Construction of concrete noise protection barriers

The finalizing of the Federal German-law relating to pollution and nuisance control (Bundesimmissionsschutzgesetz) in April 1974 was an important step in the implementation of active noise control measures. The "Guidelines for traffic noise control on Federal interregional highways" published by the Federal German Minister of Transport in August 1983 establishes a basis for the construction of noise control structures. At present there are in the Federal Republic of Germany some 500 km of noise reduction barriers with a total area of almost 1.7 million m2 . On average, this is increasing by 250,000 m2 per year. Because of their durability and versatility of design, concrete systems have increasingly been used for such structures in recent years. Concrete-and-earth systems, so-called "steep banks", which can be sown with grass can be particularly well integrated in the landscape. They are therefore used wherever the effect of the conventional earth embankment is desired, but not enough space is available for it. A concrete-and-earth system requires about 75% less area on plan. Besides, by combining this with a concrete safety barrier which can be incorporated in the "steep bank", it is moreover possible to reduce the necessary distance from the roadside to about 1.50 m. With a flat noise reduction barrier, the space behind the safety barrier forms a continuous trough along the whole length of the road and can be planted with a variety of vegetation. The trend towards more colour in architecture has led also to better design of noise reduction barriers. Some interesting and trend-setting solutions have been conceived and implemented as a result of collaboration by the highway authorities and landscape preservation associations with independent architects and artists. Highly sound-absorbing lightweight concrete facings can be attractively coloured by the addition of pigments, so that a great many design variants are possible. Smooth. reflecting concrete surfaces may be given coloured coat1ngs. Better harmonization with surrounding landscape can thus be achieved. In this way, too, the rear side of the barrier, facing the adjacent residents, can be given an attractive appearance. The same considerations apply to textured and patterned concrete surfaces, preferably obtained by means of plastic form liners. The attractively moulded shaping of columns, cornices or individual wall sections offers fu:ther scope for the aesthetically creative design of n01se control structures.