Appendix C: Amplifying Questions

Scope

The purpose of this scanning study is to document the state of the practice in design, construction, maintenance, and monitoring of quiet pavement systems, and identify new and innovative practices that may be evolving from past experience with existing systems. In addition, this U.S. study panel seeks information on noise policy, measurement methodologies, and monitoring systems. From April 30 to May 16, 2004, this panel wishes to visit nations that have successfully used new and innovative pavement technologies that have resulted in substantial reductions in tire/pavement noise.

Topics of Interest

This panel wishes to initiate each visit with a general discussion of current noise policy, applicable noise measuring and monitoring systems, and a summary of noise-reduction techniques. In particular, the panel is interested in how each country has developed and implemented its approach to addressing the highway noise challenge. In addition, the panel has interest in visiting the following proposed projects and test sites.

Proposed Projects and Test Sites

Projects— The panel believes these multicountry projects are relevant to the objectives of the scan. Briefings on these projects at an appropriate place would be beneficial:

SILVIA—This Belgian Road Research Center-led project has the following objectives:

1. Developing classification and conformity of production procedures of road surfaces with respect to road noise.
2. Investigating and improving structural and functional durability of low-noise pavements.
3. Developing full life-cycle cost/benefit analysis procedures for noise abatement measures.

The final product will be a European Guidance Manual on the Utilization of Low-Noise Road Surfaces. This project started in 2002 with 3-year duration. TRL (United Kingdom) or DRI (Denmark) may also be able to provide a briefing on this project.

SIRUUS—This Autostrade (Italy) -led project has the following goal:

Develop low-noise multilayer pavements with different surface and structural functions by optimizing texture, roughness, hydraulic conductivity, and sound-absorption characteristics.

This project was initiated in 1998. The final report is reportedly complete. Test sections of a “euphonic road,” which includes a concrete base containing resonators and a top layer of porous asphalt, was constructed and evaluated for this project in Italy.

Test Sections— These countries contain in-service test sections of relevant pavements documented in the literature:

Denmark

1. Double-layer porous asphalt test sections in Copenhagen built in 1999.
2. Single-layer porous asphalt test section on the Island of Zealand built in 1990 (optional).

United Kingdom

1. Exposed aggregate concrete test section on the M18 near Thorne in South Yorkshire built in 1993.
2. Exposed aggregate concrete test section on A50 in Derbyshire built in 1995.

Netherlands

1. Program overview and test sections under Silent Roads within IPG, started in 2002. The scan team is particularly interested in work associated with road surfaces cluster and assessment methods cluster.
2. Program overview and test sections associated with Roads to the Future Program.
3. Optimized exposed aggregate concrete test sections described in paper by van Leest and van Keulen for 8 th International Symposium on Concrete Roads, Istanbul, Turkey, in April 2004.
4. Double-layer porous asphalt test sections on A28 near Staphorst and Warm, and on A27 near Hilversum (Internoise 2003).

Italy

1. Euphonic road constructed under SIRUUS project on Autostrade.
2. Expanded clay aggregate asphalt pavement test section described at INTROC 1990.
3. Italgrip installations.

France

1. Double-layer porous asphalt (Epsibel).
2. Thin asphalt with rubber granules (Colsoft).
3. Lightweight aggregate in asphalt pavement (COMPOFLEX GL) test sections built in 1993 and 1995 in Puy-de-Dome and described by Tessoneau and Serfass, SCREG, at Eurasphalt and Eurobutume 1996.

Amplifying Questions

The panel is interested in discussion of the following topics with agency and research personnel, as well as technicians and contracting personnel as appropriate. Specific questions that amplify the panel’s interests in the foregoing topics include the following:

1. Policy

   • Regulatory framework
   • In general terms, explain the applicable legislative or regulatory basis or requirements for your noise policy or program.
   • How does your noise policy address the social and political impacts of roadway noise?
   • What other techniques or methods have you used to mitigate noise?
   • Do you anticipate tire pavement noise to become a regulated property?
   • What changes would you make to your current procedure based on your past experience?
   • Noise-reduction program
   • How did you introduce quiet pavements into your noise policy? Was there a trial project to work through necessary issues, such as determining each quiet pavement’s effectiveness, how to include it in a prediction model, and finally how to include it in the policy?
   • Are you required to monitor your quiet pavement to maintain a specific noise reduction?
   • Are you required to repave or clean the pavement if a specified noise reduction is not achieved or maintained?
   • Did you use a public relations campaign to market the benefits of your quiet pavements initiatives?
   • What has been the public’s reaction to the noise-reduction techniques?
   • What role does industry (including tire manufactures) play in the reduction of roadway noise?

