- Email: [email protected]
Annual Assessment of Noise Generated by Road Traffic using Measurements
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 187 (2017) 614 – 619
10th International Scientific Conference Transbaltica 2017: Transportation Science and Technology
Annual Assessment of Noise Generated by Road Traffic Using Measurements Aleksandras Jagniatinskisa,*, Boris Fiksa, Oleksandr Zaporozhetsb, Marius Mickaitisc a
Scientific Institute of Thermal Insulation, Vilnius Gediminas Technical University, Lithuania b National Aviation University, Kyiv, Ukraine c Faculty of Civil Engineering, Vilnius Gediminas Technical University, Lithuania
Abstract The noise produced by road transport by the World Health Organization contributes basically to the environment noise pollution. The environmental noise impact by the DIRECTIVE 2002/49/EC is described using the one year average noise descriptors Lden, Lnight which usually is presented via the appropriate noise maps. However, there are cases when together with the calculation model the direct acoustic measurements are needed. The permanent noise monitoring for this purpose often is unpractical and a short-term noise level measurements become important. When long-term noise measurement (annual noise monitoring) is not applicable, the standard ISO 1996-2 allows carry out measurements in shorter time intervals than the specified one. For the case of the suburbia roads it is shown that exist the possibility to assess the one year descriptors using the data coupled from the few hours’ measurements only. As shown in paper it based on the statistics of traffic flow data for heavy and light transport (intensity, speed) as well as on the measured statistics of sound exposure levels of vehicle passing bys. For the urban traffic noise, as was shown by the statistical analysis of one year experimental data, at least one whole-day measurements are needed. In both cases chosen short-term interval or chosen whole-day must satisfy so-called representative measurement conditions. © 2017 2017The TheAuthors. Authors. Published by Elsevier © Published by Elsevier Ltd. Ltd. This is an open access article under the CC BY-NC-ND license Peer-review under responsibility of the organizing committee of the 10th International Scientific Conference Transbaltica 2017: (http://creativecommons.org/licenses/by-nc-nd/4.0/). Transportation and Technology. Peer-review underScience responsibility of the organizing committee of the 10th International Scientific Conference Transbaltica 2017 Keywords: vehicle noise, transport categories, sound exposure, representative time interval, short-term measurements
* Corresponding author. E-mail address: [email protected]
1877-7058 © 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 10th International Scientific Conference Transbaltica 2017
doi:10.1016/j.proeng.2017.04.421
615
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
1. Introduction The main descriptor that specifies the noise impact in the environmental living sites is introduced by DIRECTIVE 2002/49/EC [1] the annually averaged composite day-evening-night 24-h rating level Lden. In the recommendations provided by World Health Organization (WHO) [2] for noise impact assessment on the human health apart Lden descriptor the annual average night noise equivalent level Lnight is dealt also. In Lithuania formula for Lden determination since 2016 [3] takes a following view: ⎡1 Lden = 10 lg ⎢ 12 ⋅ 10 Ld / 10 + 3 ⋅ 10( Le +5) / 10 + 9 ⋅ 10( Ln +10) / 10 ⎢⎣ 24
(
⎤
)⎥ , ⎥⎦
(1)
where Ld is a annual average of equivalent noise level for the day 12 h period, from 07:00 to 19:00; Le is analogous descriptor for evening 3 h period, from 19:00 to 22:00 and Ln is a same descriptor for night 9 h period, from 22:00 to 07:00. Such annually averaged descriptors are very suitable for calculations and appropriately for noise maps design [4]. Using of noise maps gives a grate perspective for global estimation of environmental noise pollution to solve landscape planning tasks [5]. Noise mapping mainly based on the calculations, but may be accomplished by measurements. In used [6] and new developed [7, 8] methods the possible realizations of noise mapping calculations are described. However, there are cases when the direct acoustic measurements in some specific noise sensitive environment point are needed to confirm or not the implementation of designed measures (noise barriers construction, building façade sound insulation improvement, speed limiting, etc.) for noise abatement in these areas. The additional verifications of noise mapping results are needed for adjustment parameters for the calculation procedure also. The absence of the noise maps for interested site or e.g. the necessity to evaluate the demands for the newly designed building façade during few days duration are also require direct measurements. The situation with annual noise assessment using day-evening-night descriptor Lden is complicated due to non-stable whole-day environmental noise levels as shown in Fig. 1 and season climatic influence on the noise generated by road traffic.
