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Ground Attenuation, Barriers and Distant Receivers

Ground Attenuation, Barriers and Distant Receivers. Lloyd Herman Ohio University. Distant receivers. Location: 0.4 – 3.2 km (¼ to 2 mi) from highway Problem: complaints of increased noise levels after barrier construction. California experience. Hendriks and Hecker 1989

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Ground Attenuation, Barriers and Distant Receivers

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  1. Ground Attenuation, Barriers and Distant Receivers Lloyd Herman Ohio University

  2. Distant receivers • Location: 0.4 – 3.2 km (¼ to 2 mi) • from highway • Problem: complaints of increased noise • levels after barrier construction

  3. California experience • Hendriks and Hecker 1989 • I-405 in LA • Receivers: 0.3 – 0.6 km (0.2 – 0.4 mi) • Woodward-Clyde & Illingworth and Rodkin • 1994 • I-680 in SF Bay area • Receivers: 0.4 – 1 km (0.25 – 0.67 mi)

  4. Ohio experience • I-71 in southern Ohio • Receivers 0.2 – 0.5 km (0.1 – 0.33 mi) • SR8 in northern Ohio • Receivers 0.2 – 0.8 km (0.15 – 0.5 mi)

  5. Survey of 1200 residents • 35% said noise levels increased • The most complaints: • 0.2 – 0.3 km (0.15 – 0.2 mi) • located in parallel barrier sections

  6. Barrier attenuation and path length difference Receivers b Source d a c

  7. Sound path

  8. Attenuation Mechanisms Geo Sprd Atm Barrier Ground Meas. Level Source Level

  9. Ground Attenuation R S • Path length difference • Air to ground impedance ratio • Angle of incidence

  10. Ground effect Source: Piercy and Embleton, JASA 61 1403-1418

  11. Before barrier construction Source Level Geo Sprd Atm Barrier Ground Meas. Level

  12. After barrier construction Source Level Geo Sprd Atm Barrier Ground Meas. Level

  13. High and Low source levels Site: Cinderella

  14. High and Low source levels Site: Kenwood Meadows

  15. High and Low source levels Site: Glenover

  16. High and Low source levels Site: Delray

  17. High and Low source levels Site: Cooperwood 1

  18. High and Low source levels Site: Cooperwood 2

  19. After barrier construction Source Level Geo Sprd Atm Barrier Ground Meas. Level

  20. Parallel barrier degradation

  21. …no conclusions! Ideas, Thoughts, Comments, Questions?

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