Study On Strategies Of Inputting Coordinated Control Signal For Freeway Based On Cellular Automaton Model

Ramp control and mainline control are the typical devices that enhance trafficefficiency, suppresses traffic jams, ensure freeway safety for the continuous traffic flowroad, i.e., freeway and city expressway. Considering the rapid development of intelligenttransportation systems and the Internet of things as well as the automation andeconomization of information collection, issuance, and implementation, coordinatedcontrol integrating ramp control and variable speed limits will become a main strategy ofmanagement and control for the continuous traffic flow road. Although the validities hasbeen proved, these theories and methods do not relate to traffic flow nonlinear, given thatthese approaches were proposed from the angle of normal traffic control and management.The research aspects focus on the selecting of control models and the identification ofcontroller parameters. However, these theories and methods do not relate to the studies ofinputting coordinated control signal condition on a freeway, given that these approacheswere proposed only by signal control method, e.g., ramp control and mainline control.Based on this, the strategies problem of inputting coordinated control signal on a freewaywas studied. The main work in this paper could be summarized as the following aspects:(1) Based on the symmetric two-lane Nagel-Schreckenberg (STNS) model, a cellularautomaton model of coordinated control section on freeway with only one on-rampsegment and a variable speed limits mainline segment was established with the actualfreeway traffic operation rules. It provided a basic model or a basic platform to study thestrategies of inputting coordinated control signal for freeway. By using the basic tool, wecan do the studies of traffic management, traffic control, programming and design, trafficsafe for freeway.(2) The traffic flow characteristics of the studied object were discussed via thesimulation experiments by using the different control strategies. The impact effectsincluding actual road capacity and traffic flow were analyzed under different traffic states,ramp demand and mainline demand by inputting no control signal, only inputting on-rampcontrol signal, only inputting variable speed limits signal, inputting speed limits signal andramp metering signal. The results of the examples show that the applicability ofcoordinated control as a main traffic management tool is better than that of other controlmethods, the traffic jams phenomena can be suppressed and the goal of achieving largest road capacity and decreasing the passing time of vehicles can be realized by using thecoordinated speed limits and ramp metering control method under different traffic demand.(3) The effects of traffic flow characteristics for the studied object were discussed viathe simulation experiments by using the optimal inputting control signals, where the trafficdemand varied. The comparison were analyzed among inputting no control signal, onlyinputting on-ramp control signal, only inputting variable speed limits signal, inputtingspeed limits signal and ramp metering signal. The results of the examples show that thebest control signal can be input and the goal of achieving the best control effect, enhancingthe largest road capacity and improving traffic states of roads can be realized by using theoptimal coordinated control phases diagram under different traffic demand.