INTER-NOISE 2006 3-6 DECEMBER 2006 HONOLULU, HAWAII, USA Case history: in situ verification of the intrinsic characteristics of the acoustic barriers installed along a new high speed railway line Massimo Garai a DIENCA - University of Bologna 2 Viale Risorgimento Bologna, 40136 Italy Paolo Guidorzi b DIENCA - University of Bologna 2 Viale Risorgimento Bologna, 40136 Italy ABSTRACT In September 2005 the new high speed railway line Torino-Novara, Italy, was under completion and the acoustic barriers just installed according to the specifications. The authors did here the in situ verification of the intrinsic characteristics of the noise reducing devices, an essential part of the specifications. It is the first European experience of this kind on a large construction workplace. The conditions were extremely demanding and the time scheduled for the task very short. The challenging task was successfully completed applying CEN/TS 1793-5 and requesting a specific logistic support. The paper reports the key points of this successful experience and shows some exemplary results. The values measured in situ are compared with the results obtained some years ago on products of the same kind. The comparison is in favour of the reliability of the measurement method and gives some indications on its reproducibility. It is concluded that the selected method is fully adequate to in situ verification and could be repeatedly applied to check the acoustic durability of noise reducing devices over time. 1 INTRODUCTION The new high speed railway line Torino-Novara, Italy, was opened in February 2006. About 100 000 m 2 of acoustic barriers have been installed along the 86 km of the line, to protect the environment from the noise emitted by trains (see Table 1). Table 1: Types of acoustic barriers installed along the Torino-Novara railway line. Barrier type Installed quantity Percentage Metallic cassettes filled with glass wool 25 000 m 2 25% Timber and metal cassettes filled with glass wool 25 000 m 2 25% Concrete panels with a porous side 30 000 m 2 30% Acrylic sheets and concrete panels (reflective) 15 000 m 2 15% Others 5 000 m 2 5% In September 2005 the noise screens were almost all installed and the authors were asked to verify their acoustic intrinsic characteristics: this means to measure the airborne sound insulation and reflection characteristics (which are different from the insertion loss) on site. The task was very demanding; in fact, it was requested to carry out the measurements: ｾ according to high quality technical standards; ｾ on site during the final phase of the construction work; ｾ beginning 3 days after the signature of the contract; ｾ ending in 7 days; a Email address: massimo.garai@mail.ing.unibo.it b Email address:paolo.guidorzi@ mail.ing.unibo.it