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PD CEN TS 16272 โ Railway Track Noise Barriers Acoustic Performance Test Methods (Part 5 In Situ Sound Reflection; Part 7 In Situ Insertion Loss)
Railway Applications โ Track โ Noise Barriers and Related Devices acting on Airborne Sound Propagation โ Test Method for Determining Acoustic Performance
๐ PD CEN/TS 16272 is a series of Published Documents issued by the British Standards Institution (BSI) based on the European Technical Specification CEN/TS 16272 for railway applications โ track โ noise barriers and related devices acting on airborne sound propagation. The series specifies unified test methods for assessing the acoustic performance of such noise insulation facilities. The two parts in this batch, PD CEN/TS 16272-5:2014 and PD CEN/TS 16272-7:2015, give in situ test procedures for the barriers’ intrinsic characteristics (in situ sound reflection) and extrinsic characteristics (in situ insertion loss) respectively โ an important basis for design selection, project acceptance and evaluation of rail noise-reduction effectiveness.
๐ก The noise-reduction effect of a barrier depends on many factors: its height, length, the sound absorption/insulation properties of the material, and its geometric position relative to the track and the receiver. “Intrinsic characteristics” describe the acoustic indices of the barrier material and components themselves, while “extrinsic characteristics” describe the actual noise-reduction performance after installation at a specific site โ both must be evaluated together.
1. Overview of the Series ๐
The CEN/TS 16272 series is prepared by the European Committee for Standardization (CEN) technical committee for railway applications โ track; the UK participates through Technical Committee RAE/2 and publishes it as a Published Document. Different parts of the series provide the different test methods needed to determine acoustic performance. The two parts in this batch are summarised below:
| Standard | Characteristic Type | Measured Parameter | Year |
|---|---|---|---|
| PD CEN/TS 16272-5:2014 | Intrinsic characteristics | In situ values of sound reflection under direct sound field conditions | 2014 |
| PD CEN/TS 16272-7:2015 | Extrinsic characteristics | In situ values of insertion loss | 2015 |
โ ๏ธ The standard distinguishes “normative” from “informative” content: normative clauses convey criteria that must be fulfilled to claim compliance, from which no deviation is permitted; informative clauses merely aid understanding or use and are not mandatory. Distinguish them carefully when referencing.
2. Part 5: Intrinsic Characteristics โ In Situ Sound Reflection ๐ช
PD CEN/TS 16272-5:2014 specifies the method for determining the in situ value of sound reflection of a noise barrier under direct sound field conditions. The sound reflection value characterises the degree to which the barrier surface reflects incident sound energy: higher reflection is more favourable for noise reduction on the protected side, but may cause multiple reflections between the barrier and the track, affecting train-noise propagation and the sound field of the surrounding environment.
The test method typically uses a sound source that emits sound towards the barrier surface, measures the reflected sound at located microphone positions, and combines this with a direct-sound reference measurement to derive the barrier surface’s sound reflection coefficient. The method focuses on the actual reflection performance of the barrier in its installed, operating environment, complementing the reflection coefficient measured in the laboratory.
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The sound reflection value gives direct guidance on material selection: the side facing the source should preferably use an absorptive-type barrier to suppress secondary reflections, while the reflection characteristics of the barrier top and the side facing away from the source influence the far-field noise reduction and the acoustic environment of the landscape.
3. Part 7: Extrinsic Characteristics โ In Situ Insertion Loss ๐
PD CEN/TS 16272-7:2015 specifies the method for determining the in situ insertion loss of a noise barrier. Insertion loss is defined as the difference in received sound pressure level at a receiver point before and after the barrier is installed (or an equivalent quantity); it is the core index that directly reflects the barrier’s noise-reduction performance under actual operating conditions.
Part 7 specifies the measurement layout, source conditions, microphone positions, use of train or artificial sources, test duration, and meteorological and ground conditions, and requires appropriate corrections so that results from different positions and different days remain comparable. The part also provides agreed speed-unit conversions (e.g., km/h to mph) for UK users.
โ ๏ธ Insertion loss is an integrated on-site result, strongly influenced by barrier geometry, distance to the track, receiver height, road and ground reflections, and meteorological conditions (wind speed, temperature gradient). For acceptance and comparison, measurement conditions must be fixed and all influencing parameters recorded, to avoid misreading the values.
