Noise arises from many different types of sources and activities. The simple definition of noise is that it is unwanted sound, and as such, may have both direct physical and psychological effects on people if it is intense or persistent enough; causing sleep disturbance, interfering with normal conversations, or annoyance and stress. The running noise generated by the high-speed rail may be highly annoying due to prolonged exposure to nearby residences and living environment, so it should be within the regulated limit. Evidence is accumulating that noise has real health effects on people.

This paper on noise is based on CPCB (Central pollution Control Board) guidelines in India and other international standards/regulations. The scope of this paper includes an assessment of standards, regulations, and recommended practices with a focus on high-speed rail.
 

1. Noise standards and regulations worldwide:

1. 1.1

   CPCB (Central Pollution Control Board) noise guidelines in India [1]:

Mathematically equivalent noise level is expressed as below –

Where,

Leq(t)=equivalent sound level of time period “t”, dBA

T= time period, sec (3600 for an hourly Leq(1hr))

N=number of samples, sec (3600 for an hourly Leq(1hr))

i=index of summation

Li = individual A-weighted sound level, dBA

Table 1 shows the CPCB equivalent noise limits for day and night in India.

Table 1: Ambient Air Quality Standards in respect of Noise [1]

Note:
1. Day time shall mean from 6 a.m.-10 p.m.
2. Night time shall mean from 10 p.m. - 6 a.m.
3. Silence zone is an area comprising not less than 100 meters around hospitals, educational institutions, courts, religious places or any other area which is declared as such by the competent authority
4. Mixed categories of areas may be declared as one of the four above mentioned categories by the competent authority

*dB(A) Leq denotes the time weighted average of the level of sound in decibels on scale A which is relatable to human hearing.

A “decibel” is a unit in which noise is measured.

“A”, in dB(A) Leq, denotes the frequency weighting in the measurement of noise and corresponds to frequency response characteristics of the human ear.

Leq: It is an energy mean of the noise level over a specified period.

Relaxation: Complaints to be made to the authority:
A person may, if the noise level exceeds the ambient noise standards by 10dB(A) or more given in the corresponding columns against any area/zone or, if there is a violation of any provision of these rules regarding restrictions imposed during night time, make a compliant to the authority.

1. 1.2 Environmental Quality Standards for Shinkansen Super Express Railway Noise in Japan [2]:

In Japan, LpASmax,  the maximum A-weighted sound pressure level i.e. Peak noise is used for noise standards as shown in Fig-(1).

The values of the environmental quality standards are established for each category of area shown in Table 2.

Table 2- Noise guidelines in Japan

Note: Area category I refer to areas used mainly for residential purpose and area category II refers to other areas, including commercial and industrial areas, where the normal living conditions shall be preserved.

Measurement and evaluation method:

• Measurements shall be carried out by recording the peak noise level of each of the Shinkansen trains passing in both directions, in principle, for 20 successive trains
• Measurements shall be carried out outdoors and in principle at the height of 1.2meters above the ground and at a distance of 25 m from the centre of track. Measurement points shall be selected to represent the Shinkansen railway noise levels in the area concerned, as well as points where the noise is posing a problem.
• Any period when there are special weather conditions or when the speed of the trains is considered lower than normal shall be avoided when selecting the measurement time.
• The Shinkansen railway noise shall be evaluated by the energy mean value of the higher half of the measured peak noise levels.
• The measuring instrument used shall be with A-weighted calibration and slow dynamic response.

The environmental quality standards provided shall apply to Shinkansen railway noise from 6 a.m. to 12 midnight.

