Maritime University of Szczecin
Akademia Morska w Szczecinie
2011, 27(99) z. 1 pp. 59–65 2011, 27(99) z. 1 s. 59–65
The protection of environment and employees against
the noise emitted during the groundwork
Ochrona środowiska i pracowników przed hałasem
powstającym w czasie prac ziemnych
Marianna Kazimierska-Grębosz
Technical University of Łódź, Faculty of Organization and Management Politechnika Łódzka, Wydział Organizacji i Zarządzania
90-924 Łódź, ul. Piotrkowska 266, e-mail: dankazim@p.lodz.pl
Key words: acoustic screens and curtains, equivalent sound level, environment of work, small earthmoving
machines, directives of European Union
Abstract
The paper presents the problem of high level of noise at workplace of operators of earthmoving machines and the problem of noise emitted by these machines to the environment. The paper presents also the basic information concerning the administrative methods of noise control like EU directives and regulations of the Polish authorities concerning noise level at workplace and the noise emitted to the environment.This paper shows the results of experiments on use of acoustic screens to lower the noise levels emitted during small earth moving machines operations. A significant damage of acoustic climate during road works was proven.
Słowa kluczowe: ekrany i kotary akustyczne, równoważny poziom dźwięku, środowisko pracy, małe
maszyny do prac ziemnych, dyrektywy Unii Europejskiej
Abstrakt
W pracy przedstawiono problem wysokiego poziomu hałasu na stanowiskach pracy operatorów maszyn do prac ziemnych oraz problem hałasu emitowanego przez te maszyny do otaczającego środowiska. Przedstawiono podstawowe informacje o administracyjnych metodach zwalczania hałasu: dyrektywy Unii Europejskiej i rozporządzenia polskich władz, dotyczące poziomu hałasu na stanowiskach pracy oraz hałasu emitowanego do środowiska. Wykazano naruszenie klimatu akustycznego w czasie prac remontowych ulic. W artykule przedstawiono wyniki badań nad zastosowaniem ekranów akustycznych w celu obniżenia poziomu hałasu emitowanego w czasie pracy małych maszyn roboczych do prac ziemnych.
Introduction
Noise in the city environment caused by the intensive road movement often exceeds values permitted by standards. Often even the critical noise level – called threshold level – is exceeded, which value is equal to 75 dB during the day for living build-up. High level of noise present in the streets of cities grows during road works of these streets. Most road works are conducted for several hours or even days. As shown in the paper, on influence of road works on the noise levels in cities [1] the degree of acoustic climate damage during road works encounters a 15% to 20% growth. Road
noise, street noise is evaluated by people as the most onerous, and this onerousness grows during road works on pavements and streets without stopping or limiting of movement. In such cases not only the noise levels but also the dust concentration in air around the machines grows. The negative effects of this type of road works could have been seen by inhabitants of Łódź during the execution of Łódź Regional Tramway project. The works in separate sections took up to several months.
The negative impact of high level of noise emitted by machines during reparations affects not only the environment, but also the operators of
machines. Pollination is the second (after the noise) negative factor which affects the workers.
The aim of this paper is to present the results of researches of the equivalent sound level emitted by the small earthmoving machines and their compa-rison to the existing directives and standards. The researches were carried out in 2009–2011 in the real conditions with use of small earthmoving machines. In the paper, the methods of reduction of the harmful effects of noise on the environment are also proposed.
The administrative methods of noise reduction
The methods of noise reduction are divided into technical and administrative methods. The adminis-trative methods are primarily the legal acts estab-lished and introduced by:
the state administration, the local authorities,
other offices establishing regulations and proce-dures, for example in the factories.
The official prohibitions, ordinances and regu-lations are intended to reduce environmental noise and to protect employees in the workplace.
These methods are designed to:
ensuring the right conditions of rest for people, ensuring an correct level of sound in the
work-place and at home,
reduce the noise emitted by communication and by industry in those areas where the noise should be minimal.
