Research On Emergency Traffic Route Choice Model In Emergency Conditions

In recent years, unexpected events occur frequently around the world. Such astropical cyclones in1991, Tokyo subway "sarin" nerve gas spill in1995, the SoutheastAsian financial crisis in1997,"9.11" terrorist attacks in2001, tsunami in the IndianOcean, and the earthquake caused by nuclear power plant explosion in Fukushima. Theseemergencies have caused heavy casualties and property losses. With the accelerated paceof China's urbanization process, urban construction, road traffic volume increasing, theyare dued to road traffic accidents, the major groups of petitioners, chemical, fire and otheraccidents caused by road traffic public emergencies. Bursts of strong public emergencies,and the amplification effect on the loss significantly on the social order, social function,social environment,which are caused serious damage, and impact on people's lives andthe functioning of society. The method which prevents to the timely disposal under theconditions of natural disasters and other public emergencies of major road traffic, this isof great significance to enhance emergency response capacity, ensure road traffic safety,smooth, and maintaining social stability.If we take a scientific and effective emergency measures, the disaster can stillreduce or even avoid. In this paper, we take on an appropriate emergency evacuationstrategy and set up the optimal dynamic evacuation path method under the trafficconditions before and after the disaster. This study relys on "A Disaster Under theConditions of Traffic Organization Security Technology" and "Abnormal Road TransportAbnormal State Access to Information Technology" two subjects, and the main content ofthis paper are as follows:(1) Introduction. Firstly,we introduced the subject of sources and researchedbackground of the paper. On the basis of the research status, we give a method on thechoice model which studies the traffic path under the emergency conditions. The ideasand framework of the thesis is given at the end of this chapter.(2) Topology structure model based on GIS emergency traffic network. We putforward two road network models: one is incremental updating model based on roadnetwork of the topology structure, the other one is the traffic network users balancemodel. First introduced the network topology structure of the definition and five kinds ofcommon topology structure, and they were compared. From the result of the comparison that von Neumann structure is more suitable for road network. Secondly, we construct thenetwork topology structure on the basis of the definition of the network topology. In thestorage aspects of topology structure, this paper puts forward three data model, whichwere incidence matrix, the adjacency matrix and adjacent table. By comparison, theadjacent table is more suitable for storaging road network data. For emergency situation,we have to update topology structure whichi is already built, and use XML language todescribe incremental updating process. For the traffic network users balance model,firstly we introduced the traffic network and classification. For a given the network, theshortest path problem is simple from starting point to target point. For different needs(shortest time the shortest path, etc),we need to solve different optimal path. To solve thisproblem, this paper established driving time of the shortest network model on theemergency conditions.(3) Based on improved LPA~*algorithm route choice model on the emergencyconditions. Firstly, we describe LPA~*algorithm in detail. LPA~*algorithm is a dynamic ofthe shortest path algorithm, it combines with A*algorithm and RR algorithm. Thealgorithm removes unnecessary node to reduce the search space. Like most otherdynamic methods, LPA~*algorithm defect is, it can only be reset to fixed dynamic pathfrom the starting point and the target point, but can't be satisfied with the path inquires inthe way. In order to overcome this problem, we puts forward the improved LPA~*algorithm on the emergency conditions. When there is a sudden emergency, road trafficcondition changed, the user needs to change the starting point, but the previous searchresults can still be reused. Then we need to all of the nodes to set up a new heuristic, andthen to calculate. In order to effectively access priority queue, we use binary pile, binarypile can insert and delete operation. Through the use of binary pile, all search algorithmcould increase the performance. The experimental results show that, in most cases,improved LPA~*algorithm is significantly better than A*algorithm. In the worst case, ifthe network of the weight of significant changed, the performance of improved LPA~*algorithm and the performance of A*algorithm are the same. Therefore, in most cases,improved LPA~*algorithm, which can solve the inquires of users when emergencies occurin transit. At the same time, in order to improve the performance of the LPA~*algorithm,we use a constrained ellipse, which can limit the search area.(4) Based on the parameter optimization route choice model on the emergencyconditions. In order to find the expected to minimize the cost of the road, we put forwardthe corresponding cost function. With different value, we can find the optimal solution ina limited range. But random motion is nonlinear in the emergency conditions, so we givethe improved optimization algorithm--pruning algorithm. Throuth the experiment isproved, pruning algorithm conforms to the needs of people on the emergency conditions.(5) The control strategy of intersection on the emergency conditions. Conditions on the emergency conditions, there is a need to evacuate or concentrate a large number ofpersons and goods in a relatively short time. Under this background, we demonstrated thevehicle arrive-set off balance on road basing on store-and-forward theory and focused onstudying Green ratio optimizing model aiming at traffic equalization in intersection. Themodel can limit the threshold of phase green time in safe, efficient and fair aspect. Andthe model solution is accomplished by improved F-W optimization algorithm. Finally, thevalidity of the model is verified through VISSIM traffic simulation tool with real data ofroad intersection.(6) Conclusion and prospect. This part makes a comprehensive summary, andpoints out the existing limitations of the study and the paper further research work ofprospected.