## 3 Results and Analysis
### Speed and Car following Characteristics
#### 3.2.2 Maximum Deceleration  
DCC max, a measure of braking response during vehicle operation, serves as a common indicator for assessing longitudinal driving safety and comfort [47,48]. Table 5 reveals significant main effects (\(p\) < 0.034) and interaction effects (\(p\) = 0.001) between CD and IV with respect to DCC max. This relationship is further visualized in Figure 7, which depicts the distribution of DCC max across different combinations of CD and IV. The legend in Figure 7c categorizes information volumes as low (5 and 7 units), medium (9 units), and high (11 and 13 units), respectively. Figure 6: Speed profiles under the combination of CD and IV. Figure 7: DCC max distribution under different CDs and IVs. The results indicate that reduced spacing and elevated IV significantly amplify the deceleration level within diversion sections, with DCC max ranging between \(-\)1.65 and \(-\)0.80 m/s2. It appears that IV carries a more profound influence on braking responses. Given a consistent spacing, DCC max displays a linear relationship with IV. Each additional two units after an IV of seven units results in approximately a 13.16% increase in DCC max, implying that drivers tend to drive more cautiously under high information loads. On the other hand, reduced CD also escalates drivers' deceleration levels. As the spacing shrinks below a CD of 700 m--identified as a turning point in the DCC max distribution--the rate of deceleration intensifies. Specifically, for every 200 m reduction in CD, DCC max experiences an average surge of 14.02%. However, this trend is not pronounced in larger spacing and GDS groups (\(p>0.085\)). According to Table 6, the interaction effects between CD and IV significantly shape the distribution of DCC max. Under varying levels of IV, the difference in DCC max between the 100 m section and GDS sections ranges from 0.213 to 0.425 m/s2. This indicates that drivers maintain relatively stable deceleration rates over different distances when signage information is low. However, with an increase in sign information, the deceleration in smaller spacing sections markedly exceeds that in the GDS scenarios. Figure 8 further shows the relative relationship between the location of maximum deceleration and DCC max, with the x-axis distance reference aligned with Figure 6. The intensity of scatter colors reveals the distribution density of samples, with darker hues denoting more concentrated maximum deceleration behavior within a particular interval. The results indicate that, when the CD is no less than 500 m, as seen in Figure 8c,d, the locations of maximum braking are widely distributed, yet primarily situated within 300 m of the transition point. When the CD falls below 300 m, the maximum deceleration position rapidly clusters within 100 m before the sign and the DCC max intensifies. This abrupt deceleration behavior could undermine driving comfort and potentially trigger backward transmission of traffic disturbance waves. Figure 8: The distribution of maximum deceleration position. Furthermore, when CD decreases and IV increases, there's an observed rise in both DH and TH. For instance, when compared to the CD of 1000 m, drivers under the CD of 100 m display an increase of 7.71% in DH and 17.96% in TH. This pattern could stem from increased driving uncertainty due to environmental switches in tunnels-interchanges, suggesting drivers adjust their behavior for safety in changing environments. Besides, IV has a significant impact on DH and TH distribution, with drivers often decelerating near signs to adjust to environmental changes. The study reveals that once the information volume exceeds seven units, each two-unit increase leads to an approximately 1.48% and 4.95% rise in DH and TH, respectively. The interaction effects in Table 6 demonstrate that in sections with small spacing, IV changes more profoundly affect CF behavior. In comparison to GDS samples, the average intergroup differences in the DH and TH of small spacing rise by 42.8% and 84.2%, respectively.