Directives and standards concerning protection against noise
The most important European Union directives and regulations of the Polish government con-cerning the protection against noise are:
Directive 2000/14/EC of the European Parlia-ment and of the Council of 8th May 2000 on the
approximation of the laws of the Member States relating to the noise emission in the environment by equipment for use outdoors. The decisions from this directive were introduced to the national law by the decree of Minister of Eco-nomy of 21st December 2005 (Dz.U. no. 263,
item 2202);
Directive 2005/88/EC of the European Parlia-ment and of the Council of 14th December 2005
amending Directive 2000/14/EC on the approxi-mation of the laws of the Member States relating
equipment for use outdoors. The decisions from this directive were introduced to the national law by the decree of Minister of Economy of 15th February 2006 (Dz.U. no. 32, item 223) and by the decree of Minister of Economy of 28th May
2007 (Dz.U. no. 105, item 718);
Directive 2003/10/EC of the European Parlia-ment and of the Council of 6th February 2003 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (noise) – (Seven-teenth individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC). The decisions from this directive were introduced to the national law by the decree of Minister of Economy and Labour of 5th August 2005 (Dz.U.
no. 157, item 1318);
Directive 2002/44/EC of the European Parlia-ment and of the Council of 25th June 2002 on the
minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (vibration) (six-teenth individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC). The Directive 2002/44/WE was changes by Directive 2007/30/WE and decree of EU number 1137/2008.
The most important international ISO standards concerning the protection against noise are:
• ISO 1999:1990 : Acoustics – Determination of occupational noise exposure and estimation of noise-induced hearing impairment;
• ISO 9612:2009: Acoustics – Determination of occupational noise exposure – Engineering method;
• ISO 9612:1997 : Acoustics – Guidelines for the measurement and assessment of exposure to noise in a working environment;
• ISO 10843:1997 : Acoustics – Methods for the description and physical measurement of single impulses or series of impulses.
The most important guidelines in the directives and decrees
Concerning the environment of work:
The decree of the Minister of Economy and Labour of 5th August 2005 introduced a new term
concerning noise: “exposure action values” [2]: • For daily noise exposure level which is the
timeweighted average of the noise exposure levels for a nominal eight-hour working day – exposure limit value is fixed at 80 dB;
levels for a nominal eight-hour working day – NDN is fixed at 85 dB;
• Maximal sound level A can not exceed 115 dB. Concerning the urban environment: (Tab. 1). Concerning the machines and equipment to use outdoors [3]:
In the annex for the decree of 2006, the limits of the guaranteed sound power level for selected equipments were presented. Equipment shall not be placed on the market or put into service until the manufacturer, or his authorised representative established in the Community, ensures that: the equipment satisfies the requirements concerning the noise emission in the environment of the Directive, the conformity assessment procedures of this Directive have been completed, the equipment bears CE marking and the indication of the guaranteed sound power level and is accompanied by an EC declaration of conformity. Machines and equipment should have CE mark and the indication of the guaranteed sound power level.
The researches of small earthmoving machines
Measurement conditions
Experimental acoustic examinations of work machines were made on machines currently operating in the streets during road works. The earth moving machines were examined. Measure-ments of noise level emitted during machines operation were made according to the guidelines from PN-N-01341, PN-ISO 1996-1, PN-N-01307 [4]. Equivalent sound level A, LAeq,T was measured:
T A T Aeq p t t p T L 0 2 0 , d 1 lg 10 (1) in which:T – exposition time in seconds during a
work-ing day,
pA(t) – instantaneous acoustic pressure value,
corrected according to the character of A. The measurements of equivalent A noise level (Leq) were made using a precise integrating sound
detector type 2238A by the Brüel & Kjær Company with an octave filter. The program Noise Explorer Type 7815 was used during the realisation of researches.
The measurements were made in eight measuring points, 2 m and 1 m away from the machine to determine the influence of the acoustic background on the noise to obtain as credible results as possible. Also, measurements in the operators’ working places were made, with measuring point located 0.1 m from the employee ear and measurements at the height of a person walking by ear height, 2 m away from the machine. For all measurements the level of background noise was measured.
Subject of researches
For the researches the following machines were selected:
• circular saw TRAg 180AR, 1400 W, 7000 obr/min., (saw A);
• circular saw PERFORMANCE POWER NT 2200 M (2200 W), (saw B);
• circular saw for wood BHS 55, (1020 W, 4000 obr/min.), (saw C);
• rotary hammer BOSCH, 1350 W, GBH7-46DE; • compactor WACKER 2 KW – vertical;
• compactor Honda 4 KW – horizontal.
The selected machines are presented on the figure 1.
The selected machines were used from several years. All machines, except the saw C, had the CE mark and the declaration of sound power.
