The work of the dissertation is supported in part by two national projects:"fund for one hundred young scientists of CAS" and the "fund for national distinguished young scientists".Freeway traffic stream modeling and intelligent control system are important directions in ITS domain,not only in theory but also in practice. Firstly, the general research development in the field of freeway traffic control is reviewed.After analyzing the different kinds of on-ramp control algorithms,the research direction and main content of the paper are put forward.The freeway traffic stream modeling,on-ramp control,excess off-ramp queue,coordinated ramp control and traffic control simulation platform are studied thoroughly. In ramp control,a new type of neuro-fuzzy network with the discrete output membership function is used to realize the intelligent on-ramp control algorithm.The simulation results show that this algorithm has better effect than the no-control and ALINEA algorithm in maintaining the set density and holding on the ramp queue. As to the excess off-ramp queue,the improved signal control algorithms considering off-ramp queue or traffic flow forecasting are used,which avoid the excess off-ramp queue effectively and increase the operational efficiency of highway and the whole traffic network on in the cost of little loss of the adjoin surface road. As to the coordinated on-ramp control system,a coordinated ramp control system based on multi-agent and hierarchical intelligent control structure is put forward.The structure and algorithm of execution agent,coordination agent and organization agent have been proposed.The simulation results show that the ramp control is better than no-control case and coordinated ramp control is better than the isolated ramp control,especially in balancing the travel time in all ramps and avoiding on-ramp spill-back. In the end,simulation platform for traffic control using the interface technology among TSIS,VC and Matlab are presented and used to simulate the coordinated ramp control system.This simulation platform is a powerful simulation platform utilizing the advantages of three kinds of software fully and can be used to test traffic control algorithm effectively before implementation.
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