## 3 Application of Drive-by Methodologies on the Bridge Subsystem
### Bridge Modal Identification
#### 3.1.4. Summary of the Discussed Literature on Bridge Modal Identification
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reference** & **Modal Parameter** & **Study Type** & **Methodology** \\ \hline [PERSON] et al. [32] & NF & A/N & \begin{tabular}{c} Analytical solution by single-mode approximation validated by \\ FEM. Frequency derived from Fourier transform of \\ vehicle response. \\ \end{tabular} \\ \hline [PERSON] and [PERSON] [33] & NF & A/N & \begin{tabular}{c} Analytical solution by mode superposition validated by FEM. \\ Frequency derived from Fourier transform of vehicle response. \\ \end{tabular} \\ \hline [PERSON] and [PERSON] [34] & NF & N & \begin{tabular}{c} Vehicle response signal decomposition by the EMD and \\ assessment of the suspension damping influence on \\ the identification. \\ \end{tabular} \\ \hline [PERSON] and [PERSON] [36] & NF & E & FFT of the vehicle’s acceleration measured while \\  & & & crossing a bridge. \\ \hline [PERSON] et al. [37] & NF & N & Residual frequency spectrum from consecutive vehicles. \\ \hline [PERSON] et al. [38] & NF/MS & N & Calculation of time-domain residual response from consecutive \\ vehicles and the FFT and STFT. \\ \hline [PERSON] et al. [39] & NF & N & Bandpass filter and singular spectrum analysis. \\ \hline [PERSON] et al. [40] & NF/MS & A/N & \begin{tabular}{c} Contact-point response from closed-form solutions \\ verified by FEM. \\ \end{tabular} \\ \hline [PERSON] and [PERSON] [41] & NF & A/N & \begin{tabular}{c} Expressions derived for the contact-point response from \\ in-vehicle data. Natural frequency extraction from \\ FFT spectrum. \\ \end{tabular} \\ \hline [PERSON] et al. [42] & NF & A/N & FFT of contact response derived from analytical expressions \\  & & & validated by FEM. \\ \hline [PERSON] and [PERSON] [43] & NF & A/N & \begin{tabular}{c} Residual frequency spectrum calculated from the \\ contact-point responses. \\ \end{tabular} \\ \hline [PERSON] et al. [23] & NF & N & FFT and CWT coefficients of the bogie’s responses at \\  & & & candidate frequencies. \\ \hline [PERSON] et al. [24] & NF & N & FFT of the time-domain residual response. \\ \hline [PERSON] et al. [25] & NF & N & Combined residual response of several consecutive vehicles. \\ \hline [PERSON] and [PERSON] [45] & NF & N & \begin{tabular}{c} Frequency content of IMFs derived from the EMD of the \\ vehicle’s response. \\ \end{tabular} \\ \hline [PERSON] and [PERSON] [46] & NF & N & \begin{tabular}{c} Frequency content of IMFs derived from the EEMD of the \\ vehicle’s response. \\ \end{tabular} \\ \hline [PERSON] et al. [26] & NF & E & \begin{tabular}{c} HHT of measured bogie acceleration responses of several \\ train crossings. \\ \end{tabular} \\ \hline [PERSON] et al. [27] & NF & N/E & \begin{tabular}{c} NN trained based on the FFT of wheelset \\ acceleration responses. \\ \end{tabular} \\ \hline [PERSON] et al. [48] & MS & A/N/E & \begin{tabular}{c} Acceleration response of a vehicle equipped with a \\ sinusoidal exciter. \\ \end{tabular} \\ \hline [PERSON] et al. [30] & MS & A/N & \begin{tabular}{c} Amplitude of the analytical signal derived from the HT of the \\ bridge-related components of the vehicle response. \\ \end{tabular} \\ \hline [PERSON] et al. [29] & MS/DR & A/N/E & \begin{tabular}{c} HT of vehicle response combined with a correction function for \\ bridge damping. \\ \end{tabular} \\ \hline [PERSON] and [PERSON] [31] & MS & N & Short-Time Frequency Domain Decomposition technique. \\ \hline [PERSON] et al. [50] & MS & N/E & Acceleration signal envelop of bridge-related components of \\  & & & vehicle response. \\ \hline [PERSON] et al. [51] & MS & A/E & \
\begin{tabular}{c} CWT of the response of a crowd of sensors. \\ \end{tabular} \\ \hline [PERSON] et al. [28] & DR & N &
\begin{tabular}{c} Reverse dynamic modeling to derive the damping ratio which \\ provides the lower squared error between the estimated \\ irregularity profiles under each wheel. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Summary of the presented works in drive-by modal identification.