## 3 Dataset Description and Processing
### Trajectory Extraction
5. The code extracts the following parameters: 1. [label=i]
2. TIMESTEP: The default parameter value is 0.04 s, representing the time interval between two consecutive frames. 3. LOOKBACK: Selecting data for each of the last LOOKBACK frames before a lane change event with laneChange = 1. The default value is set to 5 to ensure trajectory extraction accuracy. 4. Distance: Filtering neighboring vehicles within this range. Sensitivity analysis is performed on the threshold value to explore whether changes in its numerical value affect scenario classification. The trajectories of eight randomly selected samples are presented in Figure 3. In the context of this paper, \"location\" specifically denotes the unique 'locationId' associated with each track collection point. \"Recording\" corresponds to the'recordingId', which identifies the particular recording session from which the data was collected. Meanwhile, \"vehicle\" is represented by the 'trackId', a unique identifier for each vehicle's trajectory within the dataset. These identifiers play a pivotal role in efficiently locating and analyzing specific \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Section** & \multicolumn{2}{c}{**Merging Section I**} & \multicolumn{2}{c}{**Merging Section II**} & \multicolumn{2}{c}{**Merging Section III**} \\
**Location** & **LaneletId** & \begin{tabular}{c} **LaneletId** \\ **Length** \\ \end{tabular} & \begin{tabular}{c} **LaneletId** \\ **Length** \\ \end{tabular} & \
\begin{tabular}{c} **LaneletId** \\ **Length** \\ \end{tabular} &
\begin{tabular}{c} **LaneletId** \\ **Length** \\ \end{tabular} \\ \hline
2 & 1499/1500 & 67.56 & 1502/1503 & 119.67 & 1574 & 40.65 \\
3 & 1414/1415 & 17.90 & 1524/1527 & 168.03 & 1528 & 32.49 \\
5 & 1408/1409 & 66.54 & 1411/1412 & 132.62 & 1414 & 42.19 \\
6 & 1459/1460 & 26.62 & 1514/1463 & 192.32 & 1467 & 27.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Merging section relationship sequence laneletID list. Figure 2: The framework to process trajectory based on Lanelet2: a case study with location 2.  
vehicle trajectories. The 'latlancenteroffset' value undergoes a transition from \(+2\) to \(-2\) in frames where laneChange = 1. This indicates that the vehicle's center point has shifted from its original lane to the target lane. In subplot (a), the vehicle promptly transitions to the inner lane upon merging onto the mainline, resulting in two abrupt shifts in its 'latLaneCenterOffset' value from \(+2\) to \(-2\). As shown in Figure 3a, this merging trajectory demonstrates two distinct lane-changing events. The first 100 frames exhibit a preliminary lane change, as evidenced by lateral vehicle position oscillations centered around \(-0.5\) m. Between frames 100 and 115, the vehicle's lateral motion becomes increasingly pronounced, signifying the commencement of the initial lane changing. By frame 115, the vehicle successfully completes its first lane change, transitions into the new lane, and initiates the second lane change. The slope of lateral deviation during the second lane change is steeper than that of the first one, resulting in a shorter completion time for this subsequent maneuver. After successfully executing these two lane-changing maneuvers, the vehicle maintains a smooth trajectory in the center of the roadway. At the onset of merging, as illustrated in Figure 3a,c-h, the initial positions of the merging trajectories are all slightly offset towards the outer side of the road center. In Figure 3b; however, the trajectory initiates the merging process with an initial position slightly shifted towards the inner side of its respective lane center. Upon completion of merging, even in Figure 3b, there is a noticeable shift towards positioning on the outer side of its corresponding lane center.