Table 1. Admissible noise levels in the city Tabela 1. Dopuszczalne poziomy hałasu w mieście
No. Type of area
Admissible long-term average level of sound A in [dB]
Roads and Railways other facilities and activities chich are the source of noise
LDWN
interval of reference time equal to all the days of the year
LN
interval of reference time equal to all the
nights
LDWN
interval of reference time equal to all the days of the year
LN
interval of reference time equal to all the
nights
1 2 3 4 5 6
4 a) Areas in the centers in the cities with over 100 000
of inhabitants
65 55 55 45
Taking into account the classification of noise, the noise generated by the examined machines can be classified as [5]:
• external noise; • audible noise;
• instant noise – a break in the emission are longer than 2 minutes, the machine did not work for a minimum of 5 hours, with changes in noise levels up to 5 dB;
• impact noise – the noise of the machines characterized by a rapid fluctuation of sound pressure level;
• installation noise – industrial sources. The measurement results
The results of measurements indicate a consider-able excess of admissible values. It should be noted that the value of 65 dB concerned LAeq D relates to
an equivalent noise level in the interval of the reference time equal to 16 hours of the day. The examined machine do not work in that period of time, but in case of long-term repair works, noise of operating machines can not be considered as short-term or incidentally.
The examined machines should have an indi-cation of the guaranteed sound power level. Two of the machines did not have this sign. The results of measurements indicate that the determination of sound power level does not guarantee the emission of admissible level of noise by machines that work
For all examined machines, we observe low levels of noise for the frequency 125 – 500 Hz, the highest for 4000 – 8000 Hz. These levels are, for example for: concrete saw – 125–500 Hz appro-ximately 70 dB, 4 to 8 kHz approappro-ximately 90 dB, saw for wood: 125–500 Hz approximately 65– 70 dB, 4–8 kHz approximately 95 kHz – 100 dB (Fig. 2 and 3).
Fig. 2. Comparison of equivalent noise levels measured during the machines work with the level admissible according the decree of Minister of Environment; 1 – saw A, 2 – saw B, 3 – saw C, 4 –hammer, 5 – horizontal compactor, 6 – vertical compactor
Rys. 2. Porównanie poziomów równoważnych hałasu zmierzo-nego w czasie pracy maszyn z poziomem dopuszczalnym według Rozporządzenia Ministra Środowiska; 1 – piła A, 2 – piła B, 3 – piła C, 4 – młot, 5 – zagęszczarki pozioma,
90 102 99 91 85 89 65 0 20 40 60 80 100 120 1 2 3 4 5 6 Maszyna L eq [d B ] Machine Leq [d B]
Fig. 1. Selected machines Rys. 1. Badane maszyny
The researches confirmed the excess of the values of NDN of the occupational exposure limits in workplaces of machine operators. These excess ranged from 5 dB to 20 dB.
Only 20% of machine operators used personal hearing protectors.
Research of models of acoustic screens and curtains
Subject of research
Due to extremely high levels of noise touching the users of streets during the street repair works, the researches were concentrated on protection against this noise [4]. In the next stage of the researches the measurement of noise generated
during the work of these machines with the use of models of acoustic screens and acoustic curtains were made. Six models of portable acoustic screens measuring 1.5 m 1 m, 2.5 m 1 m, 2 m 1.5 m were built. The screens were made of acoustic foil with a thickness of 2 mm and acoustic and panels PD2 with a thickness of 20 mm. Two models of acoustic curtains were butli. The size of curtains are following: curtain A – width 1.74 m, height 0.88 m, curtain B – width 2.5 m, height 0.88 m. The exam-ples of models of screens are shown in figure 4. Conditions of measurements
During the examination several hundreds of measurements for each screen type were made to
Fig. 4. Models of screens made from the panels PD2, acoustic felt and film
Rys. 4. Modele ekranów z płyt dźwiękoizolacyjnych PD2 oraz filcu akustycznego i folii
Fig. 3. Average level of noise for all points of measurement during the work of the saw for wood
Rys. 3. Uśredniony poziom hałasu, dla wszystkich punktów pomiarowych, emitowany w czasie pracy piły do drewna
50 55 60 65 70 75 80 85 90 95 100 105 110 31,5 63 125 250 500 1000 2000 4000 8000 f[Hz] L eq [d B ] Leq [d B] f [Hz]
obtain credible results. Leq measurements in the
same spots were also made, after using the acoustic screen models located 1 m away and if possible 0.5 m away from the machine. The microphone was located 0.5 m, 1 m, and 1.5 m away from the screen. Due to real, changing measurement condi-tions, the measurements in the eight points were repeated many times in different time. This allowed determining the acoustic efficiency ∆L (insertion loss, IL) of the screens. Also, the level of noise as a function of frequency was measured, using the octave filter, both during machine operations with and without the screen. The efficiency of screen models used was measured for various positions of side wings in relation to the main part of the screen. The measurement results
The researches of acoustic efficiency (IL) of six models of acoustic screens allowed to determine the average value of IL and to assess the impact of various factors on the noise levels reduction. Four models of screens – selected after the measu-rements with one machine – represented the fol-lowing average values of IL at a distance of 1 m from the screen:
model of screen II: 8–9 dB, model of screen III: 8–10 dB, model of screen V: 9–14 dB, model of screen VI: 12–18 dB.
