ADVANCEMENT OF THE EUROPEAN METHOD FOR IN-SITU MEASUREMENTS ON ROAD TRAFFIC NOISE BARRIERS

The EN 1793-5 and -6 method for measuring the intrinsic acoustic characteristics of noise barriers along motorways (a.k.a. Adrienne method) has been in use for many years and has proven to be robust and provide highly repeatable results. However, some aspects of the method can still be improved. For example, when measuring along a motorway open to traffic or when the entire length of the barrier needs to be evaluated, measurements need to be made quickly and efficiently; on the other hand, accurately positioning the equipment may be time consuming. Therefore, Autostrada del Brennero and University of Bologna developed a frame for the measuring equipment, to be quickly transported on the test site and positioned with a crane truck. The first results seem very encouraging, however a detailed study of the repeatability that can be expected during a full-day measurement session on the field is still lacking. This study has been done and is presented in this paper, where the new system is compared with the standard system used at University of Bologna to make the background study for EN 1793-5 and EN 1793-6. Repeated sequences of in-situ measurements have been done with both systems on the same noise barriers and the standard deviation of repeatability has been derived. It is concluded that the new rigid supporting frame has a better standard deviation of repeatability compared to a state-of-the-art equipment.