Concrete Roadways and Air Quality – Assessment of Trials in Vanves in the Heart of the Paris Region

Despite the considerable progress achieved by automakers and public policy efforts to promote '"soft" and "public" travel modes, the air quality of our streets can become critical at singular periods of the year, particularly for the more fragile populations. It is possible today to reduce the most harmful nitrogen oxides, notably N02, using an oxidoreduction phenomenon that generates photocatalysis with titanium dioxide Ti02. A new generation of cements with a photocatalytic effect has made it possible to build a depolluting concrete pavement at Rue Jean Bleuzen in Vanves, very near the Paris ring road, at the initiative of the Hauts de Seine Department and the Vanves Township. In addition to the findings of this whitetopping project in an urban setting, expectations were focused on air quality in terms of N0, N02, and N0x. Extensive continuous measurement installations were set up and analysed for 13 months, from December 2007 to January 2009, so that the evaluation emerging from the technical and scientific capabilities deployed offered truly original results under real field conditions. The paper presents the synthesis of results obtained on air quality, in particular during critical periods and provides the bases for provisional guidelines with respect to the relationship between concrete pavements and air pollution, covering the requirements relative to cost efficiency and specific avenues of progress. The effectiveness of the technique was demonstrated under street typology conditions as well as in relation to the light, wind and temperature around the public space involved. Also highlighted is the strong determination of highway engineering players to join forces and strive to work together towards the development of "greener" roadways in keeping with the goals of the European NR2C (New Road Construction Concept) programme, while complying with the principle of reliable, safe and integrated roadways.