Sound Emission of Rail Vehicles According to ISO 3095

Noise emissions from rail vehicles are a key aspect in increasing the acceptance of rail transportation. Noise affects both the environment and the quality of life of local residents. ISO 3095 is the international standard that regulates the measurement and evaluation of noise emissions from rail vehicles.

Vorbeifahrtmessung zur Bestimmung der Geräuschemission

Overview of ISO 3095

ISO 3095 specifies the procedures for measuring the noise generated by rail vehicles. The aim is to collect consistent and comparable data in order to assess noise exposure and, if necessary, take measures to reduce noise. The standard applies to all types of railroad vehicles, including high-speed trains, freight trains and streetcars.

There are three different types of measurement:

1. Measurement at standstill:

The noise emitted by a train when standing still depends on the operating conditions. Freight wagons are only measured when at a standstill if auxiliary equipment such as engines, generators or cooling systems are present, for example in the case of refrigerated wagons.

2. Measurement when the train starts up

In type testing, a distinction is made between two cases of train start-up noise, between the maximum level and the average level

    • LpAFmax - Maximum sound pressure level
    • LpAeq,T - Sound pressure level
Position of the first measuring microphone
Train length max. 50 m Mic_1: 10 m in front of the unit
Position of the second measuring microphone
Train length up to 100 m Mic_2: 10 m in front of the center of the system
Position of the second and third measuring microphone
Train length up to 150 m Mic_2: 10 m before the halfway point of the unitMic_3: 10 m in front of the center of the unit

3. Messung bei konstanter Geschwindigkeit:

  1. Bei dieser Messung wird die Zugeinheit bei einer konstanten Vorbeifahrgeschwindigkeit gemessen. Bei der Typenprüfung wird zwischen zwei Fällen unterschieden:
    • Zugeinheiten mit einer maximalen Geschwindigkeit (v_max) > 80 km/h, die Messungen erfolgen bei v_max.

Zugeinheiten mit einer maximalen Geschwindigkeit (v_max) ≤ 80 km/h, hier erfolgen Messungen bei v_max sowie zusätzlichen Geschwindigkeiten, beispielsweise in einem Bereich von 20 km/h bis 350 km/h.

Mikrofonpositionen:

Positioning of the measurement microphones in distance and height

Measuring times:

    • Start: The front of the train triggers the measurement with a light barrier.
    • Pre-start: Observe the area before the trigger and cut out the time during which the SPL was at least 10 dB lower than at the start of the trigger.
    • Stop: If the SPL is 10 dB lower than the SPL at the time of triggering.

Measured variables:

  • A-weighted equivalent continuous sound pressure level (Mic_xxx_LAeq)
  • A-weighted equivalent continuous sound pressure level (Mic_xxx_L_Thirds_Aeq) Frequency bands: 31.5 Hz to 20 kHz (8 kHz)

For all measurements, the acoustic ambient conditions must be designed in such a way that the sound field can propagate freely. The meteorological conditions such as wind speed and direction, temperature, humidity and air pressure must be documented. Any precipitation must be noted.

As the measurements take place directly on the tracks, the external noise level must be measured and it must be ensured that other noise sources have no significant influence on the measurements. The maximum value of the extraneous noise (LpAeq,T with T = 20 s) must be at least 10 dB below the total noise at each microphone position for all microphone positions.

Requirements of ISO 3095

ISO 3095 sets out various requirements for carrying out sound measurements:

  1. Device requirements
    Calibration:     Measuring devices must be calibrated before and after measurements to ensure accurate and reliable data.
    Frequency range: The devices should be able to detect the relevant frequency range, typically from 20 Hz to 20 kHz.
  2. Measurement protocol
    Data recording:     All relevant data, including weather conditions, train speed and exact position of the microphones, must be documented.​​​​​​​
    Data analysis: The recorded sound levels must be analyzed and evaluated in relation to the corresponding guide values and limit values.
Anzeige einer Messfahrt mit Position der Messmikrofone und Ergebnisse der Spektralanalyse

Conclusion

With the help of imvc WAVE you can create an experiment that complies with ISO 3095. This standard is an essential instrument for the noise measurement and evaluation of track-bound vehicles. By complying with this standard, manufacturers, operators and authorities can ensure that noise emissions remain within acceptable limits and thus contribute to reducing noise pollution in the surrounding area.

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Noise Measurement of Rail-Bound Vehicles - Ermitted and Inside Noise

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