## 5 Conclusions  
There has been a constant increase in the number of global disasters, together with the threat that they pose to life and property. The contraflow road traffic strategy is widely used to deal with the resultant emergencies and evacuate large numbers of people from affected areas. Most previous studies on the strategy have focused on route selection, evacuation time, and evacuation volume on a macroscopic level, with only a few considering the traffic characteristics and associated moving bottlenecks on a microscopic level. To address the gap in the literature and provide emergency decision makers with better theoretical and empirical support, field experiments and Vissim simulations of the contraflow strategy were conducted in the present study. Real traffic data were collected from the  
Figure 5: Data obtained by simulation of different contraflow strategy schemes. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Truck Ratio****Traffic Rate** & **0** & **10\%** & **20\%** & **30\%** & **40\%** \\ \hline
2000 veh/h & NR & NR & NR & NR & NR \\
2500 veh/h & NR & NR & NT \(>\) NC = TL & NT \(>\) NC = TL & NT \(>\) TL \(>\) NC \\
3000 veh/h & NR & NT \(>\) NC \(>\) TL & NT \(>\) NC = TL & NT \(>\) TL \(>\) NC & NT \(>\) TL \(>\) NC \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Traffic scheme recommendation for evacuation using the contraflow strategy. Xihan Highway and used to examine the traffic characteristics (road capacity and flow speed) under both contraflow and regular conditions. It was found that the road capacity of the normal lanes under contraflow conditions was similar to that under regular conditions. However, the road capacity of the contraflow lane was lower than that of the normal lanes. This was due to the creation of fixed bottlenecks at the narrow entry and exit across the median into the contraflow lane and uneasiness of the drivers due to the unfamiliar driving environment, including the reversed traffic signs along the road. The speed variations of normal and contraflow lanes with increasing traffic volume were studied. In addition, the effect of the fixed bottlenecks on the capacity and speed of the contraflow were also analyzed, and improvement measures were suggested. To further assess the problems of the contraflow strategy, the effects of moving bottlenecks caused by coaches and trucks were examined. It was found that an increase in the coach ratio might decrease the effect of the contraflow lane, while an increase in traffic volume initially increased the moving bottleneck problem, which subsequently disappeared. Because the difference between the dynamic performances and speeds of trucks and passenger cars are much larger, the effect of the moving bottlenecks caused by trucks on the contraflow lane was further examined by Vissim simulations. Trucks were found to significantly reduce the average traffic flow speed. To address this issue, special additional schemes such as \"No Trucks\", \"No Trucks in the Contralow Lane\", and \"Truck Lane\" were proposed. Among these, the \"No Trucks\" scheme was observed to be the most effective, enabling passenger cars to move at above 60 km/h when there are alterative truck routes. When the traffic flow and truck ratio are small, the \"No Trucks in the Contralow Lane\"scheme increases the benefit of the contraflow strategy, whereas the \"Truck Lane\" scheme is better when the traffic flow and truck ratio are large. This was explained by the better road utilization enabled by the allowance for faster vehicles to overtake slower ones and the lane separation of different vehicle types. The results of this study substantially contribute to the knowledge of highway traffic characteristics when using the contraflow strategy under both regular and emergency conditions. These findings can assist decision makers in evaluating the effectiveness of contraflow lanes for mass evacuation and provide a basis for optimizing the contraflow strategy using special schemes for reducing the negative impact of moving bottlenecks.