4. Key Technical Requirements ๐ง
Combining the two parts, the key requirements for in situ acoustic determination include:
- Source conditions: use actual train noise or a compliant source (e.g., loudspeaker/reference source), ensuring reproducibility of source position and spectrum;
- Measurement layout: microphone positions, heights and distances to the barrier/track must comply with the standard, with coordinates recorded;
- On-site corrections: measure and correct for meteorological conditions (pressure, temperature, wind), ground reflection and background noise;
- Data statistics: take representative values from repeated measurements, presenting results by octave band or frequency weighting;
- Reporting requirements: reports must state barrier structure, measurement configuration, source type, temporal parameters and correction methods to keep results traceable.
5. Engineering Practice and Applications ๐ ๏ธ
In railway noise-environment management projects, this series is mainly used for:
- Barrier selection: compare the intrinsic characteristics of different absorptive/insulative materials and select barrier types that meet requirements;
- Design verification: input measured insertion loss into barrier design and noise-prediction models to verify predicted results at receiver points along the line;
- Project acceptance: measure insertion loss and sound reflection on site after installation to verify the design noise-reduction target is achieved;
- Performance evaluation and maintenance: periodically monitor performance degradation (e.g., material ageing, damage) to support repair and replacement decisions.
๐ก Recommendation: compare on-site measured insertion loss with simulation predictions to form a “predict โ measure โ correct” loop; at the same time record the full measurement configuration in as-built documents for future re-testing and traceability.
6. Frequently Asked Questions โ
โ Q: What is the difference between intrinsic and extrinsic characteristics?
A: Intrinsic characteristics (e.g., sound reflection) depend on the barrier’s own material and component properties; extrinsic characteristics (e.g., insertion loss) are the combined result of the barrier installed at a specific site, involving geometry, ground and source conditions. They evaluate barrier acoustic performance at different levels.
A: Intrinsic characteristics (e.g., sound reflection) depend on the barrier’s own material and component properties; extrinsic characteristics (e.g., insertion loss) are the combined result of the barrier installed at a specific site, involving geometry, ground and source conditions. They evaluate barrier acoustic performance at different levels.
โ Q: Why measure sound reflection under “direct sound field conditions”?
A: Direct sound field conditions simplify the incidence relationship of sound waves, making it easier to separate and measure the reflected sound with a prescribed method and to ensure repeatability and comparability; this is a common controlled measurement condition in test-method standards.
A: Direct sound field conditions simplify the incidence relationship of sound waves, making it easier to separate and measure the reflected sound with a prescribed method and to ensure repeatability and comparability; this is a common controlled measurement condition in test-method standards.
โ Q: Can insertion loss be directly equated to the barrier’s “sound insulation”?
A: No. Sound insulation (transmission loss) is an intrinsic property of a material/component determined in the laboratory; insertion loss is the integrated on-site noise-reduction effect, including barrier height, length, diffraction, ground and meteorological influences.
A: No. Sound insulation (transmission loss) is an intrinsic property of a material/component determined in the laboratory; insertion loss is the integrated on-site noise-reduction effect, including barrier height, length, diffraction, ground and meteorological influences.
โ Q: Why does the standard provide km/h to mph conversion values?
A: European standards use metric speeds while the UK uses imperial units. To ease UK application, the standard lists agreed conversion values (e.g., 5 km/h โ 3 mph, 200 km/h โ 125 mph) and advises against using exact converted “absolute” values to avoid ambiguity.
A: European standards use metric speeds while the UK uses imperial units. To ease UK application, the standard lists agreed conversion values (e.g., 5 km/h โ 3 mph, 200 km/h โ 125 mph) and advises against using exact converted “absolute” values to avoid ambiguity.
โ Q: Is on-site measurement strongly affected by weather?
A: Very much. Wind speed, temperature gradients, pressure and precipitation all change sound propagation paths and results. The standard requires meteorological effects to be recorded and corrected, and, where necessary, measurement to be suspended or prolonged under adverse weather.
A: Very much. Wind speed, temperature gradients, pressure and precipitation all change sound propagation paths and results. The standard requires meteorological effects to be recorded and corrected, and, where necessary, measurement to be suspended or prolonged under adverse weather.