Construction Noise And Vibration Impact On Sensitive
Proceedings of ACOUSTICS 200923-25 November 2009, Adelaide, AustraliaConstruction noise and vibration impact on sensitivepremisesCedric RobertsEngineering and Technology Division, Department of Transport and Main Roads, Brisbane, Queensland, AustraliaABSTRACTConstruction noise and vibration must be considered an essential part of the development of any transportation facility. Roadand tunnel construction is often conducted in close proximity to residential and commercial premises and should be predicted, controlled and monitored in order to avoid excessive noise and vibration impacts. Construction noise and vibrationcan threaten a project's schedule if not adequately analysed and if the concerns of the community are not addressed and incorporated.AIRBORNE NOISEConstruction over the length of a project can take place 24hours a day and for major projects, in excess of 2 to 3 years.Construction equipment can operate in very close proximityto residential and commercial (and even industrial) premises.Many items of equipment can be found operating at any timethroughout a project. Equipment types range from mobilecranes, pile drivers, jackhammers, dump trucks, concretepumps and trucks, backhoes, loaders, dozers, rock-breakers,rock drills, pile boring machines, excavators, concrete andchain saws, and gas and pneumatically powered hand tools.An additional factor of great importance is the presence oflow frequency noise ( 200 Hz) in the source sound spectraof many items of equipment for which the 'true' annoyancecapability at sensitive receptors is not reflected either in themeasurement or prediction using the overall A-weightedsound pressure level, or dB(A).GROUND VIBRATIONThe total attenuation of vibration from an item of construction equipment to a receptor is estimated from the spreadingloss, a value dependent on whether the source of vibration isconsidered a point, line or planar source, attenuation due tointernal losses in the soil and rock, being a function of lossfactor η, velocity of propagation c, frequency of the vibrationand distance to the receptor and attenuation due to changes insoil or rock along the propagation path, being a function ofmechanical impedances of individual differing rock components. Mechanical impedance is derived from the density ofthe various media and longitudinal wave speeds for eachmedia.Wave propagation is usually surface or Rayleigh (orR-wave) type. Here again the perception of ground-bornevibration outside and especially inside premises is of a lowfrequency character.This paper describes methods adopted to estimate the overallnoise level and airborne spectra at the boundary of sensitivepremises and within these premises using various softwaremodelling packages applied to a typical road making construction project. The indoor receptor levels are then compared to acceptable criteria. Ground-borne vibration at theboundary of premises is compared to established vibrationperception evaluation criteria.INTRODUCTIONConstruction noise and vibration issues must be consideredan essential part of the assessment of the development of anyAustralian Acoustical Societytransportation facility. Road and tunnel construction is oftenconducted in close proximity to residential and commercialpremises and associated noise and vibration should be predicted, controlled and monitored in order to avoid excessivenoise and vibration impacts. Construction noise and vibrationcan threaten a project's schedule if not adequately analysedand if the concerns of the community are not addressed andincorporated.In general a project's schedule can be maintained by balancing the type, time of day and duration of construction activities: adhering to local or state noise control requirements andbeing proactive to community concerns.Airborne noiseConstruction over the length of the project can take place 24hours a day. Construction equipment can operate in veryclose proximity to residential and commercial premises.Many items of equipment can be found operating at any timethroughout the project. The full gambit of equipment typesare used such as mobile cranes, pile drivers, jackhammers,dump trucks, concrete pumps and trucks, backhoes, loaders,dozers, rock-breakers, rock drills, pile boring machines, excavators, concrete and chain saws, and gas and pneumaticallypowered hand tools.Typical construction equipment is shown in Figure 1.Figure 1. Typical construction equipmentSource: (FHWA 2006)Noise control specifications can contain both relative noisecriteria limits at identified noise sensitive receptor locations,as well as absolute noise emission limits for all equipmentused on site. The noise specification boundary line criterionis primarily a relative criterion in which construction-induced1
