What you measure is what you get? - a novel approach for specifying and controlling acoustic quality of road surfaces
Invited paper
M+P
Tuesday 2 june, 2015, 11:00 - 11:20
0.2 Berlin (90)
Abstract:
Low-noise road surfaces are very effective noise reduction measures for traffic
noise. These roads are designed such that road texture and acoustic absorption
are optimal for a certain traffic mix. But they should also comply with (civil
engineering) boundary conditions such as durability, friction and rolling
resistance. The optimal design for a certain road is then often expressed in
civil engineering terms like stone mixture, grading curve, layer thickness, and
porosity. But knowing the optimal parameters is only half of the story: How to
treat deviations from the optimal recipe? Can less porosity be compensated for
by a thicker layer? What if we change the granulate supplier? Does the road
surface still perform within the limits that are set by the client or the
environment?
For the reconstruction of the main highway in the Rotterdam harbor area, we
were faced with these questions. The road surface for this road was optimized
for maximum noise reduction and durability, knowing that there is a
significantly larger amount of truck traffic on this road than on any other
road in the Netherlands. In a joint effort, the constructor, acoustic
consultant and client decided on a new approach to specify and evaluate the
acoustic quality. We used parameters that civil engineers can obtain easily and
on the same time accurately predict acoustic quality. By taking drill core
samples from the road, using absorption measurements and the SPERoN tyre/road
noise model, we are able to devise a two parameter characterization (layer
thickness and degree of compaction) of the road surface. This characterization
is now used by the contractor to demonstrate that the road surface they build
complies with the client’s wishes.