173 Motorway sound insulation

Shinko Wire Company Ltd has developed ALPORASĀ® for use as soundproofing material that can be installed along the sides of a road or highway

Figure 17.4 Highways, high traffic volume and high residential development create the need for sound-management systems. (Courtesy of Shinko Wire Company Ltd.)

to reduce traffic noise.* With the development of extensive highways and the increase in traffic volume and the density of residential development, noise pollution and other environmental problems have assumed greater prominence, creating the need for sound shielding. A proprietary treatment of ALPORAS (see Chapter 2, Section 2.3) gives a foam structure with enhanced sound-absorbing capability. The structure features a layer of foamed aluminum that is attached to either concrete or galvanized steel with an air gap of calculated width to maximize absorption. The foamed aluminum faces the road to maximize sound absorption. The concrete or galvanized steel backing acts as a sound insulator, keeping the noise from reaching surrounding residents.

Shinko claim that the material is fire resistant, does not generate harmful gases in the presence of a flame, has excellent durability and resistance to

* Shinko Wire Company Ltd, Alporas Division, 10-1 Nakahama, Amagasaki 660, Japan. Phone: (06) 411-1061; fax (06) 411-1075.

Drillfix AG, Drillfix European Distribution, Herrenmatt 7F, CH-5200 Brugg, Switerland. Phone (41) 56 442 5037; fax (41) 564423635.

Figure 17.5 (a) Sound-absorbing lining on the underside of a highway bridge; (b) the sound-absorbing elements are shaped like hemi-circular tubes

weathering, does not absorb water, and can be washed down to keep it clean. The sound-absorbing structures have some shock-absorbing capacity, an attractive appearance, and act as electromagnetic shields, limiting ignition and other electromagnetic disturbances from passing vehicles, and shock waves caused by tunnel sonic boom from ultra-high-speed trains.

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