## 2 Materials and Methods
### Dataset  
#### 2.2.1 Diagnostic Train Measurement  
A diagnostic train that makes periodic measurements in the Directorate General of Turkish State of Railways (TCDD) is the measurement technique currently used to detect movement or irregularities in the rails. The train drives along one track and sends laser pulses to collect values in a highly precise way. The model of the train is called the Roger-800 of the Mermec Group, which is shown in Figure 3. The primary method for assessing track geometry in the majority of nations is through the use of diagnostic trains equipped with inertial measurement systems. Ankara-Konya high-speed railways in Turkiye have been monitored for their condition using the Roger-800 train since August 2017.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Quality Class** & **Characterization** \\ \hline QS0 & Unsuitable Material (such as organic soil, quick clay, rock salt and gypsum) \\ QS1 & Poor Material (such as chalk, calcareous clay and clay slate, with MD \(>\) 40 and LA \(>\) 40) \\ QS2 & Average Material (like hard rock with 25 \(<\) MD \(\leq\) 40 and 30 \(<\) LA \(\leq\) 40) \\ QS3 & Good Material (like hard rock MD \(\leq\) 25 and LA \(\leq\) 30) \\ \hline \hline \end{tabular}
\end{table}
Table 1: UIC-719R soil quality classes.  
Figure 2: Geological maps: (**a**) shows the 1 st study area; (**b**) shows the 2 nd study area.  
The diagnostic train operates in both directions with a maximum speed of 120 km/h. Basic technical information about the Roger-800 is given in Table 2[38]. The geometry measuring system is placed on the front side of the car bodies, positioned between axles, as seen in Figure 4. Track geometry is measured at every 0.25 m and stored in onboard computer systems, where it is processed immediately during the ride. All measured data can also be plotted as a graphical representation and exported to external data media. The precision of the geometric measurements is 0.5 mm. One of the biggest advantages of the diagnostic train is that it can measure multiple parameters at the same time, including track geometry, gauge measurement, the condition of ballast, track videos/photos and the acceleration of bogies/car bodies with high precision. However, the diagnostic train can only observe the railway line itself, not its surroundings, and the temporal measurement frequency is relatively low, e.g., three or four times for high-speed lines and twice a year for regional lines. In addition to these limiting factors, the sensors can be adversely affected by extreme weather conditions, which can lead to noises in the measurements and, thus, misinterpretation of results. It should also be noted that there are also operating and maintenance costs, which include periodic inspections and calibrations.  
This research includes a total of nine train measurements, taken on average every three months between December 2017 and December 2019.  
The working principle of the levelling measurement sensors in the diagnostic train is similar to the principle of terrestrial levelling measurement, and here, the Inertial Measurement Unit (IMU) is used, as shown in Figure 5.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Inspection focus & Track and Catenary \\ Length/Width/Height & 22.5 m/2.85 m/4.1 m \\ Weight & about 70 t \\ Maximum drive speed & 120 km/h \\ Track gauge & Typically, 1435 mm or narrow \\  & Track measurement and inspection \\  & Catenary inspection and measurement \\ Measuring systems available: & Clearance gauge measurement \\  & Tunnel wall inspection \\  & Signaling and TLC monitoring \\ \hline \hline \end{tabular}
\end{table}
Table 2: Properties of Roger-800 diagnostic train.  
Figure 3: Roger-800 performing measurements on the Ankara–Konya high-speed railway. The image was provided by [PERSON].