Rosão, VitorConceição, E. Z. E.Marques, T.2016-01-272016-01-2720109781617823961AUT; ECO01058;http://hdl.handle.net/10400.1/7514The purpose of this study is to determine the variability of noise levels associated with the pass-by of the same type of train at a point, near a railway, and compare this variability with the standard uncertainty, due to the operation of the source, established in ISO 1996-2: 2007, and in the document "Determination of Lden and Lnigth Using Measurements: 2006", from the European Work Group IMAGINE. With these results we can know the measurement effort required to achieve a certain standard uncertainty.engconference object