## 4 Discussion
### Impact on Driving Speed and Acceleration/Deceleration  
The findings revealed that road markings such as RWE, RE, RWM, and RDT reduced driving speed before and during the curve, indicating that these perceptual countermeasures successfully influence driver behavior. However, there were no significant variations in driving speed between left and right turns. This suggested that the conditions decrease speed independently of the curve directions, as confirmed by [PERSON] et al. [9]; however, earlier research contradicted this [36,37]. This study also found that the average speed on curves with a small radius of 125 m is 5 km/h lower than on curves with a radius of 350 m due to the sharper geometry of the horizontal curve. It is observed that drivers tend to slow down more in sharper curves due to increased perceived risk or steering demands. In agreement with the literature [38, 39, 40], speed adjustments differ between sharp and gentle curves. For instance, drivers may decelerate more abruptly in sharper curves (see Figure 8b). Before the curve, the participants drove close to the maximum allowed speed of 70 km/h in all conditions. The posted speed limit of 70 km/h closely matches the design speed of the curve, meaning that the geometric design supports safe travel at a regulated speed. This alignment is important for interpreting driver behavior observed in the simulator study. The results indicated that they slowed down slightly upon seeing the vertical warning sign located 150 m before the curve, which is consistent with the findings of [PERSON] et al. [41]. The drivers continued to decrease their speed after passing the vertical sign while approaching the horizontal curve [42]. Among all conditions, in terms of reducing driving speed, RWM and RE exhibited similar effects; RWE was the least effective intervention, while RDT proved to be the most effective in lowering speed at the beginning of the curve. Similar effectiveness of the two different interventions may be due to the low attention paid to road markings and vertical changes, which aligns with the findings of  
Figure 11: Average lateral position across conditions and measuring points. [PERSON] et al. [43] and [PERSON] et al. [44]. The results of earlier research revealed that drivers tend to fixate their eyes and attention on the place they are heading towards. For example, when drivers drove on a straight section, they focused more on the distant horizon and less on the sides of the road [45]. However, when drivers navigated a curve, they tended to focus more on the sides of the road, particularly the edge road marking [46]. In conclusion, all road markings lower speeds compared to the control condition, with RE and RDT being the most effective, reducing speeds by about 1.4 km/h on average. This aligns with the study's aim to enhance safety through perceptual cues. Although the overall speed reduction observed with non-conventional markings might seem negligible, even small speed reductions can significantly impact road safety, particularly in high-risk areas such as horizontal curves. Additionally, the influence of the maximum speed limit (70 km/h) on driver behavior may have contributed to the observed effects, which should be considered when interpreting the results. The significant interactions show that speed reduction depends on curve sharpness, direction, and location along the curve. For example, sharper curves may see greater speed drops, and certain markings may work better at specific points (e.g., before vs. within the curve). Therefore, RE and RDT show potential as supportive measures in high-risk areas like sharp curves, where even slight reductions in speed may contribute to improved safety. In addition, drivers decelerated and accelerated more abruptly on a smaller horizontal curve (radius of 125 m) than on a larger curve (radius of 350 m). This result is consistent with established findings, confirming that road geometric features, such as curve radius, influence acceleration and deceleration behavior within the simulated environment.