This paper presents a research to assess real estate gains brought by a new light rail infrastructure: the T3 tramway line in Paris opened in December 2006. Based on comprehensive geolocated data, it mainly focuses on econometric hedonic modelling where accessibility gains are included besides other intrinsic and extrinsic variables. In spite of different specifications, no model yielded any significant effect of the new line. Finally, the rationale for such an outcome is discussed, and by comparison with other studies, the factors for a new line to provide significant gains are listed.