| As the backbone of the city,the urban road network plays a vital role in the normal operation.The improvement of the road network resilience is of great significance to the construction of a resilient city.In order to analyze the operational stability with the external disturbances,three main respects are studied.Firstly,this thesis analyzes the influencing factors of road network resilience and the impact of traffic flow assignment model on resilience quantification.To begin with,the urban road traffic network resilience and its related concepts are clarified.The thesis argues that road network resilience is a procedural concept that can comprehensively measure the road network’s ability to resist and recover from disturbances.Furthermore,the influencing factors of road network resilience are classified from the perspective of supply and demand.The positive and negative correlations between thirteen factors and road network resilience are identified.Afterwards,the decision laboratory analysis method is used to analyze the impact of road network topology,traffic flow and other attributes on road network resilience.The results show that the five factors with the largest centrality of resilience influencing factors are network capacity,traffic flows at intersections,traffic accidents,service level of road sections and solutions after disturbance.Last but not least,the impact of different traffic flow assignment models on the assessment of road network resilience is analyzed.The traditional user equilibrium model is difficult to observe the time-varying process of road network flows under disturbance,especially the duration of disturbance.Fortunately,the day-to-day traffic flow assignment model provides a research basis for the quantification of road network resilience.Secondly,the thesis proposes a road network dynamic comprehensive resilience quantification method and a road segment importance index for road network resilience improvement.First of all,the commonly used road network performance metrics are sorted from two aspects of network topology and network function,including road network density,road network topology efficiency,road network accessibility and road network traffic efficiency.At the same time,three commonly used quantitative indicators of system resilience in the literature are summarized and compared,including "resilience triangle area","performance recovery ratio" and "cumulative performance recovery area ratio".Among them,the third indicator can comprehensively evaluate the average cumulative performance of the system in the life cycle of the disturbance event.Next,the structural and functional resilience of the road network is quantified in terms of the road network topological efficiency and road network accessibility,respectively.On this basis,the functional resilience and structural resilience of the road network are integrated,and a quantitative method for the comprehensive resilience of the road network is proposed.The comprehensive resilience can cover the whole process of road network performance degradation and recovery under disturbance events.Furthermore,a road section importance analysis index for road network toughness is proposed,and this index is of great significance for formulating the road section repair sequence plan.The quantitative results of road network toughness under three different disturbance intensity scenarios are compared through a case study.The results of the case study verify the effectiveness of the proposed road network comprehensive resilience quantification method.This research provides technical support for the formulation of road network resilience improvement strategies.Finally,the thesis proposes a reversible lane design model for road network resilience improvement.To begin with,the assumptions of the road network resilience optimization model are given,and the feasibility of using reversible lanes to improve road network resilience is theoretically analyzed.Next,four setting conditions for reversible lanes on the road network and two calculation methods for the capacity of reversible lanes are determined.Further,the objective function of road network comprehensive resilience optimization based on reversible lane is designed.At the same time,the dynamic changes of traffic flow in different stages are considered,and then the flow assignment of urban road network under disturbance events is determined.At last,genetic algorithm is used to solve the road network recovery strategy based on reversible lanes after disturbance.The feasibility and effectiveness of the reversible lane design model for improving road network resilience are verified by a case study.In the example,the road network resilience values of the artificial restoration scheme and the reversible lane scheme are compared in two different scenarios.The network resilience growth rate indicator is used to quantify the degree of resilience improvement.The results show that in the two scenarios,compared with the manual restoration scheme,the road network resilience under the reversible lane scheme is improved by 10.98% and 11.21%,respectively.This study provides a new solution for reducing the negative impact of external disturbances on urban road networks. |
PDF Full Text Request