Noise reducing screen

A noise reducing screen disposed between and elongated noise source and a building having a continuous wall portion to be shielded from the noise source and located along one side of the elongated noise source;

• said noise reducing screen comprising:
• a continuous tunnel portion having a whole length 2d enclosing a portion of said elongated noise source;
• said tunnel portion built up on both sides of a perpendicular drawn from the building which is the most remote from the noise source and is located at a distance D therefrom to said elongated noise source;
• a plurality of variably spaced apart gantries each comprising two posts and a beam aligned with said tunnel portion and perpendicular to said elongated noise source;
• the posts and the beams of said gantries having a length a and and width b respectively parallel and perpendicular to said elongated noise source;
• the spacing between the n.sup.th and (n-1).sup.th gantries being at most equal to
• dp.sup.n + (a-d)p.sup.n-1 with n .ltoreq. 2 (and n=1:dp) where p is the ratio D/(D-b);
• whereby all rectilinear noise propagation path from said noise source to said building are intercepted by the posts and the beams of said gantries;
• and
• noise absorbent means on said gantries.