Research On Variable Speed ​​Control Of Expressway Under Unfavorable Weather

In this paper, through the analysis of the formation mechanism and influence factors of freeway accidents, the freeway stretch properties defined as special sections and general sections, as the foundation of the further divided management unit, the road friction coefficient and visibility as the variable parameters of adverse weather.The freeway administrative unit segmentation abide by the principle of adjacent sections mutual independence and seamless connectivity. Division method is divided into four levels:the first three levels will gradually divided freeway smallest control unit is the foundation of control model and field equipment layout; the fourth level after the initial speed limit value obtained by the model, according to the speed limit value standard and minimum speed limit section length adjustment of the speed limit value, combination that do not satisfy the length request the sub-sections merged in accordance with principles to form a new unit for final output speed limit values.Adverse weather freeway variable speed limits control model is divided into two sections: security distance speed limit control model and density contrast speed limit control model for freeway management unit of sub-sections as the basic control unit. Security distance speed limit control model with frictional coefficient and visibility as variable parameters, obtains the speed limit value. Density contrast speed limit control model in each sub-sections actual density as parameters to determine the control density, then calculated the speed limit value equal proportional. Finally, according to the fourth division of freeway management unit level requirements are given six steps to determine the of the speed limit value.In this paper, kunshi freeway of26km sections as the research object, divide management unit and use the model to determine the speed limit value, use TransModeler simulation software for simulation analysis, simulation results indicate that the control method has obvious effect and feasibility.