| In recent years,emergencies have been increasing in scope worldwide,which result in great number of people injured or dead and severe property losses,bring threats towards public safety,and is also a great challenge of reliable operation of urban transportation system.While difference exists between demand towards road network of daily situation and emergency situation,and most of transportation network design problem related research only consider the demand of daily transportation,which makes their plan may not appropriate during evacuation.Thus,analyze the characteristics of emergency evacuation transportation,and build up road network emergency reliability evaluation model and related network design can provide policy makers reliable basis when studying traffic planning.To investigate the maximum emergency evacuation demand that can be satisfied by the network designed for daily needs,it needs to analyze the physical structure of the road network,behaviors of evacuees and the emergency traffic management measures the traffic managers may take.Hence,combined with common-used emergency traffic management measures,this thesis analyzes the characteristics of traffic flow,traffic demand and network under emergency,and put out the conception and evaluation indicator of emergency reliability at first.Then,a bi-level programming model is constructed to describe the problem of interest,which up level model aims to maximum the emergency reliability and also considers the impact of applying lane reversal under emergency.The lower level model is a joint UE distribution/assignment model with capacity constraints with the consideration of congestion influence on the routes and in the shelters,describing route and shelter choices of evacuees in emergency situations.When solving the problem,the lower level model is transferred into an equivalent capacitated UE problem with multiple origins and unique destination,with a simply modification of augmenting the original network with a dummy node.To avoid falling into local optimality,genetic algorithm is used to solve the bi-level model.Next,based on the proposed transportation network emergency reliability evaluation model,the key section recognition method is constructed,and with the consideration of limited expansion cost constraint and application of lane reversal,two transportation network design model against:(1)maximizing the road network emergency reliability,(2)considering demand of daily traffic and evacuation traffic under emergency comprehensively.Algorithms are designed to find the best lane expansion and allocation scheme.At last,a real-world network is used to test the proposed models and algorithms.The numerical example demonstrates the rationality of the proposed model and feasibility of the proposed solution algorithms. |
