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Traffic Noise Abatement Policy and Manual Updates

Gannett Fleming helps NCDOT rethink its noise policies to ensure compliance and streamline procedures.
  • Construction of new express lanes along I-77 in North Carolina showing traffic moving through work zones with construction barriers - Gannett Fleming.

    NCDOT’s traffic noise policies help to mitigate the impact of highway projects on local communities. (Photo by Sugar Creek Construction, lead contractor on the I-77 Express Lanes project near Charlotte, North Carolina).

  • Instrument for measuring sound levels sits on a tripod near a rural highway - Gannett Fleming.

    Engineers use sound level meters to measure noise volumes near residential properties.

Client
North Carolina Department of Transportation
Location
Raleigh, North Carolina
Our Role
Noise Policy and Guidance Manual Review and Recommendations.
Data
Completed:
2016
Duration:
2 years
Outcomes
  • Updated traffic noise abatement policy reflects FHWA requirements and best practices
  • Improved traffic noise measurement and validation procedures increase accuracy
  • Revised NCDOT noise abatement manuals are consistent with FHWA regulations
  • Developed the first draft highway noise Programmatic Agreement in the U.S.
  • Created screening methods to exempt low-volume roadways from noise analysis. 

The North Carolina Department of Transportation (NCDOT) maintains approximately 80,000 miles of roadways and 18,000 bridges and culverts across its state. NCDOT’s Traffic Noise Abatement Policy and Traffic Noise Analysis and Abatement Manual provide guidelines for protecting communities adversely affected by traffic noise from proposed state and federal highway projects. NCDOT guidelines did not reflect current Federal Highway Administration (FHWA) noise regulations and needed to be updated.

NCDOT turned to Gannett Fleming for help in reviewing its noise abatement policies and manuals for compliance with current and future federal regulations. Our acoustical experts brought knowledge of best practices from across the U.S. from their work developing noise policies for the Pennsylvania Department of Transportation, the New Jersey Turnpike, and other state highway agencies. 

What We Did

Gannett Fleming’s staff identified potential issues with NCDOT’s noise policies and procedures and recommended changes to improve the noise abatement process and bring both documents in line with FHWA guidelines. Their comprehensive review incorporated the latest information from both the FHWA Traffic Noise Model (TNM) and the National Cooperative Highway Research Program (NCHRP) supplemental guidance on traffic noise modeling. Our experts also evaluated NCDOT noise modeling requirements and provided recommendations regarding noise measurement and validation procedures.

The most significant outcome of this review process was the development of the first draft highway noise programmatic agreement between the FHWA and a state transportation agency. Gannett Fleming collaborated with NCDOT and FHWA to propose changes that would allow NCDOT to screen roads by traffic volume, then exempt those below a certain volume from noise analysis. This new procedure will save the state both time and money by eliminating unnecessary noise studies. In order to develop the draft agreement, Gannett Fleming identified traffic volumes, vehicle mixes, speed thresholds, and roadway characteristics that would not be expected to result in traffic noise impacts from Type I projects. FHWA expressed support for the draft agreement which, once approved, could serve as a model for other states’ highway noise policies. 

Key Features

  • Revised the NCDOT noise policy and abatement manual for consistent terminology
  • Ensured that state highway noise policies comply with FHWA regulations
  • Incorporated latest research and best practices into policy development
  • Developed a traffic noise screening methodology applicable to other state highway agencies
  • Drafted a programmatic agreement that will save time and money by eliminating unnecessary noise studies on roads with low traffic volumes.

Similar Projects: Acoustics, Federal: Environmental, Transportation: Highways, Environmental Management & Remediation: NEPA Compliance & Documentation, Transportation: Planning, Federal: Transportation