Research On Emergency Dynamic Traffic Assignment Model Of Urban Road Under Disaster

Since the21st century, disaster events have occurred frequently in the world. Thedisasters in urban road networks, which bring great influence to road traffic system, givegreat losses to people’s life. They restrict the sustainable development of society andeconomy. Multiple disasters not only give warnings to the local government around theworld, but also test the emergency evacuation capacity of urban road traffic systems.The power of a city’s operation is mainly embodied in the capability oftransportation. An open road traffic environment can promote the vigor and vitality of thewhole city. It is well known that there are many influences that multiple disasters bring tothe road traffic systems. Therefore to carry out effective distribution of road network flowunder disaster traffic events, and to realize reasonable use of the maximum resources, it isnot only helpful to improve the urban traffic emergency response ability, but also canreduce casualties and property losses. So taking it for subject matter, this has veryimportant realistic meanings.According to the above cognition, it is an important key link of emergencyevacuation to make full use of the roads, city spaces and other engineering facilities torealize dynamic traffic assignment after disaster. This article is just under this kind ofsituation, through the analysis of the attributes of disaster and the influences to roadtraffic condition, we discuss the dynamic traffic assignment under urban road networkform the Road impedance function and the road intersection delay function. And weconstruct emergency dynamic traffic assignment model of urban road under disaster. Thisarticle is mainly rely on Traffic Organization Security Technology under Major Disasterconditions. The paper includes six parts:(1) Exordium. Firstly, the paper introduces the projects. On that basis, draw forth thepurpose and meaning of researching emergency dynamic traffic assignment underdisaster. Secondly, according to the solutions of current domestic and overseas’government on disaster, we make three aspects to review the research status of domesticand foreign research situation. Then on the basis of it, we co nfirm the research scope,research purpose and meanings of the paper. At last, we give the research ideas and structure framework of the paper.(2) Analysis of urban road network traffic characteristics under disasters. The paperreviews the definition of disasters. Then analyses the attributes of disasters. According todifferent division standard, disasters can be divided into different types of events.Researches the impacts to urban road traffic network. Finally, according to the needs ofthe actual research, this paper briefly introduces the related attributes of traffic survey.(3) Research on the update impedance model of urban road under disaster. Thispaper briefly introduces the network of city road impedance’s constitute. According to theclassification standard for emergencies, we confirm the grade of disasters. Then the papergives the diffusivity of disasters. Again, analyses the of common road resistance functionmodel, on this basis, updates the urban road impedance model. At last, sets up urban roadintersection signal delay function about different degree of saturation.(4) Research on emergency dynamic traffic assignment model of urban road underdisaster. First of all, the paper introduces the basic theory of dynamic traffic assignment.Secondly, this paper gives the symbols of definition and the constraint conditions whichthe emergency dynamic traffic assignment model of urban road under disaster needs.Thirdly, the paper builds emergency dynamic traffic assignment model which system isoptimal under disaster. At last, by using Hamilton method to analyze he optimal of themodel, the paper designs an algorithm for the model, according to the discrete principle.(5) Simulation and analysis of urban road network dynamic traffic assignment underdisaster. First of all, due to the lacking of practical emergency cases, the paper assumesthe contingency type and influence rank of the disaster which the article’s research needs.Secondly, the paper chooses macro TransCAD software to set up selection of the network,getting the basis network of emergency dynamic traffic assignment. Thirdly, it proceedssimulation test for the situation that assumed before, installing the related operations. Atlast, we get the results of the experiment-flow matrices and saturation matrices, thenanalyze the results that obtained from the test.(6) Summary and prospect. Comprehensive summary the contents of this paper andpoint out the limitations of the study, then put forward the direction of further research.