Quiet Pavements

1. Quiet Pavements FHWA Environmental Conference June 27-29, 2006 Chris Corbisier, FHWA

2. Noise – Current Practice • Noise – unwanted sound from vehicles • Sources – Tires, engines, and exhausts • Barriers Minimum of 5 dBA noise reduction Effective from 200-400’ Cost > $1Million/mile Maintained in perpetuity

3. PAVEMENT • Pavement is sometimes mentioned as a factor in traffic noise. While it is true that noise levels do vary with changes in pavements and tires, it is not clear that these variations are substantial when compared to the noise from exhausts and engines, especially when there are a large number of trucks on the highway. Additional research is needed to determine to what extent different types of pavements and tires contribute to traffic noise.

4. PAVEMENT • It is very difficult to forecast pavement surface condition into the future. Unless definite knowledge is available on the pavement type and condition and its noise generating characteristics, no adjustments should be made for pavement type in the prediction of highway traffic noise levels. Studies have shown open-graded asphalt pavement can initially produce a benefit of 2-4 dBA reduction in noise levels. However, within a short time period (approximately 6-12 months), any noise reduction benefit is lost when the voids fill up and the aggregate becomes polished. The use of specific pavement types or surface textures must not be considered as a noise abatement measure.

5. Current FHWA Tire/Pavement Noise Mitigation Policy • Prohibits making adjustments for specific pavement types in prediction of noise levels • Only “Average” pavement type is allowed in TNM Pavement types: • DGAC, OGAC, PCC • Average pavement type: DGAC & PCC • Prohibits the use of pavement types/surface textures as a noise abatement measure • www.fhwa.dot.gov/environment/noise/qpppeml.htm

6. QP3 vs. Quiet Pavement Research • In a QPPP acceptable documentation is known, so • Pavement type can be used in TNM • Specific pavement types can be used as a mitigation measure • In "quiet pavement" research acceptable documentation is not known, so • TNM adjustments and pavement types as a mitigation measure can not be used. • These determinations will not be made until the "quiet pavement" research is completed.

7. QP3 vs. Quiet Pavement Research • The type of data gathered for both a QPPP and quiet pavement research are exactly the same. • This allows data for a specific pavement type from either source to be compared directly • This can help determine any correlation between pavement characteristics (e.g., texture or skid resistance), safety, durability, and noise reduction.

8. Arizona’s QPPP • Existing concrete loud, used ARFC as overlay for splash and spray, noticed noise reduction and loss of “whine” • Noise studies showing noise reduction lasted over time (documentation) • Chose 4 dB adjustment to predicted noise levels and used as mitigation • Overlaid 115 miles for $34 million • Heavy truck percentage is low • 15 million tires recycled since 1988

9. Tire/Pavement Noise Strategic Planning Workshop: Purdue Sept. 2004 • Participants – 45 from State DOTs, FHWA, Industry, and Academia • Presentations – Tire/pavement Noise Basics, Tire & Vehicle Manufacturers’ Perspective, European Scan, Current FHWA Pavement Policy, and State Experiences • Breakout sessions – Policy, Maintenance, Analysis, Design, Construction, and Research • Identification of gaps – 50 gaps, 8 receiving 25 or more votes

10. Knowledge Gaps • FHWA Noise Regulation and pavement policy • Measurement methodologies • Pavement design and optimization • Education and communication

11. Measurement Methodologies • Standardize Measurement Methodologies • Pass-by and Time Average – Wayside • Source – Close Proximity (CPX) or On-Board Sound Intensity (OBSI) • Expert Task Group – OBSI Draft Provisional Standard • CPX and OBSI Great for Ranking Pavements and QA/QC

12. 101 Workshop Objectives • Educate noise practitioners on the fundamentals of pavements and vice versa • Understand tire-pavement noise and how it fits into a larger framework • Understand the fundamentals of measuring and interpreting tire-pavement noise • Examine current practices for designing and constructing quieter pavements • Learn of research and policy directions related to tire-pavement noise

13. Tire/Pavement Noise Clearinghouse • Research – national and State level • Website provides information on the topic • Has links to websites providing information on quiet pavement studies • One stop shopping for current practice in quiet pavements

14. Future Tire/Pavement Noise Initiatives • TNM Pooled Fund Study • Allowing Existing Pavement Types in TNM to be Used • Recommendations/Findings from QPPP and QPR • NCHRP: • 1-44: Measuring Tire-Pavement Noise at the Source • 08-56: Truck Source Mapping • 01-67: Texture, Friction, Noise

15. National Tire/Pavement Noise Implementation Workshop • Second meeting to assess progress • Several gaps identified were: - Construction guidelines and best practices - Durability of the noise reduction - Cost/Benefits of Quiet Pavement - Standard tire for OBSI

16. Double Layer Porous Asphalt • Splash and Spray, Removes Water to Resist Hydroplaning, Other Possible Benefits • Quietest Technology we saw/heard in Europe • Quieter than Arizona’s ARFC by NITE study • Self-cleaning at highway speeds

17. QPR states • CA • CO • FL • MO • TX • WA • NV • NJ • OH

18. Final Considerations • Changes to policy, prediction methods, and public involvement • Pavement range by NITE study was up to 14 dB • Certain pavement types have shown up to 10 dB variation across single test section • Great Sound Wall of America