1. 1.3 EU Commission Regulation- TSI ‘Rolling stock-noise’ [3]-

Limits for pass-by noise/ Normalizing passby Noise for Vmax > 250km/h:

The Pass-by Level (LpAeq,Tp) is the average of noise energy a train generates from all cars during the time of the pass-by of the entire train as shown in Fig-(2). It is defined by the following equation –

L pAeq,Tp =10 log 10 1/ T p T1T2 p A2 t dt p 02

Where, LpAeq,Tp: A-weighted equivalent continuous sound pressure level on the pass-by time (dB)

Tp : Passing time from T1 to T2 (sec)

T1 : Passing time of the front of the train (Sec)

T2 : Passing time of the end of the train (Sec)

PA(t): A-weighted instantaneous sound pressure level (Pa)

P0: Standard value of A-weighted sound pressure level (20µPa)

The limit values for the A-weighted equivalent continuous sound pressure level at a speed of 80 km/h (LpAeq,Tp(80 km/h)) and, if applicable, at 250km/h (LpAeq,Tp(250 km/h)) concerning the pass-by noise allocated to EMUs are set out in Table 3. The limit values are defined at a distance of 7.5m from the centre of the track and 1.2m above top of rail.

Measurement at speeds higher than or equal to 250km/h shall also be made at the ‘additional measurement position’ with a height of 3.5m above top of rail and 25m from the center of the track and assessed against the applicable limit values of Table 3.

Table 3: Limit values for pass-by noise [3]

 For EMUs, following classes of maximum operational speed are distinguished:

• If the maximum operational speed Vmax of the unit is equal to or higher than 250 km/h, the pass-by noise shall be measured at 80 km/h and at its maximum speed with an upper test speed limit of 320km/h. The measured pass-by noise value LPAeq,Tp(Vtest) at 80 km/h shall not exceed the limit value LPAeq,Tp(80km/h) as set out in table 3. The measured pass-by noise value at maximum speed LPAeq,Tp (Vtest) shall be normalised to the reference speed of 250 km/h LPAeq,Tp(250km/h) using Eqn. (3). The normalised value shall not exceed the limit value LPAeq,Tp(250km/h) as set out in table 3.

LPAeq,Tp (250km/h)=LPAeq,Tp(Vtest)–50*log(Vtest/250km/h) ……….(3)

    Vtest= Actual speed during the measurement

1. 1.4 UIC 660: Measures to ensure the technical compatibility of high-speed trains [4]:

The maximum values permitted in terms of equivalent noise level emission when a high speed train passes (LPAeq,Tp) are measured at a distance of 25m from the centre of the track and 3.5m above the rail level, is as follows

LPAeq,Tp max = 91 dB(A) at 300 km/h

The measurements shall be made on a sample of several trainsets representative of the population concerned. The value to compare with the limit value LAeq,tp max is the mean of the values LAeq,tp measured for each trainset.

It is noted that direct comparisons of regulated noise limits worldwide are difficult due to the variations in metrics (Such as LpAeq,Tp (Pass by noise) and LpASmax (peak noise)), measurement locations, and measurement procedures. 

CPCB (Central Pollution Control Board) under Ministry of Environment & Forests framed the noise pollution (Regulation and control) rules, 2000 in India, specifying ambient air quality in respect of all noise events in the atmosphere and not the Railway noise. Hence, it is pertinent to develop guidelines on Pass-by noise limits from a single source i.e. Railway noise etc. measuring at certain distance like in Japan (MLIT guidelines) and Europe (UIC 660), in India also. 

The IRS (International Railway Standards) High-Speed Working Group of UIC including European, Japanese, Chinese and Indian High-Speed rail operators are meeting regularly to produce new IRSs or update/migrate UIC leaflets to become IRS that will be accepted globally. Preparation of IRS 60660: Compatibility of high-speed trains that is the new version of UIC 660 has started in 2021. At present, in IRS 60660 noise clause has been framed as “The limit value of LpAeq,T (pass by noise) shall be defined in accordance with the legislation of each country”. Since Indian High Speed Railway Noise limits are yet to be developed, it is recommended to adopt popular standard among presently-available high speed trainsets from key manufacturers i.e. UIC 660: Measurements to ensure the technical compatibility of high-speed trains in India.

1. The Noise Pollution (Regulation and Control) Rules, 2000 – CPCB rules in India

2. Environmental Quality Standards for Shinkansen Super express Railway Noise in Japan

3. Commission Regulation (EU) No 1304/2014 of 26th Nov’14 on the technical specification for interoperability relating to the subsystem ‘rolling stock- noise’ amending Decision 2008/232/EC and repealing Decision 20111/229/EU

    

4. UIC 660 – Measures to ensure the technical compatibility of high-speed trains