Research On The Method Of Traffic Guidance And Diversion Of Freeway Network

Freeway network is one of the most important infrastructures in regional transportation system,wich greatly improves the connection and communication of regional passenger and freight.However,with the rapid growth of travel demands,the problem of traffic congestion on freeways is becoming worse,both in frequency and severity.When they are serious,they can spread to the adjacent roads of the expressway and cause significant impact on road networks.Traffic guidance and diversion measures are important measures to relieve traffic congestion with the road network and to equalize the traffic flow on the road network.The research on traffic guidance and diversion method for freeway networks can provide theoretical basis and technical support for traffic managers to formulate schemes of traffic guidance and diversion and construction of traffic guidance systems.It has important practical significance to reduce the impact of traffic congestion on road networks and improve the operating efficiency and safety of freeway networks.The traffic operation characteristics of freeway network are analyzed based on highway toll data and detector data,including spatial and temporal distribution of entry volume,the reliability of travel time,spatio-temporal distribution of accidents,service level of roads,and spatio-temporal distribution of cross-section volume.The results show that the distributions of the entry volumes are uneven both in time and space,and the travel time variation is high among some OD pairs.The freeways located in the main transport corridors have obvious traffic agglomeration characteristics.These characteristics provide the necessary preconditions and feasible diversion paths for traffic guidance and diversion.A traffic performance discriminant index system is constructed,and a method for dividing the freeway traffic performance state is proposed besed on this index system and divided into five levels.Based on the results of division,the traffic performance index model of freeway sections was constructed,and the traffic performance index model of the main line and the network was constructed with the weight of the vehicle travel time.Based on the Extended Kalman Filter model,combined with the traffic performance index model,a trend forecasting method for traffic performance state is proposed,and the validity of the method is validated by an example of freeway.These analyses provide discriminant standards and quantitative support for the subsequent research.The adaptability conditions for traffic guidance and diversion of freeway are put forward.The principles and conditions for the implementation of traffic guidance and diversion measures are discussed.Based on the traffic wave theory and the traffic performance index,the triggering conditions for the traffic guidance and diversion of freeway networks on the micro and macro aspect are proposed quantitatively and the corresponding decision flow is given.A method for freeway traffic guidance and diversion is proposed.A dynamic traffic assignment model with dynamic user equilibrium as the path selection principle is constructed,and an MSA algorithm with optimized weighting is presented.The scope of traffic congestion in freeway networks is analyzed and divided