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SR 510/Yelm Loop – New alignment phase 2 online open house – Road noise

As part of the Supplemental Environmental Assessment (SEA), WSDOT examined traffic noise levels and identified where impacts would result and proposed strategies to mitigate those impacts at qualifying locations.

How did WSDOT forecast noise levels and impacts?

WSDOT conducted a Noise Impact and Mitigation Analysis in the project area to predict peak hour noise levels associated with the completion of the SR 510/Yelm Loop. WSDOT staff installed noise receivers at 35 locations adjacent to the corridor to measure existing noise. Across those 35 locations, the noise levels ranged from 50-64 average decibels (dBA), or from quieter than a conversation heard from 3 feet away (typically 50 dBA) to slightly louder than a typical office environment (60 dBA).

A project noise analysis includes the following three basic steps:

  1. Are there receivers where noise levels are forecasted to meet the criteria for being impacted?
  2. For receivers that are forecasted to be impacted, is abatement feasible?
  3. For impacted receivers where abatement is feasible, would it meet cost reasonability criteria?

Details about these steps can be found in the WSDOT Traffic Noise Policy (pdf 743 kb)

Who qualifies for noise mitigation?

To be considered eligible for noise mitigation as part of this project, a property must have been approved for development before February 1, 2000. This is when WSDOT’s proposed highway alignment for the SR 510/Yelm Loop officially became part of the public record. For properties developed after that date, private developments and local communities are responsible to mitigate for any expected noise impacts.

The potential increase in noise level is also an important consideration. If a WSDOT project will increase noise levels at a noise mitigation eligible property more than 10dBA above current levels, or beyond 66dBA, that property would be defined as “impacted” and could qualify for mitigation.

What did the analysis find?

Twenty-two properties along the 510/Yelm Loop alignment were predicted to experience a more than 10dBA increase in noise due to traffic on the proposed road. Four of those are predicted to experience noise levels at more than 66dBA.

Is noise mitigation a part of this project?

View Royale neighborhood (built prior to February 1, 2000)

  • The View Royale neighborhood is eligible for a 1,291 foot-long, 12-foot high noise wall on the south side of the right of way between Crystal Springs and Rhoton Road.

Mountain Sunrise (permitted in 2005)

  • Ineligible for noise mitigation
  • Noise impacts will not exceed 10dBA additional noise or 66dBA overall

Mountain Shadow (permitted in 2007)

  • Ineligible for noise mitigation
  • Noise impacts will not exceed 10dBA additional noise or 66dBA overall

Canal Estates (permitted in 2001)

  • Ineligible for noise mitigation
  • Noise impacts will not exceed 10dBA additional noise or 66dBA overall

Longmire Park (permitted in 2001)

  • Ineligible for noise mitigation
  • Noise impacts will not exceed 10dBA additional noise or 66dBA overall
This image shows the proposed noise wall location along the View Royale neighborhood between Crystal Springs Road and Rhoton Road.