Reducing Traffic Noise with Quieter AC Pavements By Paul R. Donavan 36 th Annual ROCKY MOUNTAIN Asphalt Conference & Equipment Show
Reducing Traffic Noise with Quieter AC Pavements What s the interest in quieter pavements? What examples are there of quieter pavement applications? What makes pavement quieter? How long does pavement stay quieter? How does performance vary?
Drivers of Quiet Pavement Interest Public concern over noise from freeways Extensive use of sound walls for noise abatement 1800 km in US
$$$ $2+ million per mile Can not be used everywhere Limits future highway expansion Not necessarily effective Blocks views
ADOT Application of Quieter Pavement 79 dba 70 dba Original Uniform Transverse Tine 1 Rubberized AC Overlay
Interest in Quiet Pavement Questions: Does it Last? Does it work for a traffic mix?
I-80 Pavement Project Location: I-80 just east of Davis and west of Sacramento, CA Traffic: 140,000 ADT (almost 10% trucks) Existing - Aged DGAC surfacing Quiet Overlay - Applied OGAC in July 1998
Measurements & Environment Distant Microphone Locations at 140m Reference Microphone Locations at 20m
Old Asphalt Surface 78.6 db Initial Reduction 6.4 db 72.2 db New Quieter Overlay
On-Board Sound Intensity Measurement Measure of propagating energy from tire Rejects flow noise Directional Isolates tire/road noise Vehicle adaptability AASHTO, SAE, ASTM Standards Sound Intensity Vectors I = pu
OBSI Measurements Windscreens
Caltrans Data Base - California & Arizona 110 OG/RAC Pavements 109 PCC Pavements 108 DGA Pavements 107 Sound Intensity Level, dba 106 105 104 103 102 101 100 99 98 97 96 95 94
ADOT/FHWA Arizona Quiet Pavement Pilot Project 185 km of freeway overlaid with ARFC FHWA allowed 4 db credit for pavement Long term research project to measure performance over 10 years Measurements 1. On-board measurements at each milepost 2. Wayside time average measurements
Pre & Post Overlay Site 3D ARFC Overlay (25mm Thick) Random Transverse Tined PCC
Noise Reduction with ARFC Overlay Tire/Pavement & Traffic Noise Reduction, db 14 12 10 8 6 4 2 0 Sound Intensity Site 3D 15m x 4m 15m x 1.6m 30m x 1.6m 76m x 1.6m Wayside Microphone Distance and Height
Reductions at Other Sites Tire/Pavement & Traffic Noise Reduction, db 14 12 10 8 6 4 2 0 Site 3E Site 3A Sound Intensity 15m x 4m 15m x 1.6m 30m x 1.6m Wayside Microphone Distance and Height
I-280 in San Mateo County, CA
New & Existing Pavements on I-280
I-280 in San Mateo County, California 1 to 2 db Quieter (Ground) 6 db Quieter RAC(O)
Las Vegas I-515 ROGFC Overlay
Las Vegas I-515 Pre & Post Levels 112 110 108 Original PCC New ROGFC Overall OBSI Level, dba 106 104 102 100 98 96 94 11.7 db Reduction 92 90 N-1 N-2 N-3 S-1 S-2 S-3
Pre & Post Rehabilitation Project
6½ db Reduction (OBSI)
Roadway 5½ db Reduction In Backyards
On the Road in Europe Noise Intensity Testing in Europe: The NITE Study
Scope First definitive comparison of European & US pavement 4 countries, 68 pavements Compliment to the AASHTO/FHWA Scan Objectives Measure the quietest pavement of all types Measure the range of pavements in use The NITE Project
Caltrans Data Base - California & Arizona 110 OG/RAC Pavements 109 PCC Pavements 108 DGA Pavements 107 Sound Intensity Level, dba 106 105 104 103 102 101 100 99 98 97 96 95 94
Sound Intensity Level, dba 110 109 108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 European Pavements at 97 km/h PA PCC DGA DLPA SMA
Sound Intensity Level, dba 102 101 100 99 98 97 96 95 94 Comparison of Quietest Pavements Europe California Arizona 93 92 DLPA 2/6 DLPA 4/8 PA 4/8 PCC (P/G) LA 138 OGAC LA 138 RAC ARFC
What Makes AC Pavements Quieter? Smaller aggregate size Less displacement input to the tire Other surface characteristics also important
Coarse & Fine SMA Surfaces 8/10mm 105.7 dba 0.8/1.5mm 99.7 dba
