Many methods of damage identification in bridge structures have focused on the use of either numerical models, modal parameters or non-destructive damage tests as a means of condition assessment. These techniques can often be very effective but can also suffer from specific pitfalls such as, numerical mod-el calibration issues for nonlinear and inelastic behaviour, modal parameter sensitivity to environmental and operational conditions and bridge usage restrictions for non-destructive testing. The present paper covers al-ternative approaches to damage identification of bridge structures using empirical parameters applied to measured vibration response data obtained from two field experiments of progressively damaged bridges sub-jected to ambient and vehicle induced excitation, respectively. Numerous non-modal vibration-based parame-ters are detailed and selected for the assessment of either the ambient or vehicle induced excitation data based on their inherent properties.