EN 14389 Road Traffic Noise Reduction Devices - Procedures for Assessing Long-Term Performance

The European standard “EN 14389 Road traffic noise reduction devices - Procedures for evaluating long-term performance” consists of the following sub-parts published under the same title:

• The standard "EN 14389-1 Part 1: Acoustic properties" describes methods for assessing the acoustic resistance of road traffic noise reduction devices. In this standard, sound absorption is characterized by a single-numbered sound reflection value, as defined in the CEN/TS 1793-5 standard. Airborne sound insulation is characterized by a single-numbered airborne sound insulation value, as defined in the CEN/TS 1793-5 standard.

Roadside road traffic noise reduction devices must not only meet their acoustic function and structural design requirements in accordance with relevant European standards, but also maintain their performance over a reasonably economical operating life. Acoustic elements must be resistant to the effects of factors in the roadside environment that could significantly degrade their performance.

The acoustic properties of a road traffic noise reduction device can deteriorate significantly over its operational life if it is not installed or maintained in accordance with the manufacturer's recommendations, or if the materials used are not suitable for the roadside environment. Until now, no method existed for assessing the durability of the acoustic properties of noise reduction devices. Therefore, new methods have been introduced in CEN/TS 1793-5, as specified in this standard. The use of these methods may produce sound reflection values ​​for noise reduction devices that differ from the sound absorption values ​​obtained from EN 1793-1, which forms the basis for product characterization of absorbent noise reduction devices. These differences should be ignored in product characterization. Sound reflection values ​​obtained from tests conducted in accordance with CEN/TS 1793-5 are used in this standard only as a comparative tool for assessing long-term durability.

For the purposes of this standard, the following definitions apply:

• Structural elements: Elements whose primary function is to support or hold acoustic elements in place.
• Acoustic elements: Elements whose primary function is to ensure the acoustic performance of the device.

In general, the manufacturer must declare the estimated deterioration in acoustic performance after 5, 10, 15, and 20 years of service in specific exposure classes, assuming the road traffic noise reduction device is maintained in accordance with the manufacturer's recommendations. The durability of acoustic properties is assessed by descriptive solutions based on the estimated performance of the materials used, by reference to relevant European material standards, or by comparative performance tests according to CEN/TS 1793-5.

Performance evaluation can be carried out by physical examination or tests according to the CEN/TS 1793-5 standard.

In order to evaluate changes in acoustic properties according to the CEN/TS 1793-5 standard, it is necessary to evaluate the acoustic properties corresponding to the installation service in order to perform the first on-site test.

The manufacturer declares the expected acoustic performance durability of the product under the combination of all typical exposure classes specified in the table in the format shown in the table. If the product's evaluation includes one or more of the specific exposure classes specified in the table, the corresponding durability under each of these conditions is declared in a supplementary table as shown in the table. The acoustic performance durability is expressed in dB as the changes in sound reflection and sound absorption compared to the initial values.

• The standard "EN 14389-2 Part 2: Non-acoustic properties" specifies the requirements for assessing service life and specifies the relevant exposure conditions. Construction standards and all material tests performed must provide evidence of resistance to specified conditions, selected from: chemicals, deicing salt, contaminated water/dust, dew, freezing/thawing, cold, heat, UV radiation, traffic vibration, biological treatment, ozone, water, and water spray (wet/dry). Special attention is paid to the combination of different materials within a device or in combination with other devices (e.g., the combination of different acoustic elements or the combination of acoustic and structural elements).

Roadside noise reduction devices must not only meet their acoustic functions and structural design requirements in accordance with relevant documentation, but also maintain their performance throughout their required operational life. Structural elements must maintain minimum acceptable safety factors at the end of their operational life, and acoustic elements must not only remain structurally effective but also provide the specified acoustic performance. All elements within the structure of noise reduction devices must be resistant to electrolytic or chemical corrosion and embrittlement, dimensionally stable, and generally possess a high degree of aging resistance under a wide range of conditions.

The structural design must comply with the requirements of relevant legal regulations. The standard environmental categories selected for road traffic noise reduction devices, along with their possible variations, are provided in the annex to this standard (Annex A). The manufacturer must list the measures taken to limit the effects of aging on the product, list the factors affecting aging, and list the adverse effects of combining different materials.

Where material standards are available, durability should be assessed using these. The manufacturer should define the operating life of the noise-reducing device under the exposure classes listed in the table, adapted to its intended use. In all cases, the operating life of the noise-reducing device is the minimum operating life of its components. The adverse effects on long-term performance of ground contact should be considered. If water retention is likely to reduce operating life, the design should ensure that water is not retained. Structural and acoustic elements may have different operating lives, so they should be assessed under the same exposure conditions when installed on the same site. If changes in humidity, temperature, or UV affect the dimensional stability of the materials used in the structure, the design should allow for such changes and ensure that performance continues to meet performance specifications. When different materials are used in the structure, all appropriate precautions should be taken to prevent electrolytic and chemical corrosion or interaction that could adversely affect operating life.

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