Roadway Impact Assessment of Highway Construction
Client: Vermont Agency of Transportation
Challenge
The Vermont Agency of Transportation (VTrans) is planning to expand the Circumferential Highway (VT 289), a roughly 15-mile stretch of road in northern Chittenden County. A roadway noise study was required for the project’s revised Environmental Assessment.
Initiative
VTrans retained RSG to assess potential related roadway noise impacts for a number of locations near the alignment of a proposed section of the highway. For this project we:
- Installed sound level monitoring equipment to measure existing ambient sound levels
- Scheduled sound level monitoring in conjunction with a VTrans traffic count, which measured total traffic volume and vehicle type, for an existing segment of VT 289
- Developed a computer-based traffic noise prediction model of VT 289 and nearby roadways, including Interstate 89, using the Federal Highway Administration’s Traffic Noise Model (TNM)
- Validated TNM results with measured traffic and sound level data
- Reviewed TNM results according to state and federal guidelines to determine whether noise impacts would occur from the proposed project
Results
Our monitoring results, combined with field observations, indicated that ambient sound levels in the project area result largely from roadway noise from Interstate 89. Model-predicted results indicated that Noise Abatement Criteria will not be exceeded and that that in none of the scenarios would noise levels increase substantially. This is due, in part, to sound attenuation by two existing berms, which were built in anticipation of the project. Study results were incorporated in the updated environmental assessment for the proposed project.
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