2. Design

   Selection factors/tradeoffs

   • What criteria are used to determine if a roadway qualifies for quiet pavement surfacing?
   • How are the tradeoffs between the different pavement properties (noise, skid, smoothness, etc.) made and optimized?
   • What other tradeoffs, if any, have been made?
   • What other noise-reduction strategies are considered as alternates or options to quiet pavement construction?

   Structural design

   • Do you consider the quiet pavement layer a structural element?
   • What is a typical operational or design life of the various quiet pavement surfaces that you employ?
   • What are considered critical mix design issues?
   • What various quiet pavement technologies have been used in your country, and which do you feel are most effective and why?

   Cost impacts

   • Is there an incremental cost for quiet pavements?
   • How do you determine the upper incremental cost limit?

3. Noise Analyses

   Noise prediction

   • If you use a highway traffic noise prediction model, how is quiet pavement accounted for in the model? (e.g., spectral emission data from specific pavement types, adjustment for overall sound level, etc.)
   • Does your model consider other factors that may affect the performance of quiet pavements (e.g., environmental effects, speed of the vehicles, etc.)?

   Noise measurement

   • How do you determine the noise-reduction benefit?
   • Does your method account for multiple vehicle types and other vehicle noise sources?
   • What is the correlation of the physical pavement characteristics (i.e., macrotexture, temperature, void content, and impedance), as well as meteorological conditions, with the relevant acoustic properties of quiet pavement technologies?

   Noise monitoring

   • If it is required, how often do you monitor quiet pavement for maintenance of noise reduction?
   • Do you monitor during different seasons?
   • Does your pavement management system (PMS) track other pavement surface properties such as smoothness, friction, or splash and spray?

   Performance history

   • What has been your performance history with quiet pavement systems?
   • What performance measures do you use?
   • How much noise reduction are you achieving using quiet pavements?
   • What spectral changes are seen when introducing quiet pavements? Can you share noise spectrum data for your pavements?
   • What are the relevant acoustic properties of quiet pavement technologies? How do these properties vary with age?
   • How long is the noise benefit maintained for each pavement type?
   • Have you seen changes in the noise-reduction benefits with varying pavement temperatures or changes in noise levels with varying types of PCC joints?
   • When it rains, are the noise-reduction benefits reduced or negated?

4. Construction

   Critical factors considered before pavement construction

   • Does the type or condition of the underlying pavement or climatic condition determine the type of quiet pavement technology selected?
   • How are the projects awarded for construction (low bid, warranty, design-build, etc.)?
   • Who develops new specifications? How are they implemented?

   Quality control/quality assurance

   • During construction, who is responsible and what tests are performed to insure the desired level of noise reduction is achieved?
   • Are there penalties for failure to achieve the design noise criteria?
   • Are there laboratory tests performed that relate to field performance?

   Specialized equipment/inspection

   • Is the use of specialized construction equipment required?
   • Are special inspection techniques or training required?

5. Maintenance

   Special maintenance requirements

   • How do you maintain the effectiveness of quiet pavements?
   • Who maintains the systems?
   • Are there increased maintenance costs? How much? In what areas (materials, personnel, training, equipment, etc.)?

   Winter maintenance

   • Describe your winter maintenance approach for quiet pavements.
   • Are there safety issues associated with winter maintenance of quiet pavement systems?

   Specialized equipment

   • Is the use of specialized equipment needed for the various quiet pavement systems?
   • Who builds this equipment and who operates it?
   • Does it require enhanced technical expertise and training?
   • Is it cost effective?

6. Research

   Innovative programs

   • What new technologies and techniques have you developed?
   • How is innovation encouraged? How is risk shared?
   • What new and innovative technologies and techniques are you evaluating?
   • What capabilities do your research facilities possess?

   Promising technologies or approaches

   • Are there promising technologies or approaches that you are considering for future evaluation?
   • Are you aware of other future research that might prove promising?
   • What do you see in 5 to 10 years in the area of quiet pavements?

   Noise modeling

   • Describe your research into new noise modeling algorithms.
   • Is research into development of new and improved noise models a high priority? Why or why not?

   Metrics/human effects

   • Have you conducted any research to address the positive human effects of quiet pavement systems?