## 2 Literature Review
\begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Authors (Year)** & **County/Region Being Investigated** & **Method** & **Contributions** & **Gap** \\ \hline
[8] & Spain & Distance function &
\begin{tabular}{c} Provide evidence on the way \\ realocation of resources and \\ management incentives \\ affects efficiency \\ \end{tabular} & There is no second-stage analysis. \\ \hline
[9] & Europe & Frontier functions & \
\begin{tabular}{c} Investigate the impact of \\ regulation on efficiency \\ \end{tabular} &
\begin{tabular}{c} Only the impact of regulation is \\ investigated, no implications are \\ provided from the perspective \\ of operation. \\ \end{tabular} \\ \hline
[10] & Europe & \begin{tabular}{c} Displaced ordinary least \\ squares measure \\ \end{tabular} & \
\begin{tabular}{c} Decomposition of overall \\ performance into managerial \\ perspective and policy perspective \\ \end{tabular} &
\begin{tabular}{c} Related to managerial perspective, \\ no specific information is provided \\ related to exactly how to improve \\ the performance. \\ \end{tabular} \\ \hline
[11] & Europe & \begin{tabular}{c} Performance is measured by length of \\ rail track, annual number of rail \\ passengers, annual number of victims \\ and seats and berths. \\ \end{tabular} & \
\begin{tabular}{c} Compare statistical data on various \\ passenger-related parameters of the \\ railway system \\ \end{tabular} &
\begin{tabular}{c} The performance is measured by \\ relevant statistics rather than under \\ a scientific method, the accuracy of \\ the results should be improved. \\ \end{tabular} \\ \hline
[12] & Japan & \
\begin{tabular}{c} Nonparametric productivity \\ measurement \\ \end{tabular} & Estimate social efficiency &
\begin{tabular}{c} No information can be confirmed \\ through investigation \\ how to improve the \\ social efficiency. \\ \end{tabular} \\ \hline
[13] & Netherland & \begin{tabular}{c} Performance is measured by \\ punctuality and train cancellation \\ \end{tabular} & \
\begin{tabular}{c} Investigate the impact of weather on \\ railway operator performance \\ \end{tabular} &
\begin{tabular}{c} The idea is unique while \\ investigating this uncontrollable \\ factor on performance generates no \\ managerial implications. \\ \end{tabular} \\ \cline{3-3}
[14] & Belgium & Data envelopment analysis & \
\begin{tabular}{c} Pinpoint staff schedule inefficiencies \\ as well as highlight operational safety \\ risk \\ \end{tabular} &
\begin{tabular}{c} The is a one-way investigation of \\ the impact of efficiency on human \\ error with no attempt made to \\ examine the cause–effect relationship. \\ \end{tabular} \\ \hline
[15] & Taiwan & \begin{tabular}{c} Performance is measured by \\ passenger satisfaction index \\ through surveys \\ \end{tabular} & \
\begin{tabular}{c} Propose a novel PSI model integrated \\ with a modified IPA technique and \\ through which identity top-priority \\ performance evaluation indicators \\ \end{tabular} &
\begin{tabular}{c} No information is provided related \\ to the operations’ perspective. \\ \end{tabular} \\ \hline
[16] & Taiwan & Short-run translog cost function & \
\begin{tabular}{c} Estimating cost structure and \\ productivity growth in the context of \\ Taiwanese railway \\ \end{tabular} &
\begin{tabular}{c} Limited number of factors \\ examined, and no cause–effect \\ relationship investigated. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Review of previous literature studies.