Fig. 1. Typical view of whole-day time-history of environmental noise.
Some aspects of annual Lden assessment from measurements are discussed in [9−12]. In presented work two main cases of road traffic flow generated noise measurement procedures attended for the annual rating level Lden assessment are studied. The first [10] is a case when the statistic data about single vehicles passing bys are available from in-situ acoustic measurements data and the second one is an alternative case when Lden assessment may be carried out using 24-hours whole-days monitoring only [9, 11, 12]. The first case is typical for suburbia vehicle traffic flow and second one − for urban traffic flow.
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Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
2. Suburbia road traffic flow In this case exit a possibility to estimate annual Lden value by carrying out short-term measurements of traffic flow parameters in the interested living environment point nearby the suburbia road. To realise this assumption the following conditions for measurements must be fulfilled. 1. Traffic flow parameters such as an average annual speed and amount of light and heavy transport (in Lithuania two categories of road transport are taken into consideration: light and heavy) for rating time intervals 12 h day, 3 h evening and 9 h night must be available. 2. Before measurements it must be sure that weather conditions will be representative as it was stated in ISO 1996-2 [13]. At least the road surface must be dry; wind speed – less than 3 m/s and upwind of the source must be avoided. Other ground and weather conditions as ground surface type, air temperature and humidity, temperature gradients may be followed by ISO 1996-2 recommendations. 3. Measurement time period must be chosen in such manner that the remarkable part of single vehicle passing bys may be clearly identified on the time history record of sound levels as shown as examples in Fig. 2. So from enlarged 5 min. interval presented in Fig. 1b is clearly seen that practically all passing bys may be identified and their sound exposure levels (SEL) may be properly determined. The duration of measurement time must be planned so that coupled statistics of passing bys would be large enough to determine average SEL value of every vehicle category. By ISO 1996-2 the minimum registered SEL values for every transport category shall be 30 and by statistical method presented in ISO 11819-1 [14] for road surface impact assessment on traffic noise the minimum registrations shall be 100 and 80 for light and heavy transport correspondingly. It means that for measurement time optimization the density of traffic flow must be considered.
a)
b)
Fig. 2. Common view of recorded vehicle passing bys sound level time history (a) and enlarged 5 min. time history (b).
In first 1−3 items are described the preliminary conditions for measurements. Now analyze the conditions concerned measurement procedure itself. 1. Noise level generated by road transport shall be registered (measured) simultaneously using two microphones first (reference microphone) is placed near the road (10 m from the centre line of the road) on the height 4 m and second one – in the interested point of living environment site. From data coupled on reference microphone the reference SEL values may be calculated using corresponding post processing operations. Additionally from site point data, the environmental correction for noise propagation from the source (road) to the site point may be determined properly considered all environmental peculiarities. This correction is calculated as a difference between equivalent levels on the both microphones.
617
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
2. In the noise measurement interval the vehicles speed must be checked for comparison to the annual average speed of light and heavy transport. 3. Analogously synchronous video registration of vehicles passing bys must be accomplished to assign the SEL values to appropriate category of vehicle. When all of above presented conditions are fulfilled the equivalent noise levels in rating time intervals needed for Lden calculations at the reference microphone location are determined from the formula.
(
⎡τ L / 10 L / 10 + kh ⋅ 10 AE ,h LAeq,T = 10lg ⎢ ref kl ⋅ 10 AE ,l ⎢⎣ T
)⎤⎥⎥ ,
(2)
⎦
where kl, kh is an average annual amount of light and heavy transport appropriately in rating time interval T (12 h – day or 3 h – evening or 9 h – night); LAE,l, LAE,h is determined from measurements SEL average values for light and heavy transport appropriately. The difference between equivalent sound levels registered simultaneously on both microphones (reference and interested point of environment) during the measurement gives a value of real environmental correction that must be subtracted from the Lden value determined for the reference microphone position. Note that the adequacy of obtained results depends on the level of measurement data representativeness. It means that registered road traffic data as speed, vehicle categories percentage must be close to the appropriate annual values for chosen measurement time period.
