1. A comparison between different traffic noise forecasting methods and experimental data.
Adolfo Sabato, Alessandro Sabato, Alfredo Reda
Department of Mechanics, Università della Calabria
Laboratory of TCA, Rende (Cs) – Italy
August 21st, 2012 – Broadway N Room
Marriott Marquis Times Square, New York City, NY - USA

2. Forecasting methods from Directive 2002/49/EC
- NMPB (France):
SPL from traffic up to 800m from roadway and 2m above ground level.
- CRTN (UK):
SPL from traffic in streets distant less than 300m, with wind speed up to 2.5ms-1.
LA10= 10log Q + 33log (v /v) + 10log (1 + 5P/v) – 27.6
Q= vehicles per hour; v= vehicles average speed; P=heavy-vehicles rate

3. Experimental LAeq (in point A):
Experimental data vs model data
Location: Crotone (KR) - Italy
Length: 24 hours
Microphone:4m above roadway
SPL: Fast, A-weighted
Experimental LAeq (in point A):
Day reference time: 68dB(A)
Night reference time: 63dB(A)

4. Experimental data vs NMBP data
LAeq,DAY (point A):
Model: 75 – 80dB(A)
Experimental: 68 dB(A)
LAeq,NIGHT (point A):
Model: 65 – 70dB(A)
Experimental: 63 dB(A)

5. Experimental data vs CRTN data
LAeq,6-22 (point A):
Model: 72 – 76 dB(A)
Experimental: 68 dB(A)
LAeq,12-13 (point A):
Model: 76 – 80 dB(A)
Experimental: 69 dB(A)

6. Extra information deducible from experimental data
Traffic is not the only annoying source
Mistakes during setting of parameters phases
Location: Rende (CS) - Italy
Length: 7 days
Microphone: 4m above roadway
SPL: Fast, A-weighted

7. Extra information: percentile levels
Some information can be deduced only with particular analysis
Between 3AM and 4 AM LA10 plunges, but LAmin and LA99 are constant
TRAFFIC IS NOT THE ONLY SOUND SOURCE
Night reference time – April, 20th 2012
LA10 falls
Day/night transition
LA50 plummets
Traffic decreases
LAmin ~ LA99 and parallel to LA10 and LA50
TRAFFIC IS THE ONLY SOUND SOURCE
Night reference time – April, 22nd 2012

8. Extra information: percentile levels
LAmin and LA99 do not follow LA10 trend
TRAFFIC IS NOT THE ONLY SOUND SOURCE
Day reference time – April, 25th 2012
LMAX hits a peak and influences LAeq which overcomes LA10
Impulsive energetic events
LMAX hits a peak and does not influence LAeq
Singular energetic events

9. Percentile levels: further analyses
Location: Rende (CS) - Italy
Length: 1 hour
Microphones:4m above roadway
SPL: Fast, A-weighted

10. Percentile levels: further analyses
Roundabout: LAeq = 65.5 dB(A)
Traffic lights: LAeq = 66.5 dB(A)
Sound characteristics due to road traffic (LAmin and LA50 trend)
Sound characteristics even due to other sources
From to traffic flow is stable in the roundabout, whereas it is erratic, even with a smaller number of vehicles, near the traffic light that slows down the flow.

11. Conclusion
Forecasting models can be a powerful tool to conduct environmental analyses in the prevision of overall sound characteristics of an area.
On the other hand their results are affected of too many uncertainties to be used alone to plan noise remediation actions.
Failure can be due to mistakes made during setting of parameters and analyses phases.
Measurement campaigns allow knowing a greater number of information that may lead to more accurate and efficient planning choices.
When a remediation plan should be done it is better to schedule it by using data coming from experimental measures rather than rely on forecasting methods only.

12. Thank you