U.S. Department of Transportation
Federal Highway Administration
James M. Shrouds
Director, Office of Natural and Human Environment
Federal Lands Highway Division Engineers
Date: January 19, 2005
Reply to: HEPN-20
This memorandum provides guidance to a State DOT(s) that wants to develop a Quiet Pavement Pilot Program (QPPP) or conduct tire/pavement noise research. It specifically provides information on the QPPP implemented by the Arizona Department of Transportation (ADOT). Please note that the selection of pavement type and texture is based on engineering and economic analysis, specifically including safety and durability considerations. Pavement safety and durability should never be jeopardized to obtain noise reduction.
The FHWA noise program policy related to tire/pavement noise, contained on page 31 of "Highway Traffic Noise Analysis and Abatement: Policy and Guidance" reads as follows:
"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.
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."
The FHWA policy restricts making adjustments for pavement type in the prediction of highway traffic noise levels and using specific pavement types or surface textures as noise abatement measures.
As a result of input from the general public, as well as results from studies conducted during the 1990's, ADOT asked the FHWA for approval to implement a QPPP, specifically to use asphalt rubber friction courses on selected freeway segments in the Phoenix area to reduce noise. The FHWA approved ADOT's QPPP in June 2003. Based on similar public concerns and tire/pavement noise studies, the California Department of Transportation has indicated a desire to develop a proposal for a QPPP in California.
The QPPP's are intended to demonstrate the effectiveness of quiet pavement strategies and to evaluate any changes in their noise mitigation properties over time. Current knowledge on changes over time is extremely limited. Thus, the programs will collect data and information for at least a 5-10 year period, after which the FHWA will determine if policy changes to a State DOT(s) noise program are warranted.
The QPPP's will accomplish the following:
Account for documented noise reduction benefits of pavement types by adjusting predicted (modeled) highway traffic noise levels in project noise analyses (this may either reduce the number of identified traffic noise impacts or reduce the height of noise barriers that are required to mitigate identified traffic noise impacts);
Include post-construction monitoring for the projects to collect acoustic, texture, and frictional characteristics (monitoring will be performed for at least 5-10 years);
Document the general public's reaction to the noise reduction capabilities of specific pavement types; and
Include commitments to take appropriate actions to provide required noise reduction into perpetuity.
The development of a QPPP is strictly voluntary and should not preclude the use of any "quieter pavement" technology. To account for variability in pavement designs and materials, as well as differing climatic conditions, a QPPP should be State-specific. However, if a group of State DOTs would like to jointly enter into a QPPP, they may do so if they collectively agree on the same pavement type(s), design(s) and materials. The State DOTs should also experience the same climatic conditions. The program should include a Program Plan and a Data Acquisition Plan, which should be reviewed and approved by the respective FHWA Division Office with the concurrence of the Office of Natural and Human Environment (HEPN).
The Program Plan will be specific to that State DOT(s). At a minimum, a State DOT(s) should address the nine items outlined in the attached Arizona DOT Program Plan. The Data Acquisition Plan should contain requirements to monitor noise characteristics, as well as safety and durability factors, measured over time [e.g., vehicle incident data, wayside acoustical data, porosity, frictional characteristics, skid number, impedance, etc.). The attached Sample Data Acquisition Plan should be used as a proto-type for data collection; however, a State DOT's QPPP may add items to adequately document the safety, durability, and noise requirements of their program. A State DOT(s) that adopts at a minimum the nine items in the Arizona DOT Program Plan and the Sample Data Acquisition Plan will obtain concurrence from FHWA HEPN.
For any project in a QPPP, a State DOT(s) is allowed to make adjustments for pavement type in the prediction of highway traffic noise levels and/or use specific pavement types or surface textures as noise abatement measures. However, a commitment must also be made to maintain in perpetuity any noise reduction attributed to the pavement type or surface texture.