3. Urban road traffic flow for conditions of Lithuania
LDEN, dBA
For the case when the single passing bys are difficult to identify and consequently SEL values are not available, the permanent monitoring during the whole-days may be used for annual Lden estimation. The principles for measurement days choosing for annual estimations may be determined from at least annual measurement data collected. Such experimental measurements are accomplished in the site point of Vilnius town placed 265 m meters from main arterial roads, where stationary urban traffic noise dominates in day 12-h time interval. The microphone was placed near façade at the 4 m height. Sound propagates from the road to the microphone as a direct line without any obstructing buildings. The influence of the season factors on Lden values for each month of the year are shown in Fig. 3 where the distribution of rating level Lden for free field conditions (façade reflection corrections of 3 dB are applied) by months is presented. 54 53 52 51 50 49 48 December
November
October
September
August
July
June
May
April
March
February
January
Fig. 3. Dependencies of free field Lden values by months with respect to the annual value of 52 dBA (dashed line).
So the monthly Lden levels clearly depend on the weather conditions, which differ with the seasons and are scattered by about 4 dBA from 49.7 dBA in January to 53.6 in October/November. The smallest noise levels in January and February are involved by low air temperature and snowy weather conditions, that follows less road
618
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
traffic and higher sound absorption by snow covering. The higher levels in the autumn months October and November may be explained by the most rainy and windy weather conditions. Annually representative results are obtained in spring and as well as in summer months’ June and August were characterized by mostly dry weather conditions. The statistical processing of one year coupled data allow to estimate the accuracy (uncertainty) of annual Lden determination using shorter time interval as one week or one day duration. Uncertainty is calculated using appropriate values of standard deviation multiplied on the coverage coefficient equal to 2 that correspond to the confidence interval with a 95 % confidence level of probability. The numerical results of annual Lden value assessment are presented in Table 1. Table 1. Estimation of yearly Lden value for chosen long-term time interval’s. Long-term reference time interval
Energy average, dBA
Standard deviation, dBA
Uncertainty interval, dBA
Month (from 12 months)
52.2
1.12
(−2.4; +2.1)
Week (representative)
52.2
0.88
(−1.8; +1.7)
Whole-day (arbitrary)
52.2
1.82
(−4.0; +3.3)
Whole-day (representative)
52.3
1.17
(−2.5; +2.2)
The uncertainty limits in calculations are not symmetrical in regard to the average values of Lden because the last ones are calculated on the energy mean principle and statistical processing may be based on the arithmetic mean only. Results presented in Table 1 shows that for traffic flow noise case acquiring sound pressure level data allows to assess the annual Lden from single representative whole-day measurements with about 2.5 dBA uncertainty. The representative conditions in this section are similar to presented in section 2.
4. Conclusions It is shown that in case when single vehicle passing bys may be identified for the most of all passing bys during the certain measurement time interval (that is typical for suburbia roads) exist a possibility to assess the annual Lden value applying short-term (till one-two hours) acoustic measurements. It based on availability of the statistics of traffic flow data for heavy and light transport (intensity, speed) as well as on the measured statistics of sound exposure levels of vehicle passing bys. The adequacy of obtained results depends on the level of representativeness of measured data. In the case when vehicle passing bys can’t be identified properly (that is typical for urban traffic) at least a one whole-day measurements are needed. The one year experimental measurement results show that annual Lden value may be assessed with about 2.5 dB expanded uncertainty using one representative whole-day acoustic measurements. One representative week (or 7 not consecutive days) measurements give 1.8 dB value of expanded uncertainty. In both cases chosen short-term interval or chosen whole-days must satisfy so-called representative measurement conditions.
