A field test was carried out on a semi-closed noise barrier installed on a high-speed railway bridge.The vibration accelerations of the track structure, box-girder and semi-closed noise barrier were measured under the excitation of wheel/rail dynamic forces.The recorded signals were analyzed both in time domain and one-third octave band frequency domain.Based on the theory of train-track-bridge coupled vibration, a box-girder-noise-barrier coupled vibration model was built to simulate the vibrations of noise barrier.The computed results were compared with measured data to make sure the accuracy of the numerical model.Finally, the numerical model was used to analyze the vibration characteristics of the noise barrier and to discuss several vibration reduction measures.The results show that the vibration attenuation characteristics of the rail, track slab, bearing base, box-girder and noise barrier are consistent with those measured along the vibration transmission path.The dominant frequency ranges of vibrations measured on the vertical strut are located in 20-63 Hz and 100-500 Hz, with peak values at 40 Hz and 125 Hz.The proposed model shows satisfactory accuracy in simulating train-induced vibrations of the box-girder and noise barrier.The integrated vibration acceleration level of noise barrier rises along with the increasing train speeds at a rate of 3.5 dB per 50 km/h.The noise barrier vibrations at mid-span cross-section are more severe than that at other cross-sections, and the vibration of the cross beam is more severe than that of the vertical strut.Increasing the noise barrier stiffness and adding inclined braces at the outer side of the box-girder flange slab can both reduce noise barrier vibrations, and the later measure is verified to be more efficient by simulations.