After the Humen Bridge in China displayed excessive oscillations in 2019 - 22 years after its completion - vibration tests and a wind study were conducted to identify the cause. With the determination of the natural frequencies and vibration modes it could be concluded that the deck oscillations were due to vortex shedding. Control measures were investigated during wind tunnel studies and it was decided to implement Tuned Mass Dampers to reduce the vortex shedding induced oscillations by increasing the structural damping of the bridge for these modes. The paper herein presented describes the optimization approach which has been undertaken to implement Tuned Mass Dampers in practice, give the very low Eigenfrequencies, the limited space in the bridge deck and the requirement for subsequent installation. Furthermore, results of the monitoring campaign without and with TMDs will presented, which allow wind speed correlations and verified the effects that were investigated during the wind tunnel test. The key parameter to assess the effectiveness of the Tuned Mass Dampers is the structural damping, so a focus of this contribution will be the different methods for in situ damping estimation using the ambient vibration signals. The damping estimation not only allows to monitor the TMD operations but also to assess the dependency of the damping values to the type of excitation resp. the wind speed.