References [1] Directive 2002/49/EC of the European Parliament and of the Council of 25 June 2002 relating to the assessment and management of environmental noise. [2] WHO Regional Office for Europe, 2011, Burden of disease from environmental noise, ISBN: 978 92 890 0229 5. Available from Internet: (http://www.euro.who.int/data/assets_pdf_file_0008_136466_e94888.pdf) [3] LR Triukšmo valdymo įstatymo Nr. IX-2499 pakeitimas (LR Noise regulation law amendement), TAR, 2016-05-24, Nr. 13907. [4] G. Zambon, R. Benocci, G. Brambilla, Cluster categorization of urban roads to optimize their noise monitoring, Environ Monit Asses 2016;188:26. doi: http://dx.doi.org/10.1007/s10661-015-4994-4 [5] A. Kaklauskas, E. K. Zavadskas, J. Šaparauskas, Conceptual modeling of sustainable Vilnius development, Technological and Economic Development of Economy 15(1) (2009) 154−177. [6] C. Steele, A critical review of some traffic noise prediction models. Applied Acoustics 62(3) (2001) 271–287. [7] E. A. King, H. J. Rice, The development of a practical framework for strategic noise mapping, Applied Acoustics 70(9) (2009) 1116–1127.
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
[8] J.-F. Hamet, F. Besnard, S. Doisy, J. Lelong, E. le Duc, New vehicle noise emission for French traffic noise prediction,. Applied Acoustics 71(9) (2010) 861–869. [9] E. Gaja, A. Gimenez, S. Sancho, A. Reig, Sampling techniques for the estimation of the annual equivalent noise level under urban traffic conditions, Applied Acoustics 64(1) (2003) 43−53. [10] A. Jagniatinskis, B. Fiks, M. Mickaitis, Statistical assessment of environmental noise generated by road traffic, Transport 26(1) (2011) 96– 105. [11] A. Jagniatinskis, B. Fiks,. Assessment of environmental noise from long-term window microphone measurements, Applied Acoustics 76(2) (2014) 377–385. Available from Internet: http://dx.doi.org/10.1016/j.apacoust.2013.09.007 [12] D. Geraghty, M. O’Mahony, Investigating the temporal variability of noise in an urban environment, International Journal of Sustainable Built Environment 5 (2016) 34–45. [13] ISO 1996-2:2007 Acoustics − Description, measurement and assessment of environmental noise − Part 2: Determination of environmental noise levels. [14] ISO 11819-1:1997 Acoustics − Measurement of the influence of road surfaces on traffic noise − Part 1: Statistical Pass-By methods.
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ScienceDirect Procedia Engineering 187 (2017) 614 – 619
10th International Scientific Conference Transbaltica 2017: Transportation Science and Technology
Annual Assessment of Noise Generated by Road Traffic Using Measurements Aleksandras Jagniatinskisa,*, Boris Fiksa, Oleksandr Zaporozhetsb, Marius Mickaitisc a
Scientific Institute of Thermal Insulation, Vilnius Gediminas Technical University, Lithuania b National Aviation University, Kyiv, Ukraine c Faculty of Civil Engineering, Vilnius Gediminas Technical University, Lithuania
Abstract The noise produced by road transport by the World Health Organization contributes basically to the environment noise pollution. The environmental noise impact by the DIRECTIVE 2002/49/EC is described using the one year average noise descriptors Lden, Lnight which usually is presented via the appropriate noise maps. However, there are cases when together with the calculation model the direct acoustic measurements are needed. The permanent noise monitoring for this purpose often is unpractical and a short-term noise level measurements become important. When long-term noise measurement (annual noise monitoring) is not applicable, the standard ISO 1996-2 allows carry out measurements in shorter time intervals than the specified one. For the case of the suburbia roads it is shown that exist the possibility to assess the one year descriptors using the data coupled from the few hours’ measurements only. As shown in paper it based on the statistics of traffic flow data for heavy and light transport (intensity, speed) as well as on the measured statistics of sound exposure levels of vehicle passing bys. For the urban traffic noise, as was shown by the statistical analysis of one year experimental data, at least one whole-day measurements are needed. In both cases chosen short-term interval or chosen whole-day must satisfy so-called representative measurement conditions. © 2017 2017The TheAuthors. Authors. Published by Elsevier © Published by Elsevier Ltd. Ltd. This is an open access article under the CC BY-NC-ND license Peer-review under responsibility of the organizing committee of the 10th International Scientific Conference Transbaltica 2017: (http://creativecommons.org/licenses/by-nc-nd/4.0/). Transportation and Technology. Peer-review underScience responsibility of the organizing committee of the 10th International Scientific Conference Transbaltica 2017 Keywords: vehicle noise, transport categories, sound exposure, representative time interval, short-term measurements
* Corresponding author. E-mail address: [email protected]
1877-7058 © 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 10th International Scientific Conference Transbaltica 2017
