Traffic noise impacts occur when predicted noise levels approach or exceed Federal Highway Administration (FHWA) noise abatement criteria (NAC). Noise measurements were taken at 70 locations representing 128 residences, two hotels, one park, the JBLM Fire Department, the JBLM 911 Call Center, the Memorial Arboretum and Historic Gas Station, and several commercial structures. The study area was divided into three areas: The Exit 119 area, the Greenwood neighborhood, and the Davis Hill neighborhood. These areas, and the noise measurement locations, are shown in [figure].
How does WSDOT decide if a noise wall gets built?
At locations where noise impacts are forecast to occur, in general, WSDOT determines if a noise wall is feasible by evaluating whether it is physically constructible and will achieve a meaningful reduction in noise levels for affected receivers. If a wall is feasible to construct, WSDOT then assesses if it is reasonable by considering factors such as cost-effectiveness and the expected level of noise reduction for nearby homes, businesses or other features such as parks or hospitals.
To learn more about the process WSDOT uses to determine whether an area qualifies for a new noise wall, visit the road noise and noise walls page.
Currently, 28 residences on JBLM exceed FHWA Noise Abatement Criteria (NAC). Once the project is constructed, 35 residences would exceed the NAC in the PM peak hour, an increase of seven residential units compared to the No Build Condition. Five of the new impacts are in the JBLM Greenwood neighborhood and two are in the JBLM Davis Hill neighborhood.
Proposed New Noise Walls
33 of the impacted residences can be mitigated through construction of noise walls, leaving two units in Davis Hill unavoidably impacted. Proposed noise walls would reduce noise exposure for most of the homes that exceed the NAC. The proposed wall locations are shown in [figure(s)].
Greenwood Noise Wall
- Located within WSDOT right of way
- Length: 1,425 feet
- Height:12 to 16 feet tall
- Average noise reduction: 7 dB at the homes closest to the wall
- No noise receivers in the Greenwood neighborhood would exceed noise threshold after construction of the wall
Davis Hill Noise Wall
- Located on JBLM property at the top of Davis Hill
- Length: 1,100 feet
- Height: 4 to 8 feet tall
- Average noise reduction: 9 dB at the homes closest to the wall
- Noise impacts would be reduced in seven duplex units, one unit would remain above noise threshold
For More Information
To read more about the study approach, existing conditions, and effects on noise, please see Section 3.5 of the Supplemental Environmental Assessment.