J012455865

IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE)
e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 12, Issue 4 Ver. V (Jul. - Aug. 2015), PP 58-65
www.iosrjournals.org
DOI: 10.9790/1684-12455865 www.iosrjournals.org 58 | Page
Determination of maximum noise from train horn using
additional parameters
Utkarsh Singh
Department of Civil Engineering Indian Institute of Technology, Delhi Delhi-110016
Abstract: The maximum noise produced by the train horn is calculated keeping in mind various factors like
Doppler’s effect (Christian Doppler 1842) on frequency of noise emitted and dampening of sound with distance.
The critical angle and noise are calculated using calculus and MATLAB. Suggestions regarding the shape,
orientation, placement and height of the barriers are also mad in the end keeping in mind the regulations provided.
I. Introduction
1.1 Train Horn Noise
Under the Train Horn Rule (49 CFR Part 222), locomotive engineers must begin to sound train horns
at least 15 seconds, and no more than 20 seconds, in advance of all public grade crossings. If a train is traveling
faster than 60 mph, engineers will not sound the horn until it is within ¼ mile of the crossing, even if the
advance warning is less than 15 seconds.
Train horns must be sounded in a standardized pattern of 2 long, 1 short and 1 long blasts. The pattern
must be repeated or prolonged until the lead locomotive or lead cab car occupies the grade crossing. The rule
does not stipulate the durations of long and short blasts.The maximum volume level for the train horn is 110
decibels which is a new requirement. The minimum sound level remains 96 decibels.
1.2 Train Horn Rule
In response to an increase in nightime collisions at locations with state whistle bans, Congress enacted
a law that required FRA to issue a Federal regulation requiring the sounding of locomotive horns at public
highway-rail grade crossings. It also gave FRA the ability to provide for exceptions to that requirement by
allowing communities under some circumstances to establish "quiet zones."
The Final Rule on Use of Locomotive Horns at Highway-Rail Grade Crossings, published in the Federal
Register on April 27, 2005, was intended to:
 Maintain a high level of public safety by requiring the sounding of locomotive horns at public highway-rail
grade crossings;
 Respond to the concerns of communities seeking relief from train horn noise by considering exceptions to
the above requirement and allowing communities to establish “quiet zones”; and
 Take into consideration the interests of localities with existing whistle bans.
II. Literature Review
2.1 CPCB (Central Pollution (noise) Control Board)Norms
The ambient noise standards being followed in India for different types of zones are (CPCB, 1991)
Sr. no. Area Leq dB
Day Time Night Time
1. Industrial area 75 70
2. Commercial Areas 65 55
3. Residential Area 55 45
4. Silence Zone 50 40
Table 2.1 Noise Level Standards for Residential Area in India (Arvind Kumar Shukla( 2011))
The noise levels at night are generally 10 dB lower as compared to day time because of almost 50-60%
reduction in volume of traffic going through. Hence due to noises from other sources being lower the noise
level standards are lower.
2.2 A-Weighted sound pressure level
A-weighting is the most commonly used of a family of curves defined in the International standard
IEC 61672:2003 and various national standards relating to the measurement of sound pressure level.

Determination of maximum noise from train horn using additional parameters
Fig 2.1: A-Weighted sound level(Nilsson, Mats E 2007)
2.3 Doppler Effect
The Doppler effect is observed whenever the source of waves is moving with respect to an observer.
The Doppler effect can be described as the effect produced by a moving source of waves in which there is an
apparent upward shift in frequency for observers towards whom the source is approaching and an apparent
downward shift in frequency for observers from whom the source is receding. It is important to note that the
effect does not result because of an actual change in the frequency of the source.
* source
s
v v
f f
v v
 
    
  
(1)
f  = apparent frequency
v = velocity
 = apparent wavelength
sv = speed of source
sourcef = frequency of source
2.4 Sound pressure level (SPL)
The decibel dB or dB SPL (Sound pressure level) in acoustics is used to quantify sound pressure
levels and intensities relative to a reference on a logarithmic scale. The intensity level IL of a sound intensity
I is defined by
1010log
o
I
IL
I
 
  
 
(2)
oI = Reference intensity
Since the intensity carried by a traveling wave is proportional to the square of the pressure
amplitude, the intensity level can be expressed as the sound pressure level as
2
10 102
10log 20loge e
o o
P P
SPL
P P
   
    
   
(3)
Where eP the measured effective is pressure amplitude of the sound wave and oP is the reference
effective pressure amplitude. The effective sound pressure is the root mean square of the instantaneous sound
pressure over a given interval of time.

