“…The idea of using indirect methods, known as such because the vibrations on the bridge are never measured directly, was first proposed in [ 13 ] and several studies have been published on this topic since. The focus of the early studies was the identification of highway bridge frequencies using the accelerations obtained from the quarter- or half-car models in numerical simulations [ 14 , 15 , 16 , 17 , 18 , 19 ]. Several other studies then aimed to determine the mode shapes of bridges [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ], to identify and remove the adverse effects of surface roughness [ 27 , 28 , 29 , 30 , 31 ], or to identify the presence of damage [ 32 , 33 , 34 , 35 , 36 ].…”