December 2025: New Standards for Road Traffic Noise Reduction Released

In December 2025, the field of metrology and measurement took a significant step forward with the release of five pivotal standards devoted to the acoustic performance of road traffic noise reducing devices. These newly published specifications—covering sound absorption, airborne sound insulation, and sound diffraction—are set to transform how roadway environmental noise is managed, measured, and mitigated. For industry professionals and compliance officers, these updates signal a move toward higher precision in noise abatement, clearer methods for proving compliance, and greater certainty in long-term product performance.

Overview / Introduction

Metrology and measurement play a crucial role in managing physical phenomena, particularly in environments with rigorous regulatory and community expectations—such as road traffic noise. Roadside noise management not only contributes to public health but also affects property values, urban planning, and infrastructure development.

International standards enable organizations and engineers to:

• Ensure fair competition with transparent acoustic performance benchmarks
• Implement consistent, repeatable test methods
• Demonstrate compliance with national and regional regulations

This article covers the first part in a five-part series, focusing on five new standards published in December 2025. Readers will learn:

• The scope and key requirements of each standard
• Who should comply
• Technical changes and what they mean in practice
• Industry implications and steps toward effective adoption

Detailed Standards Coverage

EN 1793-1:2025 - Sound Absorption under Diffuse Sound Field Conditions

Road traffic noise reducing devices – Test method for determining the acoustic performance – Part 1: Intrinsic characteristics – Sound absorption under diffuse sound field conditions

EN 1793-1:2025 sets out laboratory procedures to assess the intrinsic sound absorption characteristics of road traffic noise reducing devices under reverberant (diffuse) acoustic conditions. Devices must be capable of being assembled inside the test facility (as described in EN ISO 354), and results focus strictly on material performance apart from in-situ installation factors.

Key requirements:

• Laboratory testing using a reverberation room to simulate a diffuse sound field
• Measurement of the sound absorption coefficient across 1/3-octave bands (100 Hz – 5 kHz)
• Calculation of a single-number rating (DL_α,NRD)
• Mandatory measurement uncertainty analysis per ISO/IEC Guide 98-3 and EN ISO 12999-2

Target sectors:

• Noise barrier manufacturers
• Road authorities and consultants
• Environmental engineers
• Testing laboratories

Practical implementation: Lab-based methods help specify the most effective absorber materials for roadside applications in reverberant conditions (e.g., tunnels, deep trenches). The 2025 revision brings:

• Additional guidance on uncertainty declaration
• New terms and definitions
• Improved test report templates

Key highlights:

• Focused on intrinsic properties—not site performance
• Requires advanced understanding of laboratory setups
• Latest revision mandates uncertainty declaration for all test reports

Access the full standard:View EN 1793-1:2025 on iTeh Standards

EN 1793-2:2025 - Airborne Sound Insulation under Diffuse Sound Field Conditions

Road traffic noise reducing devices – Test method for determining the acoustic performance – Part 2: Intrinsic characteristics – Airborne sound insulation under diffuse sound field conditions

This standard introduces laboratory methods for determining the airborne sound insulation performance of road traffic noise reducing barriers under reverberant (diffuse) field test conditions. It supersedes previous editions (notably EN 1793-2:2018) and provides a clear, repeatable baseline for manufacturers and regulators.

Scope & requirements:

• Testing must use EN ISO 10140-2 and EN ISO 10140-4 test facilities
• Specimens assembled to accurately represent in-field construction, including real post-panel interfaces
• Reporting of sound insulation indices (across 100 Hz – 5 kHz) and calculation of a single-number rating (DL_R)
• Measurement uncertainty analysis is now compulsory

Who must comply:

• Manufacturers and labs working with highway noise barriers
• Road operators in densely built urban environments
• Consultants certifying new or replacement installations

Practical implications: Results obtained allow product selection before field-build, important for tunnels, deep cuttings, and other reflective environments. The 2025 update dismisses previous performance ‘categories’ and focuses on numerical ratings, enhancing comparability.

Key highlights:

• Obligates documentation of test setup details and uncertainty
• Realistic representation of road barrier assembly increases reliability
• Focused on reverberant (not open road) scenarios

Access the full standard:View EN 1793-2:2025 on iTeh Standards

EN 1793-4:2025 - Intrinsic Sound Diffraction

Road traffic noise reducing devices – Test method for determining the acoustic performance – Part 4: Intrinsic characteristics – Intrinsic sound diffraction

Addressing a specialized but critical aspect, EN 1793-4:2025 describes the procedures for measuring the sound diffraction performance of devices added to the tops of roadside barriers. This standard compares acoustic performance with and without the added device (e.g., diffusers, toppers) to quantify their benefit, in both in-situ and laboratory (indoor) conditions.

Scope and specifics:

• Prescribes sound pressure level comparisons at reference points near the barrier top edge
• Results reported as sound diffraction index difference (DL_ΔDI)
• Measurements span 1/3-octave bands (100 Hz – 5 kHz)
• Can be used pre-installation (qualification), post-installation (verification), and for long-term durability tracking

Applicable organizations:

• Barrier designers and accessory manufacturers
• Infrastructure owners evaluating product upgrades
• Labs specializing in acoustic diagnostics

Implementation implications: Allows for real-world and lab assessment, making it valuable throughout the product lifecycle. The revised edition updates key terms, reporting, and measurement procedures.

