Formal Request for all Results from Noise Modeling

Modeled Noise Data results are incomplete in the Draft Environmental Assessment.

The 4(f) noise data included with the EA has some interesting features, and shows trends, but its random site distribution is problematic to larger generalizations about population impacts. We need a more thorough release of the noise data.


Subject: Request Full Results from NIRS Noise Modeling
From: Stephen Murray
Mr Robert Henry & Mr Ryan Weller,

This comment is a request for all the results from the noise data modeling that is not included within the Draft Environmental Assessment.

According to the SoCal Metroplex Noise Technical Report noise modeling used 3 different layers:

  1. Census Block Centroid Points in the General Study Area
  2.  Section 4(f) Points in the General Study Area
  3.  0.5 NM Evenly Spaced Grid Points

Only the results from the Section 4(f) Points in the General Study Area noise modeling are in the release of the Draft Environmental Assessment. These released Data Points are of noise changes at properties or resources potentially protected under Section 4(f) of the Department of Transportation Act of 1966. Important, but these data points do not adequately cover all areas of dense population or noise-sensitive areas.

Exhibit 2 of the Noise Technical Report is of the Section 4(f) Points. There are areas of significant spacing, or data gaps, between data points in the urban portions of the study area. In many areas gaps are larger than 1 nautical mile. These data gaps are evident in areas which have undergone flight path changes, and areas which fall under the Criteria for determining impact of changes in Aircraft Noise- those within the DNL 65 and higher, DNL 60 to 65, and the DNL 45 to 60 exposure levels. These gaps represent areas of significant population that are lacking evaluative data.

The noise data may have been omitted because the level of noise exposure change was determined to not have reached the threshold of a significant impact, and I know there were discussions of how such a large data set could be released.

With more than 1,242,614 flight tracks modeled, the NIRS models performed for the Draft Environmental Assessment are unprecedented in scope and detail. These can be an important resource to inform about airspace use and the positive and negative effects of the proposed changes on noise-sensitive areas in Southern California.

I have two requests in regard to this very important data:

  1. I would like the noise modeling data from the Census Block Centroid Points released in a similar structured format as the 4(f) data with at least: Census block name, centroid coordinates, existing 2013 dB DNL, and the dB DNL of no action and proposed action for 2015 and 2020. Releasing this data set will help to fill in some of the data gaps in the noise-sensitive urban areas by anchoring noise levels to predefined population clusters. Understandably this is the largest data set but it allows connection of noise effects to population groups, an area in which the EA has not demonstrated.
  2. The data from 0.5 NM Evenly Spaced Grid Points promises to be very difficult for a member of the general public to understand or interpret if released in a table format. If the 0.5 NM Evenly Spaced Grid Points data set can be released in a data format that will readily allow scientists and geographers to create maps and tables, I would like to see this data released. A similarly structured format of Point ID(if used), coordinates, existing 2013 dB DNL, and the dB DNL of no action and proposed action for 2015 and 2020.

The Draft EA helps to demonstrate that there will be no significant noise impacts from the new procedures. I believe that residents and elected officials are additionally anxious with how the noise will change. Disclosing data that can be used to inform these concerns will help our elected officials and the general public further understand and manage expectations of the noise impacts to specific neighborhoods.

By the FAA supplying additional clarifying information, I hope that the communities can better engage and understand the draft Environmental Assessment. This will allow the FAA to receive additional valuable information that will allow refinements to procedure design prior to implementation. This in turn will help the FAA achieve a higher level of success with the projects implementation.

Thank you for your consideration to this request.

Stephen Murray