| Ensuring traffic safety, improving road capacity, and reducing travel generalized cost isthe basic point of traffic control and management. The strategies of freeway control werecomprised of mainline speed limit control, access control, on-ramp control, and exit-rampcontrol. It had been confirmed that the on-ramp control was the most effective and widelyused control strategy to solve freeway congestion phenomenon. The past on-ramp controlstrategies were based on the traditional traffic flow theory and the general control principle,not related to the chaos theory. It is a very meaningful and new work to study freewayon-ramp control from the point of non-linear science and chaos control. The freeway sectionwhich had only one entrance ramp was the research object in this paper. The deep research offreeway on-ramp chaos control mechanism was done. The main work in this paper wassummarized as the following four aspects:1. The performance indices about on-ramp chaos control were compared, analysed andstudied. Only one entrance on-ramp freeway section was simulated with the symmetrictwo-lane cellular automata model. By simulation experiment, regarding to the time indices’varieties of all segments in controlled ramp of freeway and the middle ramp length restrictionvia the simulation experiment and ramp queue were analyzed and the physics effects ofon-ramp chaos control were discussed. The results show that the goal of maximal efficiencycan be realized and the equity can be primarily improved by using the Bang-Bang conditionof imposing rapidly chaos control signal and canceling appropriately chaos control signal.The middle ramp length affects the degree of realizing maximal efficiency by using on-rampcontrol in freeway. In order to obtain obvious control effect, the coordination strategy must beused with the short or long middle ramp length. In order to maximum efficiency and balanceequity, the different discharging rules of ramp users when exceeding the constraint of rampqueue length should be used combining with mainline upstream traffic volume and rampdemand.2. The research about the condition imposing ramp chaos control signal. Directingagainst the uncertainty and non-linear of the traffic system, the total time was chosen as themain evaluation index for chaos ramp control effectiveness, the mainline total travel timeand the ramp total travel time were chosen as secondary evaluation indices for chaos ramp control effectiveness. The condition of imposing freeway chaos ramp control was analyzedand studied by a large number of experimental cases. The experimental results show that“When the traffic flow was in non-chaotic state, without imposing chaos control signal isbetter than imposing chaos control signal. When the traffic flow was in chaotic state, withoutimposing chaos control signal is not better than imposing chaos control signal.3. The research about the time of imposing and canceling ramp chaos controlsignal.Based on the condition that imposing freeway chaos ramp control signal, in order toget the best time to impose and cancel the chaos control signal, obtain that making theordered state of traffic change to disordered state of traffic flow, restrain the congestion oftraffic, reduce the total travel time, and improve the road capacity, it is studied in depth thatwhen the chaos control signal was imposed and canceled.4. The research about the comparative research of the ramp chaos control and thetraditional ramp control. Freeway chaos ramp control was based on that chaos wasdistinguished and controlled, it is different from traditional freeway ramp control. Based onthis, effect comparison of chaos ramp control and traditional ramp control was done indifferent states of traffic flowing by simulation experiment in the paper, results show thatchaos ramp control is better than traditional ramp control. |
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