Proceedings of ACOUSTICS 200923-25 November 2009, Adelaide, AustraliaLAeq noise levels in general cannot exceed baseline (preconstruction) LAeq noise levels by more than 5 dB at identifiednoise sensitive receptor locations. While an increase of 5 dBmay be noticeable, it should not present an unacceptablenoise hardship condition.An absolute noise criterion is applied to generic classes ofheavy equipment to limit their noise emission levels. Equipment specific A-weighted LAmax noise limits in dB(A) expressed at a reference distance of 15m are defined in theNoise Code similar to those given in Table 2.Baseline LAeq noise levels must be established prior to construction operations in accordance with the draft ConstructionNoise and Vibration Code (CNVC 2009) which requires collection of at least two non-consecutive weekday 24 hournoise readings as well as one Sunday noise reading at specified noise receptor locations throughout the construction area.These baseline LAeq noise readings are then reduced into daytime, evening, and night-time average levels and used to establish boundary line noise criteria limits by adding 5 dB, orby defaulting to the higher LAeq option (where existing background ambient noise level exceeds the standard noise limits)during the relevant time period specified in the Noise Code.Blasting12594*1Standard noise limits for general construction during restricted hours at residential receptors are given in Table 1.Crane (mobile116851638t Bulldozer1188740Impact12695*20Rock drill1168520Dump truck115844035t 8540EquipmentSoundLAmaxAcousticDescriptionPower Levelnoise limitUsageat 15m,FactordB(A) re. 1dB(A)picowatt%or stationary)Time PeriodGeneral construction activitiesLAeq,15min dB(A)PileDriver (dieselDuration of ActivityDaytime, restrictedor period,6055506.00pm to 10.00pm,on any der10.00pm to 7.00amon any day.Table 2. Typical construction equipment noise emissioncriteria limitsTable 1. Standard noise limits for restricted hours*Indicates impactive deviceRestricted hours means the period between 6.00pm and7.00am Monday to Friday and 1.00pm to 12.00 midnightSaturday and at any time on a Sunday or a Public Holiday.Standard working hours allow noise limits 10 dB(A) greaterthan those presented in Table 1 for medium to long term activities.These emission limits are achievable but are conservativelyset as low as possible in order to require equipment to be wellmaintained, and often requires some form of source noisecontrol. Each and every item of equipment should be precertified by the contractor's acoustical engineer to pass theirrespective 15m noise emission limit before the equipment isallowed to work on site.Short term construction and maintenance activities are thosewhich would affect any one noise or vibration sensitive sitefor up to 14 days, medium term for more than 14 days and upto 20 weeks while long term activities exceed 20 weeks butless than18 months.2The 'Acoustic Usage Factor' represents the percentage of timethat a particular item of equipment is assumed to be runningat full power while working on site. The influence of idlingnoise may be disregarded when the difference between theAustralian Acoustical Society
Proceedings of ACOUSTICS 200923-25 November 2009, Adelaide, Australiaoperating equipment noise and the idling noise is more than10 dB(A).Thus, a contract specification can include two types of noisecriteria limits, relative boundary line limits and absoluteequipment emissions limits, both of which should be complied with by the contractors at all times. Consequently, ifmeasured or anticipated construction noise limits exceed theallowable noise criteria limits, then noise mitigation measuresare warranted and must be implemented prior to and maintained during associated work activities.An added concern is that of the impact of low frequencynoise ( 200 Hz) especially inside residential properties. Thetraditional methods of using LAeq and LAmax are not appropriate for such situations. This paper applies the draft EcoaccessGuideline ‘Assessment of Low Frequency Noise’ (LFN 2008)to assess the impact of low frequency noise from earthmoving equipment and the criteria set out in this document.Drive-byCaterpillaron haul-657BroadscraperEarthworksFront dband noiseTotal89Noise levels at receptor locations can be calculated by usingaccepted point-source strength propagation algorithms suchas that below, summed over all operating equipment:LAeq,1hPREDICTION METHODSLAeq,15min LAmax,15m - 20 log10 (d/15) 10 log10 (U.F.