Noise barriers and acoustic screens: issues, regulations and implementation

Regulatory context and obligations of project owners

The fight against infrastructure noise is governed by a dense regulatory framework. The law of December 31, 1992 on noise abatement lays the foundations for national policy. It is supplemented by European Directive 2002/49/EC, transposed into French law, which requires major conurbations and infrastructure managers to draw up environmental noise prevention plans (PPBE).

For roads and railroads, the regulations set noise exposure limit values according to the category of infrastructure and the sensitivity of the neighboring areas. The noise classification of roads, provided for in the decree of May 30, 1996, determines the sectors affected by noise and the soundproofing requirements applicable to new constructions. Where existing dwellings are exposed to excessive levels of noise, the installation of a noise barrier can be a compulsory or voluntary remedial measure.

Public project owners – local authorities, network operators – and private developers and manufacturers – must demonstrate that their projects comply with regulatory thresholds. A preliminary noise impact assessment is often required as part of environmental impact studies or building permit applications.

What sources of noise pollution are involved?

Exterior acoustic screens can be applied to a wide variety of sources. Transportation infrastructures account for the majority of projects: national roads and freeways, high-speed railroads, bypasses and urban ring roads generate continuous noise levels that frequently exceed admissible thresholds in residential areas.

Noisy industrial sites are another major use case. Installations classified for environmental protection (ICPE) are subject to strict acoustic regulations, defined in particular by thedecree of January 23, 1997 and its sectoral decrees. When emissions at the property boundary exceed authorized emergence values, a sound barrier may be required to achieve regulatory compliance.

This also applies to shopping areas, logistics platforms, airports and port infrastructures. In these contexts, prior acoustic measurement enables us to precisely characterize the source, identify the dominant frequencies and size the screen accordingly.

Function and types of acoustic screens

A noise barrier acts as a mask: it places a physical obstacle between the sound source and the receiver, creating an acoustic shadow zone. The effectiveness of the screen depends on several parameters: its height in relation to the two ends of the sound path, its length, its inherent sound attenuation index and the nature of the surrounding ground.

The materials used vary according to project constraints. Precast concrete offers high soundproofing performance and recognized durability. Wooden or composite panels are more suited to landscape-sensitive environments. Transparent screens – in glass or PMMA – are preferred when visibility is a constraint, particularly in dense urban environments.

The effective height of a screen is calculated from the acoustic step difference, a central concept in building and environmental acoustics. A poorly dimensioned screen – too short or too low – will produce only marginal attenuation, without meeting regulatory requirements. This is why dimensioning cannot be based on rules of thumb alone: it requires rigorous acoustic simulation.

Acoustic study and sizing: the design office’s approach

SIM Engineering intervenes upstream of projects to establish a complete acoustic diagnosis of the existing situation. This phase includes on-site acoustic measurement campaigns, carried out in accordance with current standards, as well as sound propagation modeling using certified software. Exposure levels are mapped, enabling critical areas to be identified and precise reduction targets to be set.

The design office then defines the technical characteristics of the screen: height, length, materials, required sound attenuation index. The chosen solution is validated by acoustic simulation, taking into account the effects of diffraction at the top of the screen, reflection on neighbouring surfaces and meteorological conditions. A detailed acoustic report is submitted, including calculation hypotheses, results obtained and construction recommendations.

SIM Engineering also assists project owners in the acceptance phase: post-construction acoustic measurements verify the actual effectiveness of the screen and certify compliance with the objectives set. This acoustic monitoring approach guarantees traceability of performance and secures the owner’s responsibility.

Conclusion

Noise barriers are a proven technical response to noise pollution generated by infrastructure and industrial activities. Its effectiveness depends entirely on the quality of the preliminary acoustic study: field measurements, numerical simulation and standardized dimensioning. SIM Engineering, an acoustic design office, assists clients, local authorities and manufacturers at every stage of their exterior acoustic insulation projects. For all your outdoor noise problems, contact SIM Engineering for an analysis tailored to your situation.

See our noise barrier guide.