tahoemonitoring.org

  • Increase font size
  • Default font size
  • Decrease font size
Home People Soundscape

Industrial Areas & US Highway 50

Status and Trend

Interpretation and Commentary

Industrial

Status: At or Somewhat Better Than Target
Trend: Little or No Change
Confidence: Low

US Highway 50

Status: At or Somewhat Better Than Target
Trend: Rapid Improvement
Confidence: Low

Click to interpret these icons
  • Relevance - This indicator measures 24-hour noise levels in the Industrial land use category and the US Highway 50 transportation corridor in the Lake Tahoe Basin.Noise by definition, is “unwanted sound,” and is therefore a subjective reaction to acoustical energy or sound levels. Due to the rural nature of the communities and the pristine natural areas in the Lake Tahoe Basin, noise management is an integral part of land use planning and environmental improvement processes at Lake Tahoe. Visitors and residents have expressed concerns about the decline in serenity of their community and their enjoyment of the outdoors due to excessive noise from sources such as on-highway vehicles, off-highway vehicles, over-snow vehicles, watercraft and aircraft(TRPA 2007c). In addition to existing federal, state, and local noise control regulations, an effort to address these noise level impacts, the Tahoe Regional Planning Agency adopted 24-hour noise Threshold Standards, or Community Noise Equivalent Levels (CNEL), for all land use categories and plan areas of the Basin.
  • Adopted Standards  - For the Industrial land use category and US Highway 50 transportation corridor, noise levels shall not exceed a CNEL of 65 dBA.
  • Indicator - A-weighted Decibel (dBA). The A-weighted decibel measurement is used in evaluating the effects of environmental and industrial noise effects on human health.
  • StatusIndustrial – The Industrial land use category has reported “in-attainment” status since 1991 (Engineering Dynamics 1991; TRPA 1996, 2001). In 2011, an annual mean CNEL value of 53 dBA was measured, ranging from 52 to 58 dBA (TRPA 2011d). A status of “at or somewhat better than target” was determined because it was 11% better than the adopted standard.
  • Status   US Highway 50 – The US Highway 50 transportation corridor reported “non-attainment” for one sampling period (2001) in a total of 2 sampling periods (TRPA 2001). In 2011, an annual mean CNEL value of 61 dBA (range 58 to 65 dBA) for the US Highway 50 transportation corridor was measured (TRPA 2011d). A status of “at or somewhat better than target” was determined because it met the adopted Threshold Standard (neither worse nor better).

Click here for more information...

  • Trend Industrial – The change in CNEL for the Industrial land use category between 1991 and 2011 was +0.04 dBA/year or +0.3% indicating a trend determination of “little or no change.”
  • Trend -  US Highway 50 – Since 1991,the change in CNEL for the US Highway 50 transportation corridor was -0.5% dBA/year or -3.8% indicating a trend determination of “rapid improvement.”

Confidence

  • Status – Even though 1) noise monitoring equipment was calibrated according to manufacturers’ specifications, 2) sampled land use units and locations within each land use category were randomly selected to improve inferences about the population of these land uses, and 3) additional sampling effort was deployed in 2011, a documented and peer-reviewed protocol for CNEL monitoring does not exist. Consequently, the confidence in the status was determined to be “moderate,” because of the spatial and temporal characterization of CNEL across these land use types.
  • Trend – The confidence in the trend for the Industrial land use category is “low” for the analysis of 4 data points with a confidence of 15% and a P value of 0.85. Trend confidence in the trend for the US Highway 50 transportation corridor is automatically assigned “low” due to the lack of statistical trend analysis (only 2 data points).
  • Overall Confidence - The overall confidence for the Industrial land use category is “low” because there is “moderate” confidence in status and “low” confidence in trend. The overall confidence for the US Highway 50 transportation corridor is “low” because there is “moderate” confidence in status and “low” confidence in trend.
  • Human and Environmental Drivers - Anthropogenic noise levels affecting these land use categories and transportation corridor are primarily generated from vehicles, roadway traffic, aircraft and recreational activity(TRPA 2011c).Othersecondary anthropogenic noise influences include noise attributed to road construction and ambient Basin noise(TRPA 2011c). Natural events such as thunderstorms and wind influence noise levels as environmental drivers(TRPA 2011c).
  • Monitoring Approach – There is currently no established peer-reviewed monitoring plan or protocol for monitoring and evaluating the CNEL indicator. Historical monitoring consisted of gathering a single 24-hour sample per measured plan area. Threshold Standard attainment status was based on a single sample representing a land use type. In contrast to historic monitoring efforts, a more comprehensive CNEL monitoring effort was implemented in 2011. The 2011 monitoring approach was based on recommendations provided by a noise expert (Brown-Buntin Associates, Inc.), and included randomization of land use unit sampling within land use categories, and a replicated and intensified sampling effort that spanned multiple 24-hour periods to improve the characterization of variation in CNEL.
  • Monitoring Partners – Monitoring was conducted by TRPA with land access granted by U.S. Forest Service.

Links

 
  • Monitoring Plan
  • Conceptual Model

Map

click map for larger image

A map of the Industrial land use category areas and US Highway 50 transportation corridor, with monitoring locations (CNEL 65 dBA).

Trend Charts

You need to upgrade your Flash Player
 
High and low single day CNEL values (bar endpoints), with annual mean CNEL in land use categories and transportation corridors having a Threshold Standard of CNEL 65 dBA from 1991 to 2011. Source:  TRPA noise monitoring data, Brown and Buntin Associates, Inc., Engineering Dynamics, Inc.

Additional Info

References

Additional Information

Last Updated on Wednesday, 19 September 2012 14:15