Braess' Paradox Phenomenon of Congested Traffic Networks

In the congested traffic networks,the link congestion is related to the flow on this link,as well as to that on other links.This paper investigates the properties of Braess' paradox and whether the adding link makes sense under the system optimal in the congested traffic networks.Using the user equilibrium(UE) and system optimal(SO),it gives the explicit ranges of the total demand that the Braess' paradox occurs and the adding link makes sense under SO,respectively.In addition,we investigate the influence of other links on the probability that the paradox occurs and the adding link works under SO,subsequently,we discuss the influence of other links on the difference between the total congestion under UE and that under SO.The results show the probability that the paradox occurs and the adding link works under SO,the difference of total congestion under two assignment methods are both influenced by the extent on other links,which widens theoretical ideas for the assignment of the urban transportation networks.