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Environmental products

Sudden noise absorber (joint noise suppression method for bridges)

Patent No. 4982767

NEXCO East Japan Engineering Co., Ltd.
Product Summary

Joint development: East Nippon Expressway, Ltd. and Shizushina Co., Ltd.

  1. In order to reduce the sudden noise that occurs when a vehicle passes through a bridge joint, we have developed a product that uses lightweight materials with high sound absorption properties and can be easily installed in narrow spaces under bridge girders.
  1. It can be fixed to the bridge body with anchor bolts, etc., so it can be easily installed and removed.
  2. The left and right split structure allows for expansion and contraction due to temperature changes.
  3. Since it can be opened and closed, inspection work is easy.
  4. The area directly below the joint is covered with a box-shaped sound absorbing material, eliminating the need for roadside work.
  5. No modification of existing bridges is required.
Features/Specifications

  1. The sound-absorbing panel has a structure in which a ceramic honeycomb core material using sound-absorbing phenol foam is sandwiched together with aluminum plates to ensure the strength of the product as a single product.
  2. The thickness of the parts is as thin as 33mm, and the weight is as light as 8kg/m2, making it easy to cut and bend the parts.
  3. By using an aluminum fiberboard with voids on the sound-absorbing surface (joint side), noise energy is absorbed into the core material and the sound-absorbing function is demonstrated.
  4. In terms of sound absorption performance, it has a sound absorption coefficient of 0.9 or higher in the frequency band of 400Hz or higher, making it possible to absorb and attenuate noise generated in a wide frequency band.

During construction on Kan-Etsu Expressway, the noise level before construction was distributed in the range of 100 to 84 dB(A), but after construction it was 92 to 70 dB(A), indicating a relative decrease in noise level. Masu.
Achievements (sales/construction/introduction)

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