doi:10.1016/j.proeng.2017.04.421
615
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
1. Introduction The main descriptor that specifies the noise impact in the environmental living sites is introduced by DIRECTIVE 2002/49/EC [1] the annually averaged composite day-evening-night 24-h rating level Lden. In the recommendations provided by World Health Organization (WHO) [2] for noise impact assessment on the human health apart Lden descriptor the annual average night noise equivalent level Lnight is dealt also. In Lithuania formula for Lden determination since 2016 [3] takes a following view: ⎡1 Lden = 10 lg ⎢ 12 ⋅ 10 Ld / 10 + 3 ⋅ 10( Le +5) / 10 + 9 ⋅ 10( Ln +10) / 10 ⎢⎣ 24
(
⎤
)⎥ , ⎥⎦
(1)
where Ld is a annual average of equivalent noise level for the day 12 h period, from 07:00 to 19:00; Le is analogous descriptor for evening 3 h period, from 19:00 to 22:00 and Ln is a same descriptor for night 9 h period, from 22:00 to 07:00. Such annually averaged descriptors are very suitable for calculations and appropriately for noise maps design [4]. Using of noise maps gives a grate perspective for global estimation of environmental noise pollution to solve landscape planning tasks [5]. Noise mapping mainly based on the calculations, but may be accomplished by measurements. In used [6] and new developed [7, 8] methods the possible realizations of noise mapping calculations are described. However, there are cases when the direct acoustic measurements in some specific noise sensitive environment point are needed to confirm or not the implementation of designed measures (noise barriers construction, building façade sound insulation improvement, speed limiting, etc.) for noise abatement in these areas. The additional verifications of noise mapping results are needed for adjustment parameters for the calculation procedure also. The absence of the noise maps for interested site or e.g. the necessity to evaluate the demands for the newly designed building façade during few days duration are also require direct measurements. The situation with annual noise assessment using day-evening-night descriptor Lden is complicated due to non-stable whole-day environmental noise levels as shown in Fig. 1 and season climatic influence on the noise generated by road traffic.
Fig. 1. Typical view of whole-day time-history of environmental noise.
Some aspects of annual Lden assessment from measurements are discussed in [9−12]. In presented work two main cases of road traffic flow generated noise measurement procedures attended for the annual rating level Lden assessment are studied. The first [10] is a case when the statistic data about single vehicles passing bys are available from in-situ acoustic measurements data and the second one is an alternative case when Lden assessment may be carried out using 24-hours whole-days monitoring only [9, 11, 12]. The first case is typical for suburbia vehicle traffic flow and second one − for urban traffic flow.
616
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
2. Suburbia road traffic flow In this case exit a possibility to estimate annual Lden value by carrying out short-term measurements of traffic flow parameters in the interested living environment point nearby the suburbia road. To realise this assumption the following conditions for measurements must be fulfilled. 1. Traffic flow parameters such as an average annual speed and amount of light and heavy transport (in Lithuania two categories of road transport are taken into consideration: light and heavy) for rating time intervals 12 h day, 3 h evening and 9 h night must be available. 2. Before measurements it must be sure that weather conditions will be representative as it was stated in ISO 1996-2 [13]. At least the road surface must be dry; wind speed – less than 3 m/s and upwind of the source must be avoided. Other ground and weather conditions as ground surface type, air temperature and humidity, temperature gradients may be followed by ISO 1996-2 recommendations. 3. Measurement time period must be chosen in such manner that the remarkable part of single vehicle passing bys may be clearly identified on the time history record of sound levels as shown as examples in Fig. 2. So from enlarged 5 min. interval presented in Fig. 1b is clearly seen that practically all passing bys may be identified and their sound exposure levels (SEL) may be properly determined. The duration of measurement time must be planned so that coupled statistics of passing bys would be large enough to determine average SEL value of every vehicle category. By ISO 1996-2 the minimum registered SEL values for every transport category shall be 30 and by statistical method presented in ISO 11819-1 [14] for road surface impact assessment on traffic noise the minimum registrations shall be 100 and 80 for light and heavy transport correspondingly. It means that for measurement time optimization the density of traffic flow must be considered.
a)
b)
Fig. 2. Common view of recorded vehicle passing bys sound level time history (a) and enlarged 5 min. time history (b).
