Presentation to:2006 Transportation Research Board

Noise & Vibration ConferenceWilliamsburg, VA

Supplemental Tools for Environmental Noise Analysis

Roger OdegardWyle Research & Consulting

Acoustics--Aviation Services--GIS

July 10, 2006

Overview

U.S. Federal Noise Policy

Traditional DNL Analysis

Supplemental Noise Analysis – Review of Metrics and Tools

Supplemental Noise Analysis – Next Steps and Future Research

U.S. Federal Noise Policy

Day-Night Average Sound Level (DNL) &Community Noise Equivalent Level (CNEL):

• U.S. Federal Agencies adopted DNL/CNEL as the primary metrics to describe noise exposure– Ref: EPA Levels Document, FICUN, FICON, FICAN

• Single-value metrics that defines the long-term, cumulative noise exposure.

• Defines significant threshold values for NEPA, Part 150, AICUZ, and similar studies.

• Applicable instrument for noise control around airports– Compatible land-use planning– Zoning restrictions– Sound insulation/acquisition/relocation programs (FAA)

Traditional DNL Analysis

Recurring Issues:

• Reliance on DNL to communicate noise exposure– DNL is often hard to understand; not in lay terms– DNL alone does not fully convey a person’s everyday experience– Applies to community and non-technical decision makers

• DNL 65 dB Significance Threshold (DoD/FAA)– Historical Goal: maintain balance between the effects on people and

the cost/feasibility of reducing the effects– Not a “line-in-the-sand” regulation, only a guideline for long-term

planning– FAA defines this value as the threshold for mitigation (i.e., sound

insulation and acquisition/relocation) funding– Unintended message that noise issues beyond 65 dB DNL do not need

to be addressed

• Overall result is a mistrust in the validity and use of DNL

Traditional DNL Analysis

• Major issues not fully addressed by DNL– The use of layman’s terminology

– Number, frequency, sound level, duration, and time-of-day for events

– Applicability to Rural vs. Urban/suburban environments

– Activity interference (speech/sleep) and quality-of-life issues

• Supplemental noise analysis is often needed to help the public and the decision makers better understand the complex nature of the overall noise environment.

Supplemental Noise Analysis – Metrics and Tools

• Broad term for analysis used to expand upon and support the traditional DNL analysis.– DNL remains the metric of choice for land-use

compatibility and evaluating noise impacts (NEPA, Part 150, AICUZ)

– Goal: breakout the component parts of DNL

– Endorsed by FICAN in February 2002 position paper

• Includes graphics, maps, tables, technical analysis, and supplemental noise metrics.

Supplemental Noise Analysis

Examples:• Flight Density Maps• Noise Exposure Maps – Visualization Tools• Time-Above a Specified Sound Level (TA)• Number-of-events Above a Specified Sound Level

(NA)

Flight Frequency Maps

• Depicts modeled aircraft over-flight frequency and distribution

• Departure and arrival corridors better understood, in comparison to flight tracks

• Can focus in on special categories such as aircraft type, time of day, operation type, or air carrier

DNL Noise Exposure MapsGradual Color Shading Technique

• DNL noise contours with a gradual color shading– Noise exposure shown

beyond 65 dB DNL without requiring outer noise contours

– Public response very positive

• Aerial photograph or base map overlays

• Helps describe the long-term “flow” of aircraft noise in a snapshot.

Time-Above a Specified Sound Level (TA)

• Definition - total time (usually minutes) that aircraft noise levels exceed a defined sound level threshold

• Uses - contour bands or tables at selected grid points.

• No defined Federal agency threshold levels

Number-of-Events Above a Specified Sound Level (NA)

• Definition - total number of aircraft events that exceed a defined sound level threshold over a desired time period.

• Sound level threshold can be defined in terms of Lmax or SEL.

• NA metric can be displayed as contour bands or tables at selected grid points.

• No defined federal agency threshold level.

Grid Point AnalysisThe Components of DNL

Condition

Average

Annual Day (24

Hours)

Number of Events Above (NA) Specified Sound LevelsTime Above (TA) Specified

Sound Levels

Average Annual Day (24 Hours) Total

NA 50+

SEL (ops)

Nighttime (10:00 pm - 7:00 am)

Average Annual Day (24 hours)

DNL

NA 50-

55SEL (ops)

NA 55-

60SEL (ops)

NA 60-

65SEL (ops)

NA 65-

70SEL (ops)

NA 70-

75SEL (ops)

NA 75-

80SEL (ops)

NA 80+SEL (ops)

NA 50

SEL (ops)

TA 50

(min)

TA 55 (min)

TA 60

(min)

TA 65 (min)

Existing Condition

29.3 29 15 4 8 0 0 0 56 2 2 0 0 0

Alternative 6

29.6 31 15 4 8 0 0 0 58 3 2 <1 0 0

Change 0.3 1 <1 <1 0 0 0 0 2 <1 <1 <1 0 0

Existing Condition

41.4 67 90 46 25 9 2 0 238 23 17 4 1 <1

Alternative 6

41.4 68 90 46 25 9 2 0 239 23 17 5 1 <1

Change 0.0 1 <1 0 0 0 0 0 <1 <1 <1 <1 0 0

Existing Condition

39.7 38 49 45 17 7 1 0 158 13 12 3 <1 0

Alternative 6

39.7 40 50 45 17 7 1 0 160 14 12 3 <1 0

Change 0.0 2 <1 <1 0 0 0 0 3 1 0 <1 0 0

Supplemental Noise AnalysisNext Steps and Future Research

• Using supplemental analysis tools to extract out information within DNL is useful:– Communicates noise exposure in everyday terms

– Decision makers are better informed of potential effects

• Does not disclose the long-term adverse impacts on:– Speech interference

– Sleep disturbance

– Other health and quality-of-life issues

• What thresholds are appropriate for various circumstances?

DoD Supplemental Metrics Guidelines

• Engage FICAN and JPDO/Environmental IPT to review Federal policy regarding supplemental metrics

• Literature review of research findings– Noise-Induced Hearing Impairment

– Interference with Speech Communication

– Sleep Disturbance

– Among others

• Review of Legal Precedence – Studies Relying on Supplemental Analysis

Supplemental Tools for Environmental Noise Analysis

Roger OdegardWyle Research & Consulting

Acoustics--Aviation Services--GIS

Arlington, VA – El Segundo, CAwylelabs.com