107 106 105 104 103 102 101 100 99 98 97 96 95 Stone Mastic Asphalt Surfaces of Varying Aggregate Size 0/5mm 0/3mm 0.8/1.5mm 0/8mm 0/8mm 0/11mm 0/8mm 0/14mm 8/10mm Sound Intensity Level, dba
Extreme Surfaces Chip Seals California SR 84 105.0 db 104.8 db Replica of California Pavement
Extreme Surfaces Fine Texture Caltrans Test Track 95.7 db 94.6 db Ultra-Smooth Test Track Pavement
What Makes AC Pavements Quieter? Smaller aggregate size Less displacement input to the tire Other surface characteristics also important Porosity Sound absorption in the pavement Reduction of some tire noise mechanisms
Porous & Non-Porous AC Surfaces 0/10mm Dense Grade 101.3 dba 0/10mm Porous 98.5 dba
Propagation of Tire Noise over Absorptive Pavement Potential: ~3 db Reduction
Typical 2-Layer Porous Asphalt the Netherlands Small Aggregate Size Coarse Aggregate Size
Double Porous Layer Asphalt Surfaces of Varying Aggregate Size 105 104 Sound Intensity Level, dba 103 102 101 100 99 98 97 96 95 94 DLPA 2/6 DLPA DLPA 4/8 DLPA 2/6 DLPA 4/8 DLPA 4/8
What Makes AC Pavements Quieter? Smaller aggregate size Less displacement input to the tire Other surface characteristics also important Porosity Sound absorption in the pavement Reduction of some tire noise mechanisms Added rubber content
Rubber & Non-Rubber OGAC of Similar Aggregate Size/Gradation OGAC 98.0 dba Rubberized OGAC 97.1 dba
What Makes AC Pavements Quieter? Smaller aggregate size Less displacement input to the tire Other surface characteristics also important Porosity Sound absorption in the pavement Reduction of some tire noise mechanisms Added rubber content Surface compliance?
Issues Acoustic Longevity Variation in pavement performance
Overall Sound Intensity Level, dba 104 103 102 101 100 99 98 97 96 95 94 Caltrans LA 138 AC Research Sites Oct 02 Oct 03 Oct 05 Oct 06 Oct 07 Oct-08 2½ to 3 db in 6 Years DGAC OGAC (75mm) OGAC (30mm) RAC BWC Test Pavement Surface Type
Sacramento I-5 RAC(O) Overlay
I-5 Sac RAC(O) Performance over Time 106 105 SOUTHBOUND NORTHBOUND 104 103 102 101 100 99 98 97 96 PCC Avg 12/2/2004 8/18/2005 8/15/2006 11/2/2007 8/14/2008 PCC Avg 12/2/2004 8/18/2005 8/15/2006 11/2/2007 8/14/2008 Overall Sound Intensity Level, dba
I-80 Davis Long-Term Performance 80 79 78 77 76 75 ~ 2 db in 10 years 74 73 72 71 70 69 68 Old DGAC New OGAC 1 Month 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Year Traffic Noise Level, dba
San Mateo I-280 Performance Overall Sound Intensity Level, dba 102 101 100 99 98 97 96 95 2002 2005 94 SB OGAC Shoulder SB RAC(0) Travel Lane NB RAC(0) Travel Lane
Performance of AZ ARFC over Time 86 84 Site 3D Traffic Noise Level, dba 82 80 78 76 74 72 70 68 66 Pre- Overlay 1 Year 1.5 Years 2 Years 2.5 Years 3 Years 3.5 Years 4 Years
Average Performance of AZ ARFC Overall Sound Intensity Level, dba 106 105 104 103 102 101 100 99 98 97 96 95 All Mileposts 94 PCC 2004 Mar 2005 Mar 2006 Nov 2006 Mar 2007 Oct 2007 Mar 2008 Oct 2008
Acoustic Longevity of PCC at Mojave 107 Ground PCC 106 Burlap Drag Longitudinal Tined 105 Overall OBSI Level, dba 104 103 102 101 100 99 98 97 Mar 03 Jun 03 Jun 05 Oct 08 Date of Test
100 99 98 97 96 95 94 Levels for Zebra Sections in the Netherlands Sound Intensity Level, dba A15 #1 A15 #2 A15 #3 A15 #4 A15 #5 A15 #6 A59 #1 A59 #2 A59 #3 A59 #4 A59 #5 A59 #6 Double Layer Porous 4/8mm ~ 2 db
Variation of ARFC Tire/Pavement Noise Source Levels at Arizona Site 3 s 100 Sound Intensity Level, dba 99 98 97 96 95 ~ 2 db 94 Site 3A WB Site 3A EB Site 3C-1 Site 3C-2 Site 3C-3 Site 3D WB Site 3D EB Site 3E SB Site 3E NB
104 103 Variation of RAC(O) Tire/Pavement Noise on I-5 in Sacramento Southbound Northbound Sound Intensity Level, dba 102 101 100 99 98 3+ db 97 96 Segment 1 Segment 2 Segment 3 Segment 1 Segment 2 Segment 3
Summary Reductions of 5 to 12 db possible Quietest pavements between US and Europe Perform almost equally Aggregate size & porosity patter Quieter AC performance can degrade at 0.2 to 0.5 db/yr Performance varies up to 2 to 3 db