As part of Main Roads Western Australia's (MRWA) bridge management and bridge upgrading program, MRWA bridge no. 3014 was assessed to evaluate its condition before and after strengthening works with carbon-fiber-reinforced-polymers (CFRP). The assessment process coupled analytical results with field observations and dynamic testing of the structure. Vibration-based structural assessment of the bridge was conducted before and after the completion of the upgrading works. This paper presents the results of the vibration tests and modal analysis performed before and after the structure upgrading. In particular, the change in the structural properties and stiffness, before and after the strengthening, based on the analyses of the updated models of the bridge, is presented and discussed. The results demonstrate the effectiveness of using the dynamic assessment method to determine the elastic flexural stiffness of bridge structures retrofitted with CFRP.