Key highlights:

• The only international standard quantifying diffraction from added devices
• New indoor measurement guidance in Annex D
• Essential for projects adding screens, diffusers, or aerodynamic toppers

Access the full standard:View EN 1793-4:2025 on iTeh Standards

EN 1793-5:2025 - Sound Absorption under Direct Sound Field Conditions

Road traffic noise reducing devices – Test method for determining the acoustic performance – Part 5: Intrinsic characteristics – Sound absorption under direct sound field conditions

This standard details in-situ and lab methods for evaluating sound absorption qualities of roadside noise reducing devices under direct sound field conditions (such as open roadsides, not tunnels). The focus is on the sound reflection index and subsequent calculation of a single-number sound absorption rating (DL_RI).

Scope and key requirements:

• Intended for typical on-road installations and relevant sample sections
• Enables product qualification, post-installation verification, and repeated long-term performance checks
• Requires measurement across 1/3-octave bands (200 Hz – 5 kHz)
• Excludes reverberant environments

Key audiences:

• Manufacturers of roadside and urban noise barriers
• Highway authorities managing maintenance or retrofits
• Testing contractors measuring compliance with environmental standards

Practical implications: By relating absorption performance directly to real-world open-air settings, this standard is crucial for ensuring specified results align with actual conditions faced after installation. The latest edition includes updated reporting templates, expanded annexes, and sharper guidance on measurement uncertainty.

Key highlights:

• Provides a ‘field-realistic’ measure of absorption
• Ensures rigorous performance validation after installation
• Mandates reporting uncertainty and limiting frequency ranges

Access the full standard:View EN 1793-5:2025 on iTeh Standards

EN 1793-6:2025 - Airborne Sound Insulation under Direct Sound Field Conditions

Road traffic noise reducing devices – Test method for determining the acoustic performance – Part 6: Intrinsic characteristics – Airborne sound insulation under direct sound field conditions

EN 1793-6:2025 describes the test method for quantifying the intrinsic airborne sound insulation of roadside noise barriers as installed, or in realistic laboratory settings, using direct sound field techniques. The outcome is the ‘sound insulation index’ as a function of frequency—giving a robust basis for product specification and regulatory reporting.

Key requirements:

• Flexible for both lab and on-site measurements
• Applies to products as-installed, checked immediately post-construction or during long-term confirmation
• Covers 1/3-octave bands (200 Hz – 5 kHz) for qualification
• Employs a grid of nine measurement microphones (a notable update from earlier versions)
• Requires comprehensive documentation of measurement uncertainty

Who benefits:

• Infrastructure owners demanding certifiable, traceable performance
• Consultants involved in product approval or dispute resolution
• Manufacturers and testing bodies ensuring product development aligns with evidenced field performance

Practical effects: This method ensures that laboratory and on-site measurements can be correlated and trusted, facilitating design, maintenance, and product innovation for noise insulation on open roads (not in reverberant environments).

Key highlights:

• Direct field testing bridges the gap between lab predictions and real-world results
• New measurement approaches improve repeatability and reliability
• Supports both product innovation and lifecycle management

Access the full standard:View EN 1793-6:2025 on iTeh Standards

Industry Impact & Compliance

The December 2025 suite of standards ushers in a new era of clarity for road traffic noise control. Rigorous, harmonized methods significantly:

• Reduce the risk of project non-compliance and legal challenge
• Enable more robust procurement and comparison of products
• Enhance community confidence in infrastructure projects

Compliance considerations:

• Many national and regional authorities reference these standards for infrastructure projects
• Declaration of measurement uncertainty is now mandatory—a key point for accredited labs and manufacturers
• Transition timelines may apply; early adoption will provide a competitive edge

Benefits:

• Certainty in product selection and specification
• Improved accountability and traceability in performance reporting
• Better long-term monitoring and maintenance planning

Risks of non-compliance:

• Regulatory penalties or remedial project work
• Erosion of public trust and potential legal disputes
• Lost bids for infrastructure contracts

Technical Insights

A few technical themes recur across these five standards:

• Test Methodology: Laboratory (diffuse) methods suit tunnels and enclosed settings, while direct field tests serve open roads. Each standard mandates clear reporting, calibration, and equipment requirements.
• Frequency Coverage: All standards stipulate measurement in 1/3-octave bands, but lower frequency cutoffs vary based on perceived real-world relevance (100 Hz–5 kHz or 200 Hz–5 kHz).
• Measurement Uncertainty: Compulsory calculation and reporting—using frameworks from ISO/IEC Guide 98-3—ensure end-users have confidence in published data.
• Product Lifecycle: Standards support design phase (qualification), procurement, post-installation verification, and repeated performance checks for long-term assurance.

Implementation best practices:

1. Always assess site conditions before selecting the appropriate method (reverberant vs. direct)
2. Use accredited testing labs familiar with updated uncertainty requirements
3. Integrate test results into digital asset management systems for easier monitoring
4. Schedule periodic retesting to verify long-term compliance

Testing and certification:

• Engage with notified bodies early in the project cycle
• Prepare to supply detailed reports, including measurement uncertainty
• Ensure installation replicates laboratory setup as closely as possible for consistent results

Conclusion / Next Steps

The December 2025 release of five key standards for road traffic noise reducing devices marks a definitive advancement in the measurement and management of physical acoustic phenomena on roadways. For infrastructure professionals, these documents provide a foundation for compliance, product differentiation, and public trust.

Recommendations:

• Review the full text of each standard to understand the nuances relevant to your projects
• Update internal protocols to reflect new testing and reporting requirements
• Train staff on uncertainty analysis and the importance of method selection
• Plan early for compliance—especially for major project bids in regulated markets

Explore the new standards in full and stay informed with iTeh Standards: standards.iteh.ai

Stay tuned for Part 2 of our coverage, where we continue exploring December 2025’s instrumental updates in Metrology and Measurement standards.