Abstract:

This paper aimed to safely and effectively evacuate the expressway network congestion caused by emergency events and to evaluate the effectiveness of different emergency evacuation measures. Firstly, the propagation and dissipation law of expressway network congestion under emergency events were analysed, and the HNAC-FD dissipation calculation model was established. Secondly, through evacuation case traffic data, the effect of different interventions on the speed of traffic flow was simulated by Vissim, and the traffic flow state of the expressway network section was obtained based on the Logistic speed-density model. Finally, according to the case of expressway network emergencies, different intervention measures were designed, and the congestion dissipation time was calculated by the HNAC-FD model. The effectiveness of different measures was evaluated from the event impact dissipation time and the average travel time of the vehicles in the congested queue through case numerical calculations. The results show that the intervention measures delay the dissipation of the event impact, but improve the speed of evacuating traffic flow and reduce the average travel time of the congested queue. The evacuation effect of the combined measures is not significantly better than that of the single one, and the reversible lane evacuation works best.

Key words: highway node acceptance capacity (HNAC), fundamental diagram(FD) model, expressway network, emergency evacuation measures, evaluate effectiveness, emergency events