Research On Key Issues On Urban Emergency Vehicle Preemption

Emergency in urban city is always devastating. Especially in an era when urban resources are highly concentrated and the population size is constantly expanding, emergencies but only pose tremendous threats to one’s life and property. Rather, they disrupted a society’s normal advance to a large extent. In light of emergency’s characteristics of unpredictability and rapid development, City Emergency Response Center ought to send off emergency vehicle, which is driven to where an emergency takes place and further adopts emergency rescue measure for the purpose of controlling the spreading of an accident or disaster, in the shortest time. The sooner emergency vehicle arrives, the more likely an accident or disaster can be under control, which naturally reduces losses. Therefore, the rapid transmit of emergency vehicle is viewed as the key to urban emergency rescue service. Due to the worsening of traffic congestion, emergency vehicle, in despite of its preemption conferred by law, can hardly realize its right with social vehicles standing in its way. In congested areas particularly, it is nearly impossible for emergency vehicle to move forward. The efficiency of urban emergency rescue service is, as a result, seriously affected by the delay of emergency vehicle. In this case, to select rescue route together with proper intersection signal timing scheme is of great significance in guaranteeing the preemption transmit of emergency vehicle.Previous studies fail to take the implementation of related management measures into consideration. For facilitating the transit of emergency vehicle, other vehicles in congestion could be evacuated in advance from the moment emergency vehicle departs to the moment it arrives. When it comes to the issue concerning routing, traditional methods focusing on existing state of road network state tend to neglect the preemption transmit of emergency vehicle. Employing the method of routing by predicting the road state, this paper attempts to establish an emergency vehicle routing model on the premise of the implementation of related management measures. And this model can be worked out with improved Dijkstra algorithm. As for the preemption of emergency vehicle in intersections, traditional programs only function when emergency vehicle enter intersections, which might give rise to serious situation that emergency vehicle is trapped in this place. In order to solve this problem, intersection signal timing scheme in emergency is proposed in the current paper. It ensures the evacuation of queued vehicles and the turning of green light when emergency vehicle arrives. In the end, the feasibilities of above methods are tested through examples. Under the framework of theories related to traffic flow and methods of operations research, this paper models and solves issues on the routing of emergency vehicle, and meanwhile proposes intersection signal timing scheme. Those efforts might contribute to the realization of emergency vehicle’s preemption under intelligent transportation circumstances.