Highway traffic noise is comprised of sound from many vehicle types and many sources for each vehicle. One commonality among vehicle types is that the tire/pavement noise source substantially contributes to the overall highway traffic noise levels at highway speeds. Tire/pavement interaction noise studies have shown that there are measureable noise level differences among roadway pavement types. Such studies include international data [Sandberg 2002] [Gibbs 2005] and data from states and research centers throughout the U.S., such as Arizona [Scofield 2003][ADOT 2006][ADOT QPPP], California [Caltrans 2005][Caltrans 2010], Colorado [Hanson 2006][Rasmussen 2009], Florida [Wayson 2009], Kansas [Brennan 2006], New Jersey [Bennet 2004], Ohio [ODOT 2005], Texas [Trevino 2009-1][Trevino 2009-2], Virginia [McGhee 2009][McGhee 2010], Washington [Sexton 2010], National Center for Asphalt Technology [Fortier Smit 2008], National Concrete Pavement Technology Center [Rasmussen 2008], and MnROAD [Izevbekhai 2007]. (Note: A synthesis of these references can be found in Sohaney 2011.)
Because there are still many questions to be answered concerning noise-related pavement benefits (e.g., amount and longevity of community benefit, etc.) for a large array of specific pavement types, the U.S. Federal Highway Administration (FHWA) is keeping with its long-standing requirement to use a national average pavement type for future highway noise predictions. As pavement noise studies progress, Federal noise policy is being examined for potential changes. The FHWA Traffic Noise Modelâ (FHWA TNM) [Anderson 1998][Menge 1998] is directly linked to 23 Code of Federal Regulations, Part 772, and it must be used for noise predictions on highway projects receiving Federal aid. The FHWA TNM Pavement Effects Implementation Study was initiated to help determine how to incorporate a broad range of pavement effects in the FHWA TNM.1 This study is being conducted by the U.S. Department of Transportation / Volpe National Transportation Systems Center.
Three possible options were considered for implementing pavement effects in the FHWA TNM:
Implementation Option 1): integrating new data into the FHWA TNM vehicle noise database (Reference Energy Mean Emission Levels or REMELs, [Fleming 1995]) for specific pavement types and also adjusting the roadway effective flow resistivity (EFR, a measure of sound absorption);
Implementation Option 2): adjusting the existing tire/pavement source level in the FHWA TNM and also adjusting the roadway EFR for specific pavement types; and
Implementation Option 3): applying a pavement type offset adjustment value to the predicted sound levels (post FHWA TNM calculations).
This report describes three different investigations:
In each section, data collection, data analysis, implementation methodology, and validity of the methodology are described. Section 5 of this report includes conclusions regarding each of the investigations, as well as recommendations for each implementation option listed in Section 1.1.