2.5 Relationship between SPL and frequency
As it is visible from above formula there is no direct co-relation between SPL and frequency but still
for sounds near 3000 to 4000 Hertz, the ear is extra-sensitive; these sounds are perceived as being louder than a
1000 Hertz sound of the same intensity. At frequencies lower than 300 Hertz, the ear becomes less sensitive;
sounds with this frequency are perceived as being less loud than a sound of the same intensity and 1000 Hertz
frequency. The loss of sensitivity gets bigger as one goes to lower frequencies. Also, at very high frequencies
sensitivity is again reduced.
2.6 Damping
The sound intensity is related to distance by inverse square rule:
2
1
I
d
 (4)
I = Sound intensity
D= Distance
Since,
2
I kp (5)
p = pressure
So,
1
p
d
 (6)
The inverse relationship will be used in this report
2.7 Noise Meter
A sound meter is an instrument that measures sound pressure level, commonly used in noise pollution
studies for the quantification of different kinds of noise, especially for industrial, environmental and
aircraft noise.
2.8 Noise Barrier
Noise barriers are exterior structures provided to protect sensitive land uses from noise pollution. In
fact, noise barriers are the most effective tools of mitigating roadway, railway, and industrial noise sources. The
way of increasing (propagating) or decreasing (attenuating) of noise between the source and the receptor is
dependent on various factors such as location of barriers and receptors, height and materials of noise barriers
etc. Roadside noise barrier have shown to reduce the near road air pollution concentration levels. Within 15–50
m from the roadside, air pollution concentration levels at the lee side of the noise barriers can be to reduce up to
about 50% compared to open road values
2.9 Noise Barrier Efficiency
The efficiency of noise barrier should be such that the noise levels are less than the above standards.
*100
eq
IL
L
  (7)
IL = insertion loss, the loss of noise due to insertion of noise barrier
Leq = is the L at a receiver resulting from the operation of a single piece of equipment over a specified time
period
Insertion loss can be estimated by using the model proposed by Kurze and Anderson (Kurze 1971). It is the
result of compiling data of many researchers onto a single plot and developing a curve fit for a point source.
The equation is given below:
(8)
Where:
N is defined as the Fresnel number, a non-dimensional measure of how much farther the sound must travel as a
result of the barrier. It is calculated with the following equation:

l = the original length of the direct path from source to receiver
a and b = the lengths of the two straight-line segments comprising the path as modified by the noise barrier
from receiver and source
f = is the sound frequency in Hz taken to be 500 Hz for construction site
c = speed of sound in m/s taken as 324m/s
Fig 2.2 Geometry of Source, Barrier and Receiver (Arvind kumar shukla ( 2011)
III. Calculation Of Horn Noise
3.1 SPL vs. Frequency
As explained above there is no direct relation between SPL and frequency so we need to find a relation
between them. This was accomplished by getting the relation of SPL and frequency from their graph. Here the
correlation between speakers at 500hz and train horn is assumed.
Fig 3.1 : SPL vs Frequency for speakers
Fig 3.2 : SPL vs Frequency for Train horn

So relationship between them from graph is:
21.872*ln( ) 68.364SPL f  (9)
3.2 Doppler Equation
Fig 3.3: Schematic Diagram
Relative velocity between source and observer along the line at any point = sinTv 
Tv = speed of train
Doppler equation (1):
* source
s
v v
f f
v v
 
    
  
*
sin
source
T
v v
f f
v v 
 
    
  
(10)
Using the relation between SPL and frequency
21.872*ln( ) 68.364SPL f  (11)
*ln( )SPL A f B  (12)
Putting (10) in (12) we get
*ln( * )
sin
source
T
v
SPL A f B
v v 
 
  
 
(13)
*ln
sin
C
SPL A B
D E 
  
    
  
(14)
Adding the damping factor from (6)
cos
*ln
sin
C
SPL A B
d D E


  
    
  
(15)
Now ,
Values of constant,
The readings were taken at Delhi Cantt railway station and crossing for Chetak Express,
Train horn = 500 hz
Tv = 56 Km/hr=15.56m/sec
V=324m/s

Where,
A= 21.872, B=68.364, C=500*324=162000, D=324, E=15.56
Upon differentiating with respect to 
critical = 0.2947
f  = 500.124 Hz
0.01SPL dB 
103.57FINALSPL dB
3.3 Noise Barrier specifications
The value of Train horn is high for the pedestrians so,
A noise barrier needs to be constructed
SPL = 103.57dB
D=4.3m
Max Permissible= 75dB
We know that the barrier will be most efficient when we place the barrier at the centre of the train and
pedestrian,
So,
A B
Fig3.4 barrier diagram
H= height of barrier
AB=4.3m
Let AC=CB= x
IL=28.57
So from (8)
We have,
2
5 20log
tanh 2
N
IL
N


