This report documents the work carried out in investigating Gradient Index Profiles (GIPr for rail, GIPw for wheel and GIP for wheel-rail) along the Swedish Western Main Line connecting Stockholm and Gothenburg. In particular, for all parts of track sections (Bandel, Bdl) including Bdl 410, 412, 416, 511, 512, 611 and 612, this report presents on-track measurement results of GIPr and GIP. The investigations include distribution functions of GIPr and GIP, grouped into three zones based on curve radii, and examine their correlations with both track and in-service equivalent conicities. Based on the findings presented in this report, a comprehensive understanding of wheel-rail geometry contact conditions along the Western Main Line has been achieved, which plays an important role when dealing with running instability issues and in establishing a systematic approach to improve passenger ride comfort.