## 4 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Year** & **Authors** & **Focus Area** & **CC** & **EC** & **SC** & **LCCA** & \multicolumn{3}{c}{**Overall Findings/Tools**} \\ \hline
2016 & [PERSON] [41] & CIPPRT and
\begin{tabular}{} \\ SimaPro \\ \end{tabular} & ✘ & ✘ & ✘ & ✘ & 0.042 tons over 22 days, compared to 0.181 tons for open-cut methods over 110 days \\ \hline
2017 & [PERSON] et al. [86] & OCPI and TT (Carbon footprint) & ✘ & ✘ & ✘ & ✘ & - & CO\({}_{2}\) produced using TT method was 887 tons and for OCPI was 5379 tons \\ \hline
2019 & ASCE [88] & Manual of Practice (Sustainable design of pipelines) & ✘ & ✘ & ✘ & ✘ & - & EC and SC can be reduced by \\  & & & & & & & & & \\  & & & & & & & & & \\ \hline
2019 & [PERSON] et al. & CIPPRT (Cost & ✔ & ✘ & ✘ & ✘ & - & Do nothing = $9494.85, CIPPRT lining = $6185.37, and mold rubber & \\  & & decision-making) & & & & & & & = \\ \hline
2019 & [PERSON] [33] & \
\begin{tabular}{} \end{tabular} &
\begin{tabular}{} \end{tabular} & ✘ & ✘ & ✘ & - & EC and SC CIPPRT method is 90\% less compared to OCPI \\ \hline
2019 & [PERSON] et al. [56] & SimaPro; Eco invent
\begin{tabular}{} \\ database \\ \end{tabular} & ✘ & ✘ & ✘ & ✘ & - & Sodium borohydride reduction for nZVI synthesis emits & 30.23 kg CO\({}_{2}\) eq/kg \\  & & & & & & & - & Hydrogen gas reduction emits \\  & & & & & & & 58.56 kg CO\({}_{2}\) eq/kg \\ \hline
2020 & [PERSON] [55] & SAPL; CIPPRT; and \begin{tabular}{} \\ \end{tabular} & ✔ & ✘ & ✘ & - & \begin{tabular}{} \\ \end{tabular} & \
\begin{tabular}{} \end{tabular} &
\begin{tabular}{} \end{tabular} \\ \hline
2020 & \begin{tabular}{} \end{tabular} & \begin{tabular}{} \end{tabular} & Predict sewer \begin{tabular}{} \\ \end{tabular} & \
\begin{tabular}{} \end{tabular} & ✘ & ✘ & - & KNN model showed an 83.4\% \\  & [PERSON] [97] & pipe condition & ✘ & ✘ & ✘ & - &
\begin{tabular}{} \end{tabular} \\ \hline
2020 & [PERSON] et al. [98] & SimaPro;
\begin{tabular}{} \\ \end{tabular} & Bibliometric & ✘ & ✘ & ✘ & ✘ & - & LCSA reveals resource depletion, eutrophication, and maintenance costs as major environmental impacts in remediation projects \\  & & analysis tools & & & & & - & Multi-criteria decision analysis aids sustainability assessments. \\ \hline
2021 & [PERSON] and [PERSON] [59] & Environmental \begin{tabular}{} \\ \end{tabular} & ✘ & ✘ & ✘ & ✘ & - & Social costs increase project estimates by 20–40\% \\  & \
\begin{tabular}{} \end{tabular} &
\begin{tabular}{} \end{tabular} & ✘ & ✘ & ✘ & - & Need for standardized quantification methods \\ \hline
2022 & [PERSON] [99] & Prediction model for sewer pipes & ✘ & ✘ & ✘ & ✘ & - & Random Forest algorithm, which achieved an F1-score of 0.94 \\ \hline
2022 & [PERSON] [100] & \
\begin{tabular}{} \end{tabular} &
\begin{tabular}{} \end{tabular} & ✘ & ✘ & ✘ & - & Tree-based models (e.g., Random Forest and XGBoost) were favored \\ \hline
2023 & [PERSON] [101] & \
\begin{tabular}{} \end{tabular} &
\begin{tabular}{} \end{tabular} & ✘ & ✘ & ✘ & - & XGBoost model with hyperparameter tuning was chosen \\ \hline
2023 & [PERSON] et al. [102] & \
\begin{tabular}{} \end{tabular} &
\begin{tabular}{} \end{tabular} & ✘ & ✘ & - & Weibull analysis was chosen for its reliability in estimating failure probabilities \\ \hline \end{tabular}
\end{table} 
Table 3: _Cont._