Airborne noise attenuation techniques in close curves from athens tramway operation
TRAM S.A. in order to manage the problem of "squealing noise", generated at close curves of its network, applies special bio-degradable grease on the side of the track way. A complete measurement campaign was executed with the participation of The University of Thessaly -Dept. of Civil Engineering, regarding airborne noise levels (before) and (after) the application of a special bio-degradable grease substance on the tracks at Kassomouli pedestrian area. Several tram pass byes were monitored for the same trains in order to assess the effectiveness of the method in similar real time conditions. For every tram pass bye all acoustic indices were measured and in particular Leq, Lmax & Lmin, using a set up including simultaneous recordings with two microphones at a distance in between of 12 meters (inlet and outlet of the curve), and at 0, 7 meters height. The distance from the internal rail was fixed at 1, 0 meter for both microphones. This article presents and evaluates the: • fluctuation of the Leq index for all 5 tram vehicles before and after the intervention and • all airborne noise levels and especially of the recorded noise attenuation due to the use of this particular biodegradable substance.