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.

The 22nd session of the Task Force on Vehicles Sound will convene on Tuesday 1st September 2026 from 9:00 to 11:30 (CEST) as a hybrid meeting in Geneva. The agenda includes a cross-matrix comparison on approaches to sound traffic modelling, discussion on updating the guidelines of the Task Force as approved at GRBP-74 in September 2021, any other business, and confirmation of the next meeting provisionally scheduled for 20th October 2026 in Barcelona.

The Task Force Vehicles Sound Cross Matrix activity requests input on traffic sound models. Volunteer participants are invited to share information on noise mapping models used in their regions, including model name, year of last update, references, source descriptions, number of vehicle classes, vehicle class descriptions, formulas and parameters for each class, reference roads for tyre rolling sound, comparison to ISO 10844:2021 type approval test tracks, and propagation concepts used.

Two presentations addressed road traffic noise: NEFOM presented findings on the gap between type-approval motorcycle noise levels and real-world noise exposure, noting that roadside measurements show motorcycles can generate noise approaching 100 dB(A) and that 20% of vehicles appeared tampered. A University Medical Center Mainz presentation highlighted scientific evidence that traffic noise contributes to cardiovascular, metabolic, neurological, and sleep-related disorders affecting over 130 million Europeans. Discussion noted the importance of reducing night-time noise exposure and that stricter UN-R41-06 limits cannot yet be heard in the current fleet. The Cross Matrix topic was deferred to the next session.

sonROAD18 is a Swiss road traffic noise emission model based on CNOSSOS-EU formalism, covering more than 10 vehicle categories with speed ranges 20–130 km/h, calibrated using over 700,000 pass-bys from 2015–2017. NExUS is a research model for noise from battery electric and internal combustion engine passenger cars during acceleration in urban scenarios, based on more than 3,000 real drive trajectories recorded in 2024, with speed ranges 0–60 km/h. Both models predict noise emissions via propulsion and rolling noise components using three octave bands.

This document requests sound model documentation through a series of questions. Two models are documented: sonROAD18, last updated October 2024, uses more than 10 vehicle classes and describes sound power levels using propulsion noise and rolling noise components with spectral model coefficients, vehicle speed, road gradient corrections, pavement corrections, and air temperature corrections. The reference pavement is ACMR8 with porosity less than 8%. NExUS, last updated 2025, uses two vehicle classes comparing battery electric vehicles and internal combustion engine passenger cars, describing sound power levels using spectral model coefficients, speed, and acceleration parameters. The reference pavement is dense asphalt concrete AC 11 S. Both models use omnidirectional directivity and position sources 0.05 m above road surface.

Report of the 22nd session of TF-VS held on 1 September 2026. The session focused on cross-matrix activity for road traffic noise, with presentations on Swiss sound emission models sonROAD18 and NExUS developed by the Federal Office for the Environment. sonROAD18 is a general road traffic noise prediction model based on CNOSSOS-EU framework used for sound mapping in Switzerland since 2023. NExUS is a research model for comparing noise emissions of electric vehicles and internal combustion engine vehicles based on pass-by measurements. France, Sweden, Japan, Germany and The Netherlands proposed to present their own approaches at future sessions.

Policy briefing addressing road traffic noise as a public health hazard and environmental concern. Documents adverse health effects of chronic noise exposure including cardiovascular disease, sleep disturbance, and cognitive impairment affecting over 100 million people. Identifies single-event noise exposures from modified combustion vehicles as disproportionately harmful drivers of citizen complaints. Warns that Enhanced Exterior Sound (EES) systems in electric vehicles replicate these harmful characteristics through high peak levels, steep onset rates, and prominent low-frequency tonal content. Recommends prohibiting EES designed to create sounds unrelated to safety, regulating Acoustic Vehicle Alerting Systems (AVAS) to minimum levels necessary for pedestrian safety while ensuring sound quality accessible to vulnerable populations, employing supplemental metrics beyond A-weighted averages to characterize harmful exposures, and making harm reduction an explicit objective of vehicle sound regulation.

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.

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.