The figures 5 and 6 show the examples of noise level reductions after the application of screen built with PD2 panels.
In case of application of acoustic curtains, the positive results were also achieved. The reduction of the noise level was 10 dB and it was therefore less than after the application of screens. The range
Fig. 6. Comparison of the levels of reductions of noise emitted by the saw for wood after the application of different screens Rys. 6. Porównanie poziomów obniżeń hałasu emitowanego przez piłę do drewna przy zastosowaniu różnych ekranów Conclusions
The measurement results shown in figures 5–6 are just a small percent of the experiments perfor-med. They are a representation of the whole work. The noise was reduced by 8 dB to 25 dB by the screens. The conclusions below were formed basing on repeated measurements in various times of the day and in various movement on the street where the measurements were taken.
Analysing all the results it was concluded, that: The best results were given by rectangular,
double-layer screens, made from soundproofing panels and styrofoam. The acoustic efficiency of them was as high as 25 dB. The used materials allow using the screens in various weather conditions. The drawback is the higher weight of such screens;
An increase of the acoustic efficiency IL of the screens with the increasing distance from the screen was satisfactory, taking into conside-ration the influence of sound coming to the
a) b)
Fig. 5. Comparison of noise level emitted by a concrete saw (a) and vertical compactor (b) without and with acoustic screen Rys. 5. Porównanie poziomu hałasu emitowanego przez piłę do betonu (a) oraz zagęszczarkę (b) z bez ekranu i z ekranem
70,0 72,0 74,0 76,0 78,0 80,0 82,0 84,0 86,0 88,0 90,0 92,0 94,0 96,0 98,0 100,0 1 2 3 4 5 6 7 8 measurements points L [d B ]
without screen with screen
80,0 82,0 84,0 86,0 88,0 90,0 92,0 94,0 96,0 98,0 100,0 102,0 104,0 106,0 108,0 110,0 1 2 3 4 5 6 7 8 measurements points L [d B ]
without screen with screen
measurements points
Leq
[d
The effective sound insulation value of the same screen is different for different machines, depends on the noise level emitted by the machines;
In case of double models of 1.5 m height one should adjust the economical analysis to determine, whether the increase of cost of construction of such screens is compliant with the increase of the acoustic efficiency of these screens.
Taking into consideration the requirements for admissible levels of noise in the environment and the working environment, the application of all types of protection should be consider. The operators of machine should use the personal protection. The users of streets can not use such protection, therefore they should be protected in other ways like by using of the portable acoustic screens and curtains.
Further works on portable acoustic screens protecting from noise, as well as other types of contamination created during the operation of the machines are conducted.
References
1. KAZIMIERSKA M.: The problem of noise emitted by small earth moving machines. 7th international Conference
“Research and Development in Mechanical Industry” RaDMI 2007 September 2007, Belgrade, Serbia.
2. Rozporządzenie Ministra Gospodarki i Pracy z dnia 5 sierpnia 2005.
3. Dyrektywa 2000/14/WE Parlamentu Europejskiego i Rady z 8 maja 2000 r. o zbliżeniu przepisów prawnych Państw Członkowskich dotyczących emisji hałasu do otoczenia przez urządzenia używane na zewnątrz pomieszczeń. 4. KUCHARSKI R.: Podstawy stosowania ekranów
akustycz-nych w środowisku. Materiały Międzynarodowej Konfe-rencji „Walka z hałasem na etapie projektowania” 2003. 5. ENGEL Z.: Ochrona środowiska przed hałasem.
Wydaw-nictwo Naukowe PAN, Warszawa 1993.
Other:
6. VAL M.: Acousitque applique. Dunod. Paris 2002.
Recenzent: dr hab. inż. Zbigniew Matuszak, prof. AM Akademia Morska w Szczecinie
