||Colas, the leading road construction and
maintenance group - and its subsidiary, Somaro, a specialist
in safety equipment and road signs and signals - in partnership
with the Ecole Polytechnique, have developed a new type
of noise barrier for roads with an unequalled level of
Depending on the configuration, the barrier’s performance
is 30% to 50% greater than that of the most effective sound
panels currently available on the market.
This innovative product, for which a patent application has
been filed and which has earned the Siemens Prize for Applied
Research 2003 for the Ecole Polytechnique (the reputed French
school of engineering), is based on a number of theoretical
and experimental studies on the properties of irregularly
It has been proved that the geometry of objects is of great
importance in the deadening of noise. Resonators with a jagged
or ragged geometrical shape can therefore deliver better sound
deadening than ordinary geometrically smooth systems.
Considering these properties - and bearing in mind, moreover,
that it is very difficult to manufacture irregularly shaped
objects using inexpensive industrial processes (such as moulding,
for instance) - the challenge for the team consisted in developing
the morphology of an acoustically absorbent material that
would be appropriate for moulding.
|A prototype was built in the form of a panel measuring
4m by 4m, associating a very sophisticated surface morphology,
composed of cone and pyramid frustums arranged in repetitive
fashion, with the use of wood-cement concrete. (A frustum
is the remainder of a pyramid or cone whose upper section
has been cut off by a plane parallel to its base).
Measurements performed in a reverberation chamber — as stipulated
by the standards in force — have resulted in the classification
of the new noise barriers in the ‘very high absorption’
category, with unrivalled performance.
This new high-performance soundproofing wall is perfectly
adapted to a motorway environment and is ideal for entrances
to tunnels with heavy traffic. However, the technology is
also suitable for high-speed railway lines and busy airport
With a cost that will remain competitive - and a design enabling
it to blend easily into landscapes - Colas’ noise barrier
should soon undergo significant industrial and commercial
development for the greater benefit of local neighbourhoods
currently affected by noise pollution.
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