# Preventive Maintenance Decision-Making Optimization Method for Airport Runway Composite Pavements
## 3 Results and Discussion  
### Performance Deterioration of Runway Composite Pavement Regions  
This study surveyed five typical airports in China with composite pavements. Table 1 presents their structural and traffic conditions. In Table 1, CZX represents Changzhou Benniu Airport, DLC represents Dalian Zhouzishui Airport, TAO represents Qingdao Liuting Airport, XMN represents Xiamen Gaoqi Airport, and SHA represents Shanghai Hongqiao Airport according to International Air Transport Association (IATA) codes. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Airport** & **Airport Region** & **Year of AC** & **Thickness of AC Overlay** & **Thickness of PCC Pavement (cm)** & \(h_{e}\) (cm)** & **Years of Traffic** & _ESAL_ \\  & **Code** & **Aircraft Region** & **Overlay** & **(cm)** & **(cm)** & **Investigated** & _(day)_ \\ \hline \multirow{4}{*}{CZX} & Middle runway & \multirow{4}{*}{2013} & SMA-13: 5 & \multirow{4}{*}{42} & \multirow{4}{*}{39.89} & \multirow{4}{*}{2013–2017} & \multirow{4}{*}{31} \\ \cline{3-4} \cline{6-6}  & & & & & & & \\ \cline{3-4} \cline{6-6}  & \multirow{2}{*}{Taxiway} & & SMA-13: 5 & \multirow{2}{*}{56} & \multirow{2}{*}{51.58} & \multirow{2}{*}{8} \\ \cline{3-4} \cline{6-6}  & & & & & & \\ \hline \multirow{4}{*}{DLC} & Middle runway & \multirow{4}{*}{2005} & SMA-16: 6 & \multirow{4}{*}{32} & \multirow{4}{*}{34.11} & \multirow{4}{*}{93} \\ \cline{3-4} \cline{6-6}  & & & & & & \\ \cline{3-4} \cline{6-6}  & \multirow{2}{*}{Terminal runway} & & SMA-16: 6 & \multirow{2}{*}{37} & \multirow{2}{*}{35.95} & \multirow{2}{*}{2007–2011} & \multirow{2}{*}{47} \\ \cline{3-4} \cline{6-6}  & & & & & & \\ \cline{3-4} \cline{6-6}  & \multirow{2}{*}{Taxiway} & & SMA-16: 6 & \multirow{2}{*}{32} & \multirow{2}{*}{34.11} & \multirow{2}{*}{19} \\ \cline{3-4} \cline{6-6}  & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Structural and traffic conditions of the investigated airports. Figure 3: The median approach algorithm of the optimal solution. Figure 4 plots the _PCI_ curves of different regions in the five investigated airports. The _PCI_ data were collected manually on-site every four years. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Airport** & \multirow{2}{*}{**Airport Region**} & **Year of AC** & **Thickness of AC Overlay** & **Thickness of PCC Pavement** & \(h_{e}\) & **Years of Traffic** & _ESAL_ \\
**Code** & & **Overlay** & **(cm)** & **(cm)** & **(cm)** & **Investigated** & **(/day)** \\ \hline \multirow{4}{*}{TAO} & Middle runway & & SMA-16: 6 & \multirow{4}{*}{32} & \multirow{4}{*}{2013-2017} & \multirow{4}{*}{160} \\  & Middle runway & & AC-20: 7 & & & & 320 \\ \cline{2-8}  & Terminal runway & & SMA-16: 6 & \multirow{4}{*}{34} & \multirow{4}{*}{34.42} & \multirow{4}{*}{2013-2017} & \multirow{4}{*}{160} \\ \cline{2-8}  & Terminal runway & & SMA-16: 6 & \multirow{4}{*}{34} & \multirow{4}{*}{34.42} & \multirow{4}{*}{54} \\ \cline{2-8}  & Taxiway & & SMA-16: 6 & \multirow{4}{*}{30} & \multirow{4}{*}{32.95} & \multirow{4}{*}{135} \\ \hline \multirow{4}{*}{XMN} & Middle runway & & SMA-16: 6 & \multirow{4}{*}{30} & \multirow{4}{*}{32.11} & \multirow{4}{*}{2011-2015} & \multirow{4}{*}{68} \\ \cline{2-8}  & Terminal runway & & SMA-20: 14 & & & & \\ \cline{2-8}  & Taxiway & & SMA-16: 6 & \multirow{4}{*}{33} & \multirow{4}{*}{31.26} & \multirow{4}{*}{27} \\ \cline{2-8}  & Middle runway & & SMA-16: 7 & & & & \\ \cline{2-8}  & & SMA-16: 6 & \multirow{4}{*}{38} & \multirow{4}{*}{44.79} & \multirow{4}{*}{357} \\ \cline{2-8}  & Terminal runway & & SMA-13: 5 & & & & \\ \cline{2-8}  & & CA-16: 7 & \multirow{4}{*}{31} & \multirow{4}{*}{40.15} & \multirow{4}{*}{179} \\ \cline{2-8}  & Middle runway & & SMA-16: 6 & \multirow{4}{*}{38} & \multirow{4}{*}{44.79} & \multirow{4}{*}{357} \\ \cline{2-8}  & & CA-20: 19 & & & & \\ \cline{2-8}  & & 2011 & SMA-13: 5 & & & & \\ \cline{2-8}  & Terminal runway & & SMA-16: 7 & \multirow{4}{*}{31} & \multirow{4}{*}{40.15} & \multirow{4}{*}{179} \\ \cline{2-8}  & & CA-20: 19 & & & & & \\ \hline \hline \end{tabular}
\end{table}