Performance Analysis Of Urban Road Network Under Link Restiction Condition

Urban traffic congestion has become a concern problem for residents.How to improve traffic congestion in a timely and effective manner has always been a hot topic for scholars.Driving restriction policy is a kind of traffic management method that can change the equilibrium state of the network.At present,the research on the traffic restriction focuses on the macro-level policy planning research,or the modeling calculation with certain optimization goals,while ignoring the limitation of the road network performance.The impact of the situation has often failed to alleviate the traffic congestion and even worsening the traffic.This paper explores the characteristics of the road network layout pattern and chose grid network as the base mode,divides the road network performance into structural performance and traffic performance,using complex network theory and VISSIM simulation to analyze the difference between the performance of the road network and the effect of the traffic restriction under different link restriction modes.The main research content has the following parts:(1)Summarize the implementation experience and requirements of implementing oneway and left-prohibited traffic at home and abroad.Innovatively use the four structural parameters of T-junction,X-junction,end-to-side road,and closed block to analyze more than 40 times of line,radial,grid,and tributary road network layout patterns with instance verification.It is confirmed that four types of road networks have a certain structural distribution rule,which provides new ideas for the research of road network layout mode,Explore the characteristics of each model and select grid type network as the research object.(2)Calculating the performance index of road network structure composed of average shortest path,betweenness and node degree in complex network with the core idea of "forbidden left node judgment";Divide road network traffic performance into vehicle operation indicators and road network performance indicators represented by MFD,introduce the meaning and data acquisition methods of MFD.(3)Six kinds of traffic restrictions are respectively set for three grid road networks composed of different lengths.Analyze the changes and internal relations of the three structural performance indicators of 21 road networks.It is found that under the same link restriction range,the dense road network can maintain relatively good structural stability in different restriction modes.At the same time,the one-way traffic has greater influence on the node degree,and the left-prohibited traffic has more influence on the betweenness.It enriches the field of complex network applications and expands the content of traffic restriction research.(4)The road network simulation model creation process based on dynamic traffic assignment is elaborated,based on the network performance and traffic congested road when the base network achieves convergence,formulating the one-way traffic of the branch road,the left-prohibited traffic of the branch road,the one-way traffic of the main road,and the leftprohibited traffic of the main road in combination with the implementation conditions and principles of the traffic restriction.After multiple iterations of the restricted road network,the vehicle operation,MFD performance and congestion spatial distribution under the six traffic demand strengths are obtained.and analyze the changes of influencing factors in the inherent configuration of the road network and node degree and average shortest path in the road network structural performance.The study found that the traffic restriction mode of the leftprohibited traffic is more suitable for the grid network with more uniform demand.The MFD can judge whether the service level of the road network after the link restriction is really improved.the average shortest path in the structural performance can also be used to estimate the restriction effect of the road network,which are providing new governance ideas and early judgment methods for urban traffic managers;At the same time,the analysis finds that the design capability of intersection and the number of intersection conflict points are important factors in determining the effect of traffic restriction.optimizing it is the key to improve the service level of road network.It should be avoided that the proportion of the opposite lanes is too large or the number of lanes in the same direction is excessively increased,otherwise it will easily cause more serious congestion under high traffic demand.