## 3 Results and Discussions
### Driving Speed  
To determine statistically significant speed differences between the factors at a 95% confidence level, the \(p\)-values should be below 0.05. Table 2 displays the within-subjects repeated measures ANOVA results, using the Greenhouse-Geisser correction for sphericity violations. The results show statistically significant differences for the curve radius (F(1.00, 46.00) = 130.23, \(p<0.001\), \(\eta^{2}_{p}=0.74\)), condition (F(2.90, 133.52) = 6.219, \(p<0.001\), \(\eta^{2}_{p}=0.12\)), and measuring point (F(2.14, 98.59) = 51.67, \(p<0.001\), \(\eta^{2}_{p}=0.53\)). This implies that the driving speed was significantly influenced, regardless of any other factors, for various  
Figure 5: Seven measurement points on a horizontal curve. curve radii and road marking conditions in different measuring points. Additionally, the two-way interaction effects of curve radius \(\times\) measuring point (\(F\)(2.06, 94.63) = 64.12, \(p\)! 0.001, \(\eta^{2}\)?\(p\) = 0.58) and condition \(\times\) measuring point (\(F\)(8.56, 393.65) = 4.825, \(p\)! 0.001, \(\eta^{2}\)?\(p\) = 0.10) were also significant. The significant interaction between the curve radius and measuring points indicates that the effect of the curve radius on speed varies across measurement locations. Similarly, the significant interaction between the condition and measuring points suggests that the impact of the conditions depends on the measuring point. These results highlight the location-specific influence of geometric and design factors on driving speed. In addition, the three-way interaction effect of curve direction \(\times\) condition \(\times\) measuring point (\(F\)(8.32, 382.71) = 3.09, \(p\) = 0.002, \(\eta^{2}\)?\(p\) = 0.06) being significant indicates that the combined effects of curve direction, condition, and measuring points influence speed. Also, the significant three-way interaction of curve radius \(\times\) condition \(\times\) measuring point (\(F\)(7.66, 352.14) = 2.85, \(p\) = 0.005, \(\eta^{2}\)?\(p\) = 0.06) means that the effects of measuring points on speed vary depending on the curve radius and the road marking condition. The descriptive statistics of means and pairwise comparisons for speed, adjusted using the Bonferroni correction, can be found in Table 3. Speed in all four REW, RE, RWM, and RDT conditions showed a significant difference compared to the control condition, and drivers maintained their highest speeds without special road markings. RE and RDT produced the lowest speeds and demonstrated a difference in driving speed compared to the RWE condition, suggesting that drivers slowed down more in RE and RDT than in RWE, although not statistically significant. The average speed in measuring points based on curve directions and curve radii is shown in Figure 6 to study the speed variations. The mean speed for curve directions at each measuring point is demonstrated in Figure 6a. The overall speed patterns for both directions were remarkably similar, indicating insignificant differences. The proximity of the speed diagrams for left and right curve directions supports the statistical findings reported in Table 2, highlighting the minimal effect of curve direction on driver speed behavior. More particularly, the speeds from 250 m before the curve (point 1) to the end of the beginning of the circular curve (point 4) decreased at almost the same rate for both directions. In addition, Figure 6b demonstrates the mean driving speed for different curve radii. It indicates that the driver's average speed at the beginning of the entry transition curve (point 3) with a radius of 125 m is 5 km/h lower than at a curve with a radius of