Acoustic assessment of micro-pressure waves radiating from tunnel exits of DB high-speed lines

Abstract

In December 2005, when first test runs were carried out on the new high speed line Nuremberg-Ingolstadt, significant sonic boom incidents occurred at the portals of the 7700 m long Euerwang tunnel and the 7260 m long Irlahüll tunnel. Both double-tracked tunnels with a cross-section of 92 m2 were originally planned to be built with ballasted track. When a change to slab track was decided, no changes in the design of the already built tunnels were introduced. DB decided to take immediate countermeasures by equipping the two tunnels with acoustical track absorbers. These absorbers are designed to counteract railway rolling noise, but also affect the pressure wave steepening process. Thus a significant reduction of the micro-pressure emission was achieved and the commercial operation on Nuremberg-Ingolstadt line started in Mai 2006 successfully in time and without operational restrictions. This paper presents the acoustical measurements outside the tunnels and their assessment based on national traffic noise regulations for the neighbourhood, LCpeak for possible health hazards nearby the tunnel portals and LCE for comparison the micropressure effect with a train pass-by. © 2008 Springer-Verlag Berlin Heidelberg.