In first 1−3 items are described the preliminary conditions for measurements. Now analyze the conditions concerned measurement procedure itself. 1. Noise level generated by road transport shall be registered (measured) simultaneously using two microphones first (reference microphone) is placed near the road (10 m from the centre line of the road) on the height 4 m and second one – in the interested point of living environment site. From data coupled on reference microphone the reference SEL values may be calculated using corresponding post processing operations. Additionally from site point data, the environmental correction for noise propagation from the source (road) to the site point may be determined properly considered all environmental peculiarities. This correction is calculated as a difference between equivalent levels on the both microphones.
617
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
2. In the noise measurement interval the vehicles speed must be checked for comparison to the annual average speed of light and heavy transport. 3. Analogously synchronous video registration of vehicles passing bys must be accomplished to assign the SEL values to appropriate category of vehicle. When all of above presented conditions are fulfilled the equivalent noise levels in rating time intervals needed for Lden calculations at the reference microphone location are determined from the formula.
(
⎡τ L / 10 L / 10 + kh ⋅ 10 AE ,h LAeq,T = 10lg ⎢ ref kl ⋅ 10 AE ,l ⎢⎣ T
)⎤⎥⎥ ,
(2)
⎦
where kl, kh is an average annual amount of light and heavy transport appropriately in rating time interval T (12 h – day or 3 h – evening or 9 h – night); LAE,l, LAE,h is determined from measurements SEL average values for light and heavy transport appropriately. The difference between equivalent sound levels registered simultaneously on both microphones (reference and interested point of environment) during the measurement gives a value of real environmental correction that must be subtracted from the Lden value determined for the reference microphone position. Note that the adequacy of obtained results depends on the level of measurement data representativeness. It means that registered road traffic data as speed, vehicle categories percentage must be close to the appropriate annual values for chosen measurement time period.
3. Urban road traffic flow for conditions of Lithuania
LDEN, dBA
For the case when the single passing bys are difficult to identify and consequently SEL values are not available, the permanent monitoring during the whole-days may be used for annual Lden estimation. The principles for measurement days choosing for annual estimations may be determined from at least annual measurement data collected. Such experimental measurements are accomplished in the site point of Vilnius town placed 265 m meters from main arterial roads, where stationary urban traffic noise dominates in day 12-h time interval. The microphone was placed near façade at the 4 m height. Sound propagates from the road to the microphone as a direct line without any obstructing buildings. The influence of the season factors on Lden values for each month of the year are shown in Fig. 3 where the distribution of rating level Lden for free field conditions (façade reflection corrections of 3 dB are applied) by months is presented. 54 53 52 51 50 49 48 December
November
October
September
August
July
June
May
April
March
February
January
Fig. 3. Dependencies of free field Lden values by months with respect to the annual value of 52 dBA (dashed line).
So the monthly Lden levels clearly depend on the weather conditions, which differ with the seasons and are scattered by about 4 dBA from 49.7 dBA in January to 53.6 in October/November. The smallest noise levels in January and February are involved by low air temperature and snowy weather conditions, that follows less road
618
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
traffic and higher sound absorption by snow covering. The higher levels in the autumn months October and November may be explained by the most rainy and windy weather conditions. Annually representative results are obtained in spring and as well as in summer months’ June and August were characterized by mostly dry weather conditions. The statistical processing of one year coupled data allow to estimate the accuracy (uncertainty) of annual Lden determination using shorter time interval as one week or one day duration. Uncertainty is calculated using appropriate values of standard deviation multiplied on the coverage coefficient equal to 2 that correspond to the confidence interval with a 95 % confidence level of probability. The numerical results of annual Lden value assessment are presented in Table 1. Table 1. Estimation of yearly Lden value for chosen long-term time interval’s. Long-term reference time interval
Energy average, dBA
Standard deviation, dBA
Uncertainty interval, dBA
Month (from 12 months)
52.2
1.12
(−2.4; +2.1)
Week (representative)
52.2
0.88
(−1.8; +1.7)
Whole-day (arbitrary)
52.2
1.82
(−4.0; +3.3)
Whole-day (representative)
52.3
1.17
(−2.5; +2.2)
The uncertainty limits in calculations are not symmetrical in regard to the average values of Lden because the last ones are calculated on the energy mean principle and statistical processing may be based on the arithmetic mean only. Results presented in Table 1 shows that for traffic flow noise case acquiring sound pressure level data allows to assess the annual Lden from single representative whole-day measurements with about 2.5 dBA uncertainty. The representative conditions in this section are similar to presented in section 2.
