Sound barriers | Bissone | 2010
Study of the regional natural morphology for a state-of-the-art work
Bissone - USTRA
Melide - Dipartimento del Territorio
Engineering and Architectural firm
RiMeBi Group (Tunesi Luigi Ingegneria SA / Studio d'ing. Simona / IFEC Consulenza SA / Studio d'arch. Valeggia)
Officine Ghidoni SA - Ferriere Cattaneo SA - Tubosider SpA
The stretch of A2 highway in Melide bridge-dam area is characterized by considerable traffic and a layout that actually halves the built up area of Melide and mainly the one of Bissone, thus obviously causing a considerable acoustic load, since the residential area is close to it.
So an acoustic reclamation of the area was indispensable, and the only actual chance we had was to place sound barriers in just next to the highway stretch.
-the side acoustic walls have a zigzag geometry, whereas, generally, the greater part of the sound barriers shows a very lightly structured surface
-an heavy layer, that allows to achieve better sound insulation performance, with respect to ̒standard̕ similar products on the market, makes the metal walls weighty inside
-in Bissone area, some partial ̒umbrella̕ coverings had been built too on the highway
-the flooring is drainage type – PA8 – and it is not particularly familiar on flyovers
-Thanks to the four above-mentioned aspects, noise abatement is particularly significant and it hits maximum values around 18 dB (A) in Bissone, whereas, in Melide, the maximum abatement is around 9 dB(A) and in Carona – mainly thanks to the effect of the draining flooring – is around 5 dB (A).
In Bissone the acoustic reclamation work consisted in building two different typologies of modular panel elements to be assembled one another. The first one consists of a slightly curved element to be used as a semi-covering of the highway site; the second angle- sectional developed one forms the vertical safeties section.
The acoustic shielding consists of metal carpentry structures, fastened to reinforced concrete and prestressed stands, that sustain the aluminum alloy sound-absorbent panels.
SIA requirements, held true during the planning stage, had been studied for the various concrete and steel elements dimensioning. The Swiss Federal Institute of Technology – EPFL – laboratories, in Lausanne, analyzed the action made by the wind on the semi-coverings.
The sound-absorbent flooring of the whole highway stretch between the two tunnels portals improved the acoustic shielding efficacy.
The various assembly steps evolved in three different steps in the summer of 2009/2010/2011.
The traffic divider wall assembly had been certainly the most delicate operation because it was needed to work over the traffic no disturbing it. The hard working conditions brought to build a particular self-propelled equipment, that had to be whether a protection or a supporting base for the assembly process or a material stock place, as the supply could only take place through a South to North lane and in two time-courses. The assembly process synchronization had to be perfect; it was essential to go ahead with a ̒finished̕ protection, since it was actually impossible to move previously assembled elements again.