## 4 Discussion
### Impact on Lateral Position  
Curve direction, radius, road markings (condition), and measuring points significantly influence lateral position, and the direction of the curve affects the lateral position, which is in agreement with findings from [PERSON] et al. [47]. Drivers position their vehicles differently in left versus right curves, possibly due to differences in visibility, steering demands, or driver behavior. In addition, the sharpness of the curve significantly impacts the lateral position. Sharper curves may require more precise steering, leading to distinct positioning compared to gentler curves. On the other hand, the type of road marking significantly influences lateral position, which is in line with the available literature [48]. Different markings likely guide drivers' perception and lane-keeping behavior in unique ways. The lateral position varies considerably depending on where it is measured along the curve (e.g., before, start, middle, or end). This suggests drivers adjust their position as they progress through the curve. Considering the two-way interactions, the effect of curve direction on lateral position depends on the curve radius. For example, the difference between left and right curves might be more considerable in sharper versus gentler, possibly due to increased steering difficulty. However, the effect of road markings on lateral position is consistent across left and right curves, meaning markings work similarly regardless of curve direction. In addition, specific markings may be more effective in sharper or gentler curves, suggesting that marking design should consider curve sharpness. The results also demonstrate that lateral position changes at different points along the curve depending on direction and radius. This suggests complex adjustments in driver behavior based on curve characteristics. The lateral movement results showed that 150 m before the curve, participants deviated toward the centerline of the road, regardless of the conditions. This behavior was attributed to participants perceiving vertical warning signs as obstacles near the road, prompting the drivers to move toward the centerline before returning to their initial position at the start of the curve. During the horizontal curve, drivers maintained a consistent lateral position, about 2 m from the centerline in the control condition. However, the RWE treatment led vehicles to move closer to the centerline throughout the entire curve, reaching a maximum lateral position of 1.92 m at the end of the circular curve. In addition, the RE treatments did not significantly alter the initial lateral position, indicating a consistent proximity to the centerline, ranging between 1.90 m and 1.98 m.  
The RWM treatment, on the other hand, caused lateral movement throughout the entire curve closer to the edge of the road while reaching its furthest position of 2.12 m from the centerline at the end of the circular curve. Although movement closer to the edge of the road increases the risks of more run-off-road crashes, the RWM treatment simultaneously caused a speed reduction compared to the control condition throughout the entire curve. Moreover, moving closer to the edge reduces the risk of head-on collisions with vehicles coming from the opposite direction. Therefore, the lateral position to the edge caused by the RWM treatment can be evaluated as a safe consequence. Compared with a similar study [8], [PERSON] highlighted that vehicles tended to move closer to the edge of the road marking due to the implemented red median, which aligned with the results of our study. The results of this study and the literature [5; 48] show that some marking treatments, when placed in the median, led to drivers positioning themselves farther from the centerline. In contrast, edge markings caused drivers to move closer to the centerline. This behavior suggests that drivers avoid markings, whether positioned at the median or edge [49].