4. Conclusions It is shown that in case when single vehicle passing bys may be identified for the most of all passing bys during the certain measurement time interval (that is typical for suburbia roads) exist a possibility to assess the annual Lden value applying short-term (till one-two hours) acoustic measurements. It based on availability of the statistics of traffic flow data for heavy and light transport (intensity, speed) as well as on the measured statistics of sound exposure levels of vehicle passing bys. The adequacy of obtained results depends on the level of representativeness of measured data. In the case when vehicle passing bys can’t be identified properly (that is typical for urban traffic) at least a one whole-day measurements are needed. The one year experimental measurement results show that annual Lden value may be assessed with about 2.5 dB expanded uncertainty using one representative whole-day acoustic measurements. One representative week (or 7 not consecutive days) measurements give 1.8 dB value of expanded uncertainty. In both cases chosen short-term interval or chosen whole-days must satisfy so-called representative measurement conditions.
References [1] Directive 2002/49/EC of the European Parliament and of the Council of 25 June 2002 relating to the assessment and management of environmental noise. [2] WHO Regional Office for Europe, 2011, Burden of disease from environmental noise, ISBN: 978 92 890 0229 5. Available from Internet: (http://www.euro.who.int/data/assets_pdf_file_0008_136466_e94888.pdf) [3] LR Triukšmo valdymo įstatymo Nr. IX-2499 pakeitimas (LR Noise regulation law amendement), TAR, 2016-05-24, Nr. 13907. [4] G. Zambon, R. Benocci, G. Brambilla, Cluster categorization of urban roads to optimize their noise monitoring, Environ Monit Asses 2016;188:26. doi: http://dx.doi.org/10.1007/s10661-015-4994-4 [5] A. Kaklauskas, E. K. Zavadskas, J. Šaparauskas, Conceptual modeling of sustainable Vilnius development, Technological and Economic Development of Economy 15(1) (2009) 154−177. [6] C. Steele, A critical review of some traffic noise prediction models. Applied Acoustics 62(3) (2001) 271–287. [7] E. A. King, H. J. Rice, The development of a practical framework for strategic noise mapping, Applied Acoustics 70(9) (2009) 1116–1127.
Aleksandras Jagniatinskis et al. / Procedia Engineering 187 (2017) 614 – 619
[8] J.-F. Hamet, F. Besnard, S. Doisy, J. Lelong, E. le Duc, New vehicle noise emission for French traffic noise prediction,. Applied Acoustics 71(9) (2010) 861–869. [9] E. Gaja, A. Gimenez, S. Sancho, A. Reig, Sampling techniques for the estimation of the annual equivalent noise level under urban traffic conditions, Applied Acoustics 64(1) (2003) 43−53. [10] A. Jagniatinskis, B. Fiks, M. Mickaitis, Statistical assessment of environmental noise generated by road traffic, Transport 26(1) (2011) 96– 105. [11] A. Jagniatinskis, B. Fiks,. Assessment of environmental noise from long-term window microphone measurements, Applied Acoustics 76(2) (2014) 377–385. Available from Internet: http://dx.doi.org/10.1016/j.apacoust.2013.09.007 [12] D. Geraghty, M. O’Mahony, Investigating the temporal variability of noise in an urban environment, International Journal of Sustainable Built Environment 5 (2016) 34–45. [13] ISO 1996-2:2007 Acoustics − Description, measurement and assessment of environmental noise − Part 2: Determination of environmental noise levels. [14] ISO 11819-1:1997 Acoustics − Measurement of the influence of road surfaces on traffic noise − Part 1: Statistical Pass-By methods.
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