scenarios established and agreed upon.

The 21st session of the Task Force on Vehicles Sound will be held on Tuesday 9th June 2026 from 13:00 to 17:00 (CEST) as a hybrid meeting in Gothenburg, Sweden. The agenda includes adoption of the agenda and report of the 20th session, exchange of information on national and international requirements with presentations on anoise figures in vehicle certificates of conformity versus perceived noise" and on “transportation noise and cardiovascular health”, cross-matrix follow-up discussion, discussion on updating the guidelines of the task force as approved in GRBP-74-03 Rev.1, any other business, and determination of next meeting and provisional agenda.

NEFOM and S.O.S. represent over 1 million European citizens experiencing noise from light vehicles inconsistent with Certificate of Conformity figures. The LENS project conducted 2300 measurements of 2300 vehicles, finding measured noise levels in practice much higher than type approval, sometimes reaching 100 dB(A). The A-filter used in Certificates of Conformity is unsuitable for noise levels above 70 dB and does not represent human perception. Sound limits for motorcycles have not changed since 2015 and remain too high. The document requests further improvements to RD-ASEP testing, replacement of the A-filter with a C-filter, and significant reduction of sound level limits for motorcycles.

During the 19th session

• OICA commented on LEON-T project reports regarding tyre and powertrain noise contributions.
• The European Environment Agency presented findings on transport noise exposure affecting over 100 million Europeans.
• Norway presented a proposed 95 dB(A) noise limit for stationary vehicles under UN R51.
• France proposed amending UN R28 to introduce soft audible warning devices for M and N category vehicles.
• The task force suspended its cross-matrix activity and postponed discussion of L-category vehicles to the next session.

The 20th session of the Task Force on Vehicle Sound convened on 14 April 2026. The session adopted the draft agenda and reviewed the 19th session report with a minor correction. The cross-matrix, defined in 2021 to assess traffic noise reduction policies through traffic scenarios and models, was rediscussed. A model based on RD-ASEP monitoring data was presented, showing significant deviations from EU-CNOSSOS predictions. Additional data are needed for M₃/N₃ and L-category vehicles. Extension of the cross-matrix to L-categories was proposed, utilising data from UN R41-06 RD-ASEP. A subgroup was established to develop scenarios, particularly for L-categories, and review available models. The next meeting is scheduled for 9 June 2026.

Over 130 million people are affected by transportation noise, an important risk factor for disease burden. Road traffic noise increases cardiovascular risk by approximately 3.2% per 10 dB increase and all-cause mortality risk by approximately 5.5%. The WHO road-noise guideline of 53 dB Lden may not be sufficiently protective, as mortality risk increases at lower noise levels. Night-time noise increases blood pressure and is associated with increased use of sleeping medication. Aircraft and road traffic noise can increase blood pressure, disturb its normal daily rhythm, and contribute to hypertension. Reducing residential noise exposure should become part of cardiovascular prevention.