 
    
 
2
28.57 5 20log
tanh 2
N
N


 
    
 
2 N =15.85
N=25.92
AC+BC-AB=25.92
AC+BC=30.22
H
4.3m
C

Again by differentiating we get
H=14.96m
IV. Result
1. Variation of SPL with frequency is given by 21.872*ln( ) 68.364SPL f  for sound with average
reading of 104dB
2. critical for chetak express comes out to be 0.2947
3. f  for the train changed to maximum of 500.124 Hz for the observer 4.3m away from the engine
4. 0.01SPL dB  after the application of Doppler effect and damping
5. Height of noise barrier required = 2m +14.96m =16.96, so a noise barrier of 17m of steel puff panel will be
required to mitigate the noise.
6. This change will become significant as the speed of train rises and for bullet trains there is 6SPL dB 
7. The angle critical changes to 2.5
for bullet trains.
V. Conclusion
The relation between frequency and SPL is established as given above. This is supported by the
experimentally obtained values. It has also been shown that the sound level will be maximum for the
critical .Also there is definite change in the value of SPL. The change here is small but will become significant
for higher values of train speed, distance of observer and frequency of train horn. There is a definite need of
sound barrier and can be placed at a orientation as given in the figure.
Fig 6.1: Noise barriers oriented at an angle (www.noisebarriers-hosekra.com)
Acknowledgments
I would like to take this opportunity to express my deep sense of gratitude and profound feeling of
admiration to my thesis supervisor.
I would like to express my special thanks of gratitude to Prof A.K. Nema who gave me the golden
opportunity to do this wonderful project and also helped me in doing a lot of Research and I came to know
about so many new things I am really thankful to him and for his guidance.
I am highly indebted to my friends for their guidance and providing necessary information regarding
the project & also for their support in completing the project. I would also like to thank my friend Paras Garg
also pursuing research in similar area for his valuable inputs and peerless contribution to project.
Last but not the least, I would like to express my gratitude towards my parents and family for their
kind co-operation and encouragement which was a constant force of motivation in completion of this project.
I express my love and gratitude to my beloved families; for their understanding & endless love, through the
duration of the project.

References
[1]. Akhtar, Nasim, Kafeel Ahmad, and S. Gangopadhyay.2012 "Impact of environmental noise barrier in noise reduction and
frequency shift."
[2]. Daigle, Gilles A. (1998): "Technical Assessment of the effectiveness of noise walls."Noise News International 6.1 11-35.
[3]. Hanson, Carl E., David A. Towers, and Lance D. Meister (2006). Transit noise and vibration impact assessment. Chapter 6 6.-6.13
[4]. Hanson, Carl E., David A. Towers, and Lance D. Meister (2006). Transit noise and vibration impact assessment. Chapter 12 12.1-
12.8
[5]. Klingner, Richard E., Michael T. McNerney, and Ilene J. Busch-Vishniac.Design Guide for Highway Noise Barriers. Center for
Transportation Research, Bureau of Engineering Research, University of Texas at Austin, 2003. Acoustical considerations in noise-
barrier design. Chapter 2 7-12
[6]. Shukla, Arvind Kumar. (2011) "An approach for design of noise barriers on flyovers in urban areas in India." City 45: 50.
[7]. Nilsson, Mats E. "A-weighted sound pressure level as an indicator of short-term loudness or annoyance of road-traffic sound."
Journal of Sound and Vibration 302.1 (2007): 197-207.
[8]. Davis, Nancy. "Administrative Law." Det. CL Rev. (1982): 217.
[9]. Garg, Naveen, et al. "Passive noise control measures for traffic noise abatement in Delhi, India." Journal of Scientific and Industrial
Research 71 (2012).
[10]. www.noisebarriers-hosekra.com
Declaration
I do certify that this report explains the work carried out by me under the overall supervision of Dr.
A.K. Nema, Prof. Civil Engineering Department, IIT Delhi. The contents of the report including text,
figures, tables, computer programs, etc. have not been reproduced from other sources such as books, journals,
reports, manuals, websites, etc. Wherever limited reproduction from another source had been made the source
had been duly acknowledged at that point and also listed in the References.

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J012455865