## 4 Results and Analysis
### Length of the Transition Area
Vehicle speed increased as the transition zone length increased, and the opposite was true for driving workloads. The lengths of the transition areas set up on the experimental road increased in steps of 40 m, but their impacts on vehicle speed and driving workload were non-linear. When the transition area length was 80 m, the length was lower than the theoretically calculated value. Vehicle speeds were lower than the speed limit, the speed dispersion was large, and the overspeed rate was low. There were significant differences compared to the adjacent areas and other transition area lengths, and the vehicle speed difference compared to the advance warning zone (A) was too large (>15 km/h). The driving workload was relatively high, and showed significant differences compared to the adjacent areas and other transition area lengths. Its mean, SD, higher-risk ratio, and high-risk ratio were 1.32, 1.47, 1.50, and 4.19 times higher than those of the other transition area lengths. The overall traffic safety risk was high, and the length was relatively low. When the transition area lengths were 120 m and 160 m, the length matched the theoretically calculated value. Vehicle speed was consistent with the speed limit, the speed \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Area** & **A** & **B\({}_{\text{80}}\)** & **B\({}_{\text{120}}\)**\#** & **B\({}_{\text{160}}\)**\#** & **B\({}_{\text{200}}\)** & **C \#** \\ \hline
**A** & - & 18.25 & 12.96 & 11.77 & 9.65 & - \\ \hline
**B\({}_{\text{80}}\)** & \(-\)18.25 & - & \(-\)5.29 & \(-\)6.48 & \(-\)8.60 & \(-\)5.08 \\ \hline
**B\({}_{\text{120}}\)** \# & \(-\)12.96 & 5.29 & - & \(-\)1.19 * & \(-\)3.31 & 0.21 * \\ \hline
**B\({}_{\text{160}}\)** & \(-\)11.77 & 6.48 & 1.19 * & - & \(-\)2.12 & 1.40 * \\ \hline
**B\({}_{\text{200}}\)** & \(-\)9.65 & 8.60 & 3.31 & 2.12 & - & 3.52 \\ \hline
**C** \# & - & 5.08 & \(-\)0.21 * & \(-\)1.40 * & \(-\)3.52 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Vehicle speed consistency for different transition area lengths. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Area** & **A** & **B\({}_{\text{80}}\)** & **B\({}_{\text{120}}\)** & **B\({}_{\text{160}}\)** & **B\({}_{\text{200}}\)** & **C** \\ \hline
**A** & - & \(-\)0.01132 & \(-\)0.00693 & \(-\)0.00641 & \(-\)0.00598 & - \\ \hline
**B\({}_{\text{80}}\)** & 0.01132 & - & 0.00439 & 0.00491 & 0.00534 & 0.00999 \\ \hline
**B\({}_{\text{120}}\)** & 0.00693 & \(-\)0.00439 & - & 0.00052 * & 0.00095 * & 0.00560 \\ \hline
**B\({}_{\text{160}}\)** & 0.00641 & \(-\)0.00491 & \(-\)0.00052 * & - & 0.00043 * & 0.00508 \\ \hline
**B\({}_{\text{200}}\)** & 0.00598 & \(-\)0.00534 & \(-\)0.00095 * & \(-\)0.00043 * & - & 0.00465 \\ \hline
**C** & - & \(-\)0.00999 & \(-\)0.00560 & \(-\)0.00508 & \(-\)0.00465 & - \\ \hline \hline \end{tabular}  
* Means no significant difference in driving workload (Sidak correction, 95% confidence level).  
\end{table} 
Table 7: Driving workload consistency for different transition area lengths. dispersion was low, and the overspeed rate was slightly higher than when the transition area length was 80 m. There were significant differences compared to the advance warning area (A) and other transition area lengths, with a difference of \(<\)15 km/h, and the vehicle speed was consistent with that in the activity area (C). The driving workload was relatively low, and showed significant differences compared to the adjacent areas, and when the transition area length was 80 m, it was consistent with the transition area length of 200 m. The overall traffic safety risk was relatively low, and the length was reasonable. When the transition area length was 200 m, the length was greater than the theoretically calculated value. Vehicle speed was higher than the speed limit, and the speed dispersion and the overspeed rate were high. There were significant differences compared to the advance warning zone (A) and other transition area lengths, with a difference of \(<\)15 km/h.