Mitigation of ground borne noise in rock railway tunnels - Part II: Full scale tests

Abstract

Railway trafc in shallow depth rock tunnels can give unacceptable levels of ground borne noise in buildings above the tunnel. For such a tunnel under construction in Norway
a project was commissioned by the Norwegian Rail Administration (JBV) to design the most cost effective track that satised the prescribed residential sound levels. A component of
this project was a series of full scale tests. This, the second part of a two part paper, discusses these full scale tests and compares the measured results against those predicted by the simulation work of the rst part of the paper. For each of the seven track substructures tested the acceleration of the rail, sleeper, tunnel oor and tunnel wall were recorded, in addition to the acceleration at various depths throughout the track substructure. Vibration and sound were also measured in the houses above the tunnel. The input to the entire system was via a fully laden freight wagon which had a dynamic excitation force applied to one axle. This force was excited by a hydraulic actuator which, operating under force control, delivered excitation in sweeps of one-third octave bands that covered the relevant frequency range. This paper presents the testing  program and corresponding results, and compares these results with the predictions of the companion paper.