PROJECT DESCRIPTION
BACKGROUND
European cities are facing great environmental challenges, including noise pollution and climate change, which have major consequences for the health of inhabitants. It is estimated that 37 million European citizens are exposed to transport-related noise at levels considered dangerous for their health. In Paris, about 22% of the population is affected by noise pollution, mainly caused by road traffic.
Climate change is also a major concern for the most densely populated European cities. Studies have shown that over the past 30 years heat waves have become increasingly intense and longer in Europe, and their impact on health is higher in urban areas than elsewhere. This can be explained by the so-called urban heat island effect, characterised by higher air and surface temperatures in urban areas than in the rural periphery.
OBJECTIVES
The LIFE C-LOW-N ASPHALT project aimed to tackle traffic noise and the urban heat island effect by developing three new types of asphalt road surface. These had phonic and thermal properties to reduce noise pollution and mitigate temperature rises in cities. The project sought to refine the properties of two widely used asphalt concrete mixes and one mastic asphalt mix, including cost-effectively enhancing their durability. This would enable the new formulas to be used for road surfaces across the EU.
On the thermal side, the aim was to mitigate the urban heat island effect by testing the water retention capacity, the micro-climatic impacts generated by sprinkling during summer peaks and the effects of their colour on heat restitution of pavements.
This produced positive effects for climate adaptation. The project also contributed to the Environmental Noise Directive (2002/49/EC - END) by helping to reduce traffic noise in urban areas.
RESULTS
As planned, the LIFE C-LOW-N ASPHALT project developed 3 innovative road pavement formulas (SMAphon, BBphon+ and PUMA) and successfully deployed them on 3 Parisian streets, where their acoustic, thermic/microclimatic and mechanical performances, expected to be better than the conventional pavement, were assessed.
Regarding the acoustic aspects, the gains are satisfying: by the end of the project, the best performances when comparing to the reference pavements were obtained for the BBphon+ in the rolling noise (CPX) with -1,3 dB(A) and for the SMAphonin the ambient noise with – 2,8 dB(A), and the initial targets expected after 5 years were -2 dB(A) in the rolling noise and – 1 dB(A) in the ambient noise (page 19-20 of the Layman’s report).
Based on the trends observed during the project, it is estimated that the innovative materials can offer an acoustic gain of over 7 years when comparing to the existing conventional pavements.
The results in terms of thermal and micro-climatic performances are, however, to be treated with caution. Firstly, the effect of the innovative material alone (without watering) could only be studied for the BBphon+ which was found to generate a deterioration of the microclimatic conditions in-situ compared with the pre-existing conventional pavement. The water spreading of the innovative materials led to more positive results though with a reduction in the heat stress of 1°C for the SMAphon and of 2-3°C for the BBphon+ and the PUMA.
The mechanical performance and durability of the innovative materials were found to be as good as the conventional pavements’ ones.
Although the results are lower than expected, the environmental impacts as well as the socio-economic impacts linked to the acoustic gains were measured satisfactorily and demonstrated to be non-negligible and positive when considering health and productivity aspects.
