This article presents and discusses full-scale stay cable vibration tests carried out by DYWIDAG on an extradosed bridge. Firstly, the evaluation of cable forces using the vibration method is presented. The applicability of the vibration method is demonstrated by comparing the calculated cable forces with lift-off readings. Secondly, the damping identification of stay cables with removed and installed rubber dampers (consisting of three high damping rubber (HDR) pads) in full-scale in-situ tests is shown. Finally, the identified damping efficiencies are compared with the damper design, highlighting the proven high performance of installed rubber dampers.