《道路与桥梁建筑材料》课程授课教案（PPT讲稿）Asphalt Mixtures to reduce Traffic Noise

Asphalt Mixturesto reduce TrafficNoiseProf.Dr. Ir.Andre.A.A.MolenaarAugust31,2025TUDelftDelftUniversityofTechnology

Vermelding onderdeel organisatie August 31, 2025 1 Asphalt Mixtures to reduce Traffic Noise Prof. Dr. Ir. André. A. A. Molenaar

Main sources of noiserail trafficrecreationindustrybuildingactivitiesairtrafficroadtraffic051015202530[%]August31,2025TUDelft

Main sources of noise August 31, 2025 2 0 5 10 15 20 25 30 road traffic air traffic building activities industry recreation rail traffic [%]

Noiseexposedlandin Europe35%>55 dB(A)30%47-55dB(A)40-47dB(A)25%20%15%10%5%0%m9PAYRRAAugust31,2025TUDelft

Noise exposed land in Europe August 31, 2025 3 0% 5% 10% 15% 20% 25% 30% 35% B I L DNL GB F A PDK E GRIRL S FIN >55 dB(A) 47-55 dB(A) 40-47 dB(A)

TrafficnoiseTraffic noise is dominant source ofenvironmental noiseTyre-road noise determinestrafficnoiseOver30%ofthepopulationoftheEUisExposedto55dB(A)andhigherAugust31,2025?TUDelft

Traffic noise • Traffic noise is dominant source of environmental noise • Tyre-road noise determines traffic noise • Over 30% of the population of the EU is Exposed to 55 dB(A) and higher August 31, 2025 4

NoiseSound consists of sound waves with a wide variety ofwavelengths and pressure levelsSoundpressuretimeinterval1752804August31,2025TUDelft

August 31, 2025 5 Noise Sound consists of sound waves with a wide variety of wavelengths and pressure levels. Sound pressure time

Sound/noise1Soundconsistsof small,relativelyfast,changesintheatmosphericpressurewhich movesaswaves.The wave frequency determinesthe height of the tone.Importantfactors:sound pressurelevel andfrequencyWe cannot hear the very high and very lowtonesbut wecanfeelthem(paininears,vibrationonyourbelly)We don't hear all freguencies as egually loud.We hearsomefrequenciesbetterthanothers.August31,20252TUDelft

August 31, 2025 6 Sound/noise 1 • Sound consists of small, relatively fast, changes in the atmospheric pressure which moves as waves. • The wave frequency determines the height of the tone. • Important factors: sound pressure level and frequency. • We cannot hear the very high and very low tones but we can feel them (pain in ears, vibration on your belly). • We don’t hear all frequencies as equally loud. We hear some frequencies better than others

Lines of egual loudness2009080706050.03020We don't hear10anythingbelowthis levelCLD0060001252505001000200031,5631752004FrequenciesofspeechFrequentie,HzAugust31,2025NTUDelft

August 31, 2025 7 Lines of equal loudness Sound pressure level dB Frequencies of speech We don’t hear anything below this level

Sound/noise 2Becausethereisadifferenceinterms of energyof25x1012betweenwhat we canjusthearandwhat causes pain,we are usinglog-scales.We calculate the ratio of the log of the energyof the occuring changes inair pressure to thelog of the energy at what we can justhear.Thisratio is expressed in decibels (dB).Because our ear is not equally sensitive to eachfrequency,we apply a weighingfactor;thisresults in dB(A)August31,2025TTUDelft

August 31, 2025 8 Sound/noise 2 • Because there is a difference in terms of energy of 25 x 1012 between what we can just hear and what causes pain, we are using log-scales. • We calculate the ratio of the log of the energy of the occuring changes in air pressure to the log of the energy at what we can just hear. This ratio is expressed in decibels (dB). • Because our ear is not equally sensitive to each frequency, we apply a weighing factor; this results in dB(A)

Equivalentsound/noiselevelLeq = 10log( (1/T) J (p2efr/p2) dt)[Leq] = [dB(A)]August31,2025TTUDelft

August 31, 2025 9 Equivalent sound/noise level Leq = 10log{ (1/T)  (p2 eff/p2 0) dt} [Leq] = [dB(A)]

Sound/noise3Carsproduce noisebecause ofthe engine,exhaustsystem,loosecargoandtires.Drivingovertheroad surfaceresultsintirevibrationswhichresultsinnoise,Widetires,rough surface texture and a densesurface produce a higher noise level.Tire noiseisdominant above a speed of ca50km/h.10August31,2025TTUDelft

August 31, 2025 10 Sound/noise 3 • Cars produce noise because of the engine, exhaust system, loose cargo and tires. • Driving over the road surface results in tire vibrations which results in noise. • Wide tires, rough surface texture and a dense surface produce a higher noise level. • Tire noise is dominant above a speed of ca 50 km/h