Harmful Effect Vibration To Human
Harmful Effect Vibration To Human
Harmful Effect Vibration To Human
Publicat de
Universitatea Tehnică „Gheorghe Asachi” din Iaşi
Volumul 63 (67), Numărul 3, 2017
Secţia
CONSTRUCŢII. ARHITECTURĂ
Abstract. This paper presents the harmful effect of vibrations on the human
body. The vibration effect is quantified using the perception coefficient, K. In
order to determine the perception coefficient, measurements were made in an
area near the railways. Based on the measurements, the intensity of vibration and
the degree of human vibration perception were determined. The results show that
the vibrations generated by the railway transport and transmitted to the adjacent
areas are highly perceptible, thus imposing vibration mitigation measures.
Keywords: coefficient of perception; intensity of vibration.
1. Introduction
The two harmful factors commonly occurring in traffic are noise and
vibration. Vibrations have complex harmful effects on humans and the built
environment, affecting the health of the human body, the quality of human
work, the physical and mental comfort, the resistance of the building
components, etc.
Both mechanical and acoustic vibrations can become dangerous for
humans beyond certain limits. Studies on the harmful action of vibrations on the
human body show that vibrations produce a number of harmful effects, both
physiological and physical. For example, long-term exposure to low-frequency
vibrations ranging from 5 to 15 Hz can lead to relative displacements of various
organs, pulmonary hemorrhage, etc. (Ene, 2012).
Studies that investigate human comfort show that traffic vibrations
generate discomfort, the annoyance increases with increased vibration, and
these increase the disturbing effect of noise (Findeis, 2004; Gidlof-Gunnarsson,
2012). In addition, vibrations and noise are related to sleep disorders reported
by people exposed to rail traffic (Howarth, 1991) and lead to changes in heart
rate (Croy, 2013).
Vibrations can be transmitted to humans in three ways (Buzdugan,
1980):
a) on the whole body, through its entire surface, when it is under the
effect of sound waves in the air, or immersed in water;
b) on the whole body, through the surface of contact with the
environment, when the person is standing, sitting or lying down;
c) on parts of the body, for example hands that perform certain
technological operations.
For the human body, the direction of the vibratory motion is also of
interest (Buzdugan, 1982). Thus, if we would consider three rectangular axes to
pass through the heart, the vibrations would be:
i) longitudinal, from head to toe;
ii) horizontal, perpendicular to the chest;
iii) horizontal, left-right.
It is customary to establish certain limits of vibration, depending on
their physiological level. According to ISO 2631-1: 2001, we can talk about 3
criteria for assessing the harmful effect of vibrations on humans:
1. decrease in work efficiency (fatigue limit);
2. the health hazard (threshold of harm);
3. comfort limit (threshold of perception).
3. Case Study
3.1. On-Site Measurements Description
Table 2
Types of Passing Trains During the Tests
Nr. Description
Test 1 Blank acquisition
Test 2 Train-blue arrow
Test 3 Tram
Test 4 Locomotive
Test 5 Locomotive + 1 wagon
Test 6 Locomotive + 2 wagons
Test 7 Locomotive + 3 wagons
Test 8 Locomotive + 4 wagons
Test 9 Locomotive + 2 wagons
Test 10 Locomotive + 6 wagons
At the school level, in the vertical direction, for test 2 (blue-arrow) there
is a reduction in the perception coefficient between 79% to 94%, having values
above 2 (strongly perceptible) for the frequency ranges 0,...,15 Hz and
25,...,40 Hz, and above 4 (very strong perceptible) for the 15,...,25 Hz range.
For test 7, this reduction is between 55% and 77%, with values above 2
(strongly perceptible) for the 0,...,15 Hz and 15,...,25 Hz frequency ranges, and
1.5 (well perceptible) for the 25,...,40 Hz range. For test 8, the reduction in the
perceiption coefficient is between 57% and 90%, having values above 3
(strongly perceptible) for the frequency range 25,...,40 Hz, over 4 (very strong
perceptible) for the range of 0,...,15 Hz , and over 10 for the 15,...,25 Hz range.
3. Conclusions
Although there was no freight train within the time interval in which the
measurements were taken, the frequency range for the vibrations produced by
the passenger trains ranged between 10 and 40 Hz.
As can be noted from the graphs presented, the perception coefficients
in the horizontal direction decrease at the sidewalk as a result of the amplitude
damping due to the road infrastructure, only to increase in the area of the
school.
Both in the horizontal and vertical directions, the value of perception
coefficient near the school is the most reduced one, over all frequency ranges,
yet having values that show that vibrations are strongly perceptible. For the 0-
15 Hz frequency range, those vibrations that we are most sensitive to and which
have a strong negative influence on comfort, the perception coefficient
decreases on average by 65% in the vertical direction and by 56% in the
horizontal direction. However, the K value is between 2 and 4, which means
that vibrations are strongly perceptible.
Under these circumstances, and taking into account that there are also
residential buildings in the railway area, a series of measures must be taken to
isolate the traffic area through various procedures. These could be: the
modernization of the components of the rail transport system, a vertical
systematization of the area adjacent to the railways, which could help in the
reduction of vibration transmission, the use of anti-vibration isolators.
The aim is to reduce the degree of the vibration perception in the
adjacent urban area and to increase the degree of comfort.
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*
* * Evaluarea expunerii umane la vibraţiile globale ale corpului. Partea 1. Condiţii
generale, ISO 2631-1:2001, 2001.
(Rezumat)