%/100)–ILbar – 10G log10 (d/15), dB(A)(1)where LAmax,15m is the A-weighted noise emission limit forthe equipment at 15m (see Table 2).d distance between the equipment and the receptor in mU.F.% time averaging equipment usage factor in % (seeTable 2)ILbar A-weighted insertion loss of any intervening barrier/screen/enclosure, computed separately in dB(A)G ground factor constant due to topography and groundeffectsFor sound transmission over hard earth, G 0Source: (FHWA 2006)Case Study SchemeA scenario is chosen to include a range of earthworks operations and construction plant. The plant used in the study werea twin-engined motorized scraper, off-highway dump truck,bulldozer, excavator and front end loader. The noise is propagated over hard earth and there are no intervening barriers.Earthworks is likely to occur for 4 months (medium term). Aprediction is made of LAeq,1h external to an apartment located30m away from the centre of construction operations.Table 3. Prediction of noise level at apartment from earthmoving operationsLow frequency noiseThe internal overall dB(A) and low frequency (LF) noiseclimate within a typical apartment building was determinedfrom the sound insulation properties of two typical spacedividing building elements comprising the external façadeand from the sound absorptive properties of internal treatment of the apartment. Other noise attenuation measures liketemporary external barriers close to operating equipment andtreated construction plant and equipment were not consideredin this determination.The frequency spectra of the construction equipment in termsof 1/3rd octave band levels and overall dB(A) was establishedby considering the following sources of information : (TRRL1976) and (CC&AA 2005).The results of this information as source spectra for construction equipment in 1/3rd octave bands Z-weighting, overalldB(Z) and dB(A) in terms of LAeq,2min is presented in Table 4.Z-weighting is defined in IEC 61672-1, the latest international standard for sound pressure level measurements. Itstands for zero-weighting, or no weighting; i.e., a flat measurement with equal emphasis of all frequencies.A sampling period of 2 minutes was adopted for this LFNinvestigation as source data was reported for this time period.Predictions at this location are presented in Table actorLAeq%Australian Acoustical Society3
Proceedings of ACOUSTICS 200923-25 November 2009, Adelaide, Australia1/3rd octaveExcavatorFront endCaterpillarband fre-on @10m@15m899586(Hz)31.5Figure 2. Front end ource: (CEN 1985)Figure 3. Hydraulic excavator and 77 tonne truckSource: (Griffin Coal 1982)Figure 4. Caterpillar ScraperdB(Z)112120103dB(A)10611490Source: (CEN 1985)Noise Propagation and NR estimation* Indicates prominent tonalityTable 4. Source spectra and overall noise levelsFor predictions of building component sound reduction andaverage absorption coefficients within living areas the spectrafrom Table 4 was adopted demonstrating the greatest soundenergy within the 50 Hz to 250 Hz 1/3rd octave bands, asthese frequencies are the most prominent (and probably themost annoying), and sometimes exhibit a characteristic tone(as demonstrated by the Caterpillar Model 631B scraper).The overall Z and dB(A) values were measured or derivedfrom the full audio frequency range of 31.5 Hz to 10 kHz,although not all of these frequency bands are reported in Table 4. The items of construction equipment chosen for theprediction of LF intrusion were the front end loader driving at10m (Figure 2), the excavator (Figure 3) and the scraper operating at 15m (Figure 4).4Internal noise levels were calculated based upon point sourceemission, free field sound propagation, external façade noiseattenuation and average absorption coefficients for internaltreatments. Determinations of the noise reduction (NR), overall dB(A) rating and Z-weighted spectra within an apartmentthen require complex calculations within each of 18 1/3rdoctave frequency bands over the range of 100 Hz to 5kHz.Calculations of the sound reduction for the additional threecentre frequencies - 50, 63 and 80 Hz were derived from themass law for homogenous panels and the double panel withconnections theory.For this reason four independent computer programs developed as Excel spreadsheets were used to determine: the LF noise attenuation of the three sources of construction equipment over distance the sound reduction within 1/3rd octave bands of anexternal partition composed of different building elements eg. wall, windows and doors with different areas the average sound absorption coefficients of variousinternal building elements and surface treatments within1/3rd octave bands, assuming even distribution of absorbing material and neglecting air absorption, andAustralian Acoustical Society
Proceedings of ACOUSTICS 2009 the noise reduction through the building facade, internalZ-weighted sound pressure levels as a function of frequency, the overall equivalent sound pressure level,LAeq,2min and low frequency descriptor, LpALF23-25 November 2009, Adelaide, AustraliaCombination #Description of oefficientat 125 HzR1Ceiling:Stramit/Woodtex50mm coarse grain No11 panel0.570.5Walls:Stramit/Woodtex50mm coarse grain No11 panel0.570.5Window: EBS Ref No.7020-40.15 (est)0.350.550.081.020.65Characteristics of sensitive premisesAn apartment living area, in this case a bedroom of typicaldimensions with a single window incorporated, was assumed.The dimensions of the bedroom facing the three noise sourceswere taken as 4.6m (L) x 3.8m (B) x 3m (H) with a floorsurface area of 17.5m2. The dimensions of the room weretaken in the ratio 1(H) : 1.28 (B) : 1.54 (L) in order to achievemaximum sound diffusion within the room, to distribute modal frequencies in the best way and so avoid resonance modeswhich might occur at the dominant low frequencies in thethree construction equipment noise signals.(Stramit1984)(EBS1973)The window size was taken as 10% of the floor area or1.75m2 and a standard window size of 1.5m (B) x 1.2m (H)adopted in computer modelling.Choice of building componentsTwo external building materials were chosen, based on theirSTC (or RW rating) and sound reduction predominantly at thelow frequencies of 50 Hz to 200 Hz. Internal treatments werealso selected based on a high noise reduction coefficient(NRC) and absorption coefficients over the frequency rangefrom 50 Hz to 160 Hz.Two scenarios were set up in terms of composite buildingelements in the external façade and internal absorption treatments. The computer models were then run each time withthe aim of achieving the highest noise reduction in terms ofdB(A). At the same time, checks were made as to the noisereduction achieved within the 50 Hz to 200 Hz 1/3rd octavefrequency bands compared with LF noise limits. The configurations were chosen in an attempt to compare the maximum dB(A) and LF noise reductions achieved for the twoconfigurations.Internal noise levelsThe predicted internal noise levels were compared to: a sleepdisturbance criterion of 35 dB(A) LAeq for steady noise, auditory perceptions in terms of Z-weighted sound pressure levelversus 1/3rd octave frequency bands, annoyance rating fornon-tonal, low frequency noise in the domain less than 160Hz using descriptor LpALF and; annoyance assessment fortonal noise exhibited by the scraper at centre band 80 Hz.SELECTED SCENARIOS10-76-13mm(Mec Eng1982)R5Floor: Heavy carpet on40 oz hairfelt or foamrubber laid on concreteCeiling : Stramit Roof(Stramit1984)and Ceiling SystemRefer SA.17.Other components asfor R1 but no windowTable 5a. Combinations of building elements and absorptivetreatments – receiving areaCombination #DescriptionRWSoundreductionat 125 HzWall: EBS RefNo. 6107. Claybricks, rendered13mm bothsides4533(EBS 1973)Window: EBSRef No. 7020-4,10-76-13mmspacing4636P5Wall: CSRGyprock Masonry–WallSystem. No.721with no window6750P1(EBS 1973)The following two combinations of building elements andabsorptive treatments were selected for modelling:(CSR Man)Table 5b. Combinations of building elements and absorptivetreatments- dividing partitionAustralian Acoustical Society5
Proceedings of ACOUSTICS 200923-25 November 2009, Adelaide, AustraliaGround vibrationD distance from pile driver to the receiver in mWave propagation is usually surface or Rayleigh (or R-wave)type (CALTRAN 2004). Most energy is transmitted in the Rwave which is the most significant disturbance along thesurface of the ground, and it may be the only clearly distinguishable wave at large distances from the source. Accordingly, propagation of vibration from construction sources,including pile driving, is typically modelled in terms of Rwaves.Eref 48,852 Joules (rated energy of reference pile driver)The perception of ground-borne vibration within premises isof a low frequency character. Typical vibration from transportation and construction sources falls in the range of 10-30Hz and usually centres around 15 Hz. Vibratory pile driversgenerate continuous vibrations with operating frequenciestypically between 25 and 50 Hz. Vibratory rollers operate inthe range 26 to 66 Hz (high setting) and 26 to 55 Hz (lowsetting). (CALTRAN 2004). For the purposes of assessingvibration effects on people and structures, use of a frequencyindependent material damping coefficient is supported by thefact that damage levels in terms of velocity in the frequencyrange of 1-80 Hz tend to be independent of frequency.Eequip rated energy of impact pile driver in Joulesn 1.1 is a value related to the vibration amplitude ratethrough ground.Vibration impact estimates may be refined further by usingvalues of 'n' that are based on soil type classification or soilconditions at a site as illustrated in Table 7.Description of soil materialn, slope or attenuationrateTable 6 presents typical values of vibration for some construction equipment sources in terms of peak particle velocity(ppv) expressed as mm/sec.value for geometricand material dampingWeak or soft soils: loose soils,1.4sand, recently ploughed ground,top soil (shovel penetrates easily)Competent soils: most sands,Reference ppv at 7.6msandy clays, gravel, silts, weath-(mm/sec)ered rock (can dig
measurement or prediction using the overall A-weighted sound pressure level, or dB(A). GROUND VIBRATION The total attenuation of vibration from an item of construc-tion equipment to a receptor is estimated from the spreading loss, a value dependent on whether the source of vibration is cons
Transit noise and vibration analysis, noise and vibration impact criteria, noise and vibration mitigation measures, environmental impact assessment, National Environmental Policy Act compliance. 15. NUMBER OF PAGES 274 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT Unclassified 18. SECURITY CLASSIFICATION OF THIS PAGE Unclassified 19.
Noise Figure Overview of Noise Measurement Methods 4 White Paper Noise Measurements The noise contribution from circuit elements is usually defined in terms of noise figure, noise factor or noise temperature. These are terms that quantify the amount of noise that a circuit element adds to a signal.
Construction Noise and Vibration Plan Page 5 of 25 John Holland IN CONFIDENCE 1. Introduction 1.1 Purpose and application This Construction Noise and Vibration Management Sub Plan (CNVMP) is a key element of the overall Construction Environmental
The Noise Element of a General Plan is a tool for including noise control in the planning process in order to maintain compatible land use with environmental noise levels. This Noise Element identifies noise sensitive land uses and noise sources, and defines areas of noise impact for the purpose of
november 2011 v1 olume 1 section 3 Part 7 hD 213/11 2. noise anD vibration – uK hiGhwaYs Definition of noise and vibration 2.1 Traffic noise is a general term used to define the noise from traffic using the road network. A traffic stream is made up of a variety of vehicle types which have their own individual noise sources. Close to a
noise and tire noise. The contribution rate of tire noise is high when the vehicle is running at a constant speed of 50 km/h, reaching 86-100%, indicating tire noise is the main noise source [1]. Therefore, reducing tire noise is important for reducing the overall noise of the vehicle and controlling noise pollution [2].
7 LNA Metrics: Noise Figure Noise factor is defined by the ratio of output SNR and input SNR. Noise figure is the dB form of noise factor. Noise figure shows the degradation of signal's SNR due to the circuits that the signal passes. Noise factor of cascaded system: LNA's noise factor directly appears in the total noise factor of the system.
Figure 1: Power spectral density of white noise overlaid by flicker noise. Figure 2: Flicker noise generated from white noise. 1.1 The nature of flicker noise Looking at processes generating flicker noise in the time domain instead of the frequency domain gives us much more insight into the nature of flicker noise.
