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Traffic Noise Impact Analyses Using a Screening
Methodology: Oregon DOT Experiences
• Presented by: Carole Newvine/Noise Specialist
Oregon Department of Transportation
• Presented at: Transportation Research Board ADC40 Transportation-Related Noise and Vibration 2013 Summer Meeting - Santa Fe New Mexico
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Outline
• OR DOT previous screening methodology
• New screening methodology
• Project experiences using screening – Local Gov’t – suburban setting
– Rural setting
– Protected forest land
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Previous Screening Methodology
prior to 23 CFR 772 update (2010)
Assumptions Receptor Distance: 15 meters from roadway CL Site Characteristics: Hard site, infinite flat roadway, no shielding Vehicle Speeds: 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 km/hr Traffic Characteristics: Peak Hour Traffic Volume (PHT) = 21% of ADT volume Truck Volume = 30% of PHT Volume (27% Heavy Trucks, 3% Medium Trucks) Study Year: 2015
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Previous Screening Methodology
prior to 23 CFR 772 update (2010)
Year Speed ADT 2015 30 km/hr 950
40 km/hr 600 50 km/hr 450 60 km/hr 300 70 km/hr 250 80 km/hr 200 90 km/hr 150 100 km/hr 140
110 km/hr 130 120 km/hr 110
Traffic volumes, speeds below would result in predicted noise levels of Leq 64 dBA at 15 meters (50 ft) from centerline.
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2013 Problem/Solution
• Oregon’s Type I projects in rural areas – project delivery impacted
• No provisions in Federal rule for programmatic streamlining
• Some states already had approval for screening methodologies
- Idaho
- Washington State
- Virginia
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ODOT Screening Methodology for Traffic Noise Impacts – March 2013
Applicability:
Type I projects where noise impacts are not anticipated or when there are impacts but no feasible abatement
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ODOT Screening Methodology – Highlights:
• Oregon’s screening methodology – mirrors WA, ID, VA methods
• TNM to estimate existing, design year traffic noise levels at selected distances from the roadway centerline – out to 1500 ft.
• Conservative results: assumes worst case conditions not actual roadway design or topography
• Technical report required
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ODOT Screening Methodology – Highlights Continued:
• Validation of the straight line model is not required
• Traffic data, vehicle speeds, actual receptor distances from the roadway for Build condition for NAC determination
• Compare Existing to Build to determine substantial increase impacts
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Complex Modeling Straight-line Modeling
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ODOT Screening Methodology Post Modeling
• If abatement appears feasible - detailed analysis required
• No abatement feasible (e.g., driveway access), a detailed noise analysis (full TNM modeling) is not required
• Noise monitoring may be required
• 23 CFR 772 requirements must still be met
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ODOT Screening Analysis for Traffic Noise Impacts – March 2013
Advantages: – Can be done in-house – Saves budget – Can be performed earlier in the project development cycle -
only limited design information needed
Disadvantages: – Limited use – conservative results – Can’t be used for analysis of alternatives – Inappropriate use
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Local Gov’t – Suburban Setting Freeman Road: Central Point
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Local Gov’t – Suburban Setting Freeman Road: Central Point
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Local Gov’t – Suburban Setting Freeman Road: Central Point
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Rural Setting
OR86: Baker County
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Rural Setting
OR86: Baker County
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Rural Setting
OR86: Baker County
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Protected Forest Land US26: Mt Hood Safety Project
Protected Forest Land US26: Mt Hood Safety Project
Critical Viewpoint:
Laurel Hill. Existing Condition
Laurel Hill. Proposed Condition
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Protected Forest Land US26: Mt Hood Safety Project
Critical Viewpoint:
Mirror Lake. Existing Condition
Mirror Lake. Proposed Condition
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Protected Forest Land US26: Mt Hood Safety Project
Mirror Lake Trailhead (continued)
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Protected Forest Land US26: Mt Hood Safety Project
Critical Viewpoint: The Pioneer Bridle Trail at MP 51.30
The Pioneer Bridle Trail at MP 50.90
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Protected Forest Land US26: Mt Hood Safety Project
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Critical Viewpoint: Map Curve.
Suburban setting: Impacts with accessibility issues Rural setting: No impacts
USFS lands, 4(f): Impacts; access issues, Federal and County viewshed restrictions; exceeds cost criteria
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Summary: Type I Projects – Screening Methodology
Contact Information
Carole Newvine/ Noise Program Coordinator 503-986-3447 carole.newvine@odot.state.or.us
Natalie Liljenwall/Air and Noise Engineer 503-986-3456 natalie.liljenwall@odot.state.or.us
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