A State DOT(s) may also elect to conduct "quiet pavement" research. Once completed, this research would help substantiate a possible future policy change in its program to allow the use of a pavement adjustment factor in traffic noise predictions and the use of pavement types or surface textures as noise abatement measures. To conduct "quiet pavement" research, a State DOT(s) should develop a Quiet Pavement Research Plan that (1) outlines its intended purpose, (2) details all data acquisition, and (3) contains periodic reporting requirements. The Research Plan should be reviewed and approved by the respective FHWA division office, with the concurrence of HEPN. The attached Sample Data Acquisition Plan should be used as guidance for data acquisition. Noise data must be gathered to document the noise levels in residents' backyards (wayside acoustical data). The research should include, for each applicable pavement type, a minimum of four studies that substantiate the policy change being considered. To account for variations in pavement design, construction, maintenance, and materials, these studies should (1) be in different locations within the State; (2) collect noise characteristics and safety and durability data for at least 5-10 years (or longer, based on the pavement life); and (3) involve different construction contractors.
The 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 at a national level. This also can help to determine any correlation between pavement characteristics (e.g., texture or skid resistance), safety, durability, and noise reduction. The two major differences between a QPPP and "quiet pavement" research are discussed below.
First, a State DOT(s) entering into the QPPP has already submitted acceptable documentation on a specific pavement type's noise reduction and safety capabilities over time. With this approved documentation, the State DOT(s) may make adjustments for (1) pavement type in the prediction of highway traffic noise levels; and (2) the use of specific pavement types or surface textures as noise abatement measures. These adjustments must be based on existing documentation. A State DOT(s) conducting "quiet pavement" research may not make these adjustments until acceptable documentation on a specific pavement type's noise reduction and safety capabilities over time is submitted and approved. This determination will not be made until the "quiet pavement" research is completed.
Second, a State DOT(s) implementing a QPPP must make a commitment to monitor noise levels and take appropriate actions, if the noise reduction benefits do not last in perpetuity. A State DOT(s) conducting "quiet pavement" research does not need to make any commitment regarding the noise reduction benefits of the pavement, since no change in program policy, i.e., adjustments for pavement can occur until the research is complete.
The Data Acquisition Plan for any QPPP or "quiet pavement" research should, as a minimum, contain what is presented in the attached Sample Data Acquisition Plan. If any pavement that is constructed in the QPPP and/or "quiet pavement" research fails to meet structural requirements to the extent that road users' safety is compromised, the State DOT(s) shall immediately take action to achieve acceptable safety levels by (1) repaving with an adjusted pavement mix, or (2) repaving with a documented safe pavement type or surface. The determination of the appropriate action shall be with the concurrence of FHWA.
No special or separate funding is available for the development of a QPPP or "quiet pavement" research. However, construction of a quiet pavement may be funded with any appropriate category of FA construction funds. The evaluation of a QPPP or "quiet pavement" research may be funded either as part of the construction project or as a separate project with NHS or STP, which can be used for research, development and technology transfer, or with SPR funds. The SPR funds may not be used for construction of the pavement.
In summary, FHWA policy does not allow the use of pavement type or surface texture as a noise abatement measure. If policy change is to occur, results of the QPPP and/or additional research must demonstrate the safety and durability of each "quiet pavement," as well as its noise reduction capability. The safety and noise reduction of the pavement must last in perpetuity. In the short term, any policy change will be State specific, i.e., the change will only apply to a given State DOT(s) for a specified pavement type and/or texture. If warranted, changes in national policy may be considered in the future. The FHWA will disseminate information regarding Quiet Pavement Pilot Programs and Tire/Pavement Noise Research as they are developed and as deemed appropriate.
Questions and comments on the QPPP or "Quiet Pavement" research should be directed to Mark Ferroni (Mark.Ferroni@fhwa.dot.gov) at (202) 366-3233 or Chris Corbisier (Chris.Corbisier@fhwa.dot.gov) at (202) 366-1473, respectively.
cc: Directors of Field Services