SMOOTHED ACOUSTIC PROFILES (Revised Methodologies and Positive Results of Smoothed Noise Wall Profile Assessment)

Transcription

1 SMOOTHED ACOUSTIC PROFILES (Revised Methodologies and Positive Results of Smoothed Noise Wall Profile Assessment) TRB ADC40 Summer Meeting July / Asheville, NC

2 INTRO BACKGROUND Senior Traffic Noise NCDOT BSME (UMCP, May 1993) Acoustics by OJT in mechanical design & mfg. (Making toy trains of all things ) Focus / specialized in TNM for 10+ years (Since Dec. 2001: Traffic & construction noise only, for better & worse) Traffic Noise C.V: ~18,000 TNM model iterations, >5,000 TNM modeled receptors, >1,000 monitoring locations, >100 noise wall & berm profiles TNM High-end user out of necessity

3 INTRO NCDOT ABATEMENT HISTORY TRAFFIC NOISE ANALYSES / ANALYSTS DO TWO THINGS: 1. DEFINE IMPACTS (traffic & construction ) 2. RECOMMEND ABATEMENT (or not ) Wall or No-Wall?

4 INTRO NCDOT ABATEMENT HISTORY UT PROSIM (that I may serve) The PHYSICAL result of our work is to ABATE traffic & construction noise. As PUBLIC SERVANTS (consultants, too), we owe it to the PUBLIC to do it right. quality and cost are NOT related

5 INTRO NCDOT ABATEMENT HISTORY DEFICIENT ABATEMENT ( UGLY NOISE WALLS) COARSE TNM Modeling = COARSE Wall Specification Final wall design left to Pre-Casters, Contractors, Divisions (Actual noise wall envelope from NCDOT plan sheet)

6 INTRO NCDOT ABATEMENT HISTORY DEFICIENT ABATEMENT ( UGLY NOISE WALLS) COARSE TNM Modeling = COARSE Wall Specification Final wall design left to Pre-Casters, Contractors, Divisions Noise Wall / I-440 / Raleigh, NC (Coarse is generally OK along EOP)

7 INTRO NCDOT ABATEMENT HISTORY DEFICIENT ABATEMENT ( UGLY NOISE WALLS) COARSE TNM Modeling = COARSE Wall Specification Final wall design left to Pre-Casters, Contractors, Divisions Noise Wall / US 1 US 64 / Cary, NC (Coarse is not so good at TOC / ROW)

8 INTRO NCDOT ABATEMENT HISTORY DEFICIENT ABATEMENT ( UGLY NOISE WALLS) COARSE TNM Modeling = COARSE Wall Specification Final wall design left to Pre-Casters, Contractors, Divisions Noise Wall / I-85 / Salisbury, NC (8 vertical steps for ~ 1 mile long wall)

9 INTRO NCDOT ABATEMENT HISTORY Why are our NOISE WALLS so d----d UGLY??? Judge Robert Collier, Chairman, North Carolina Board of Transportation

10 NCDOT Smooth Barrier Design How? TRAFFIC NOISE ABATEMENT IS BUILT FOR THE RECEIVERS NOT THE SOURCE (except maybe for a few test-bed samples)

11 NCDOT Smooth Barrier Design How? By changing TNM modeling focus from Sources to Receivers (Roadways to NSLUs) From This

12 NCDOT Smooth Barrier Design How? By changing TNM modeling focus from Sources to Receivers (Roadways to NSLUs) To This:

13 NCDOT Smooth Barrier Design How? How do NCDOT get smooth barrier designs? BETTER input models Work outside TNM

14 NCDOT Smooth Barrier Design How? So how SHOULD barriers get modeled?... As FLAT as possible As CONSISTENT SLOPE(S) as possible CONVEX top-of-barrier profile BARRIER HEIGHTS = IRRELEVANT* ELEVATION, ELEVATION, ELEVATION *Not too tall, and not too short.

15 NCDOT Smooth Barrier Design How? So how SHOULD barriers get modeled?... Start with MAX HEIGHT segments SMOOTH numerically to refine input profile

16 NCDOT Smooth Barrier Design How? So how SHOULD barriers get modeled?... Start with MAX HEIGHT segments SMOOTH numerically to refine input profile

17 NCDOT Smooth Barrier Design How? Resulting input barrier has constructible profile: Start with MAX HEIGHT segments SMOOTH numerically to refine input profile

18 Smooth Barrier Design Conclusions This wall becomes this wall:

19 Smooth Barrier Design Conclusions Which became this wall:

20 Smooth Barrier Design Conclusions Starting With a SMOOTH TNM Input Barrier: REDUCES SBA TIME REDUCES TNM RUN-TIME IMPROVES BARRIER DESIGN IMPROVES NOISE LEVEL REDUCTION IT S ALL ABOUT THE NOISE

21 IT S ALL ABOUT THE NOISE High Ridge Road: Built 1956 I-95 Completed 1971 Noise Wall 2002 Pool Added 2003

22 NCDOT Smooth Barrier Design References Bowlby, W.; Wayson, R.L. Advanced Traffic Noise Modeling [proceedings of TNM version 2.0 training workshop]. Bowlby & Associates, Inc., Franklin, TN. March 11-15, Mann, Matthew. Discussions pertaining to TNM modeling. January 2002 April Maryland State Highway Administration. High Ridge Highway Noise Measurement and Sound Barrier Analysis Report. September North Carolina Department of Transportation. Traffic Noise Abatement Policy. July North Carolina Department of Transportation. Traffic Noise Analysis and Abatement Manual. August North Carolina Department of Transportation. Traffic Noise Analysis I-40 Widening From I-440/US 64 to NC 42. September 2010.