The Variable Speed Limits Of Freeway Work Zone

Because of the continuous development of society,while the number of motor vehicles is also increasing.In this case,the early completion of the highway traffic facilities and the gradual emergence of the damage to the road conditions of different situations.Based on this situation,most of the existing old highway has been unable to meet the increasing traffic demand.Therefore,the part of the highway around the section has entered a strong maintenance,maintenance and expansion period speed limit has been the point of social concern.The traditional strategy speed limit is not the only solution,it also can not alleviate the congestion problem of peak period in freeway work zone effectively.So this paper put forward the strategy of variable speed limit on freeway work zone,considering four-lane as research object.Firtly,classified four typical work zone on the freeway: half closed work zone,the closed one-way inner lane work zone,the closed one-way outer lane work zone,the closed shoulder lane work zone.Secondly,Then classified the form of construction work of four-lanes,on the basis of this,And the selection of the data extraction point of the road is relatively half closed construction work zone for the research object.Through the analysis of three aspects of traffic composition,vehicle speed distribution and time headway,the traffic characteristics of freeway work zone are summarized.When through this kind work zone,vehicles should enter the warning area to exit the termination region will experience a slowdown,combined mandatory,the distribution of the traffic flow,traffic flow stability stage several processes.shifted negative exponential distribution,concerning the U-Q model in the freeway work zone.Using the ideas of multi-objective optimization,the paper brought forward the speed limit method based on economy,safety and operation efficiency.By mathematics modeling and regression analysis,the time-cost function,the cost of fuel consumption function and the cost of accident severity function were established.The fuel consumption cost considers such as road grade and capacity tonnage;the time-cost function considers the delay in work zone.Then,considering the correlation coefficient of driver compliance rate and visibility of freeway,the fiducial value of the optimal speed limit in freeway work zone will be given.Finally,based on the traffic simulation software VISSIM,and combined with the actual situation of the parameters in the model calibration,parameters of the calibration reference to use the four lane highway half closed work zone of the lane traffic characteristics and traffic survey data,the simulation platform of freeway four-lane half closed lane is built.Simulation results show that in at the beginning of warning area fixed speed and variable speed,average speed difference,in the buffer area at the beginning,in traffic large variable speed limit control,traffic flow becomes more stable,queuing phenomenon rarely,and fixed speed conditions at the confluence of the vehicle queuing phenomenon is serious.For generalized cost,comparison between variable speed limit and fixed speed limit shows that generalized cost can be downed 16.47%,so the research of variable speed control strategies for reducing the work area of the generalized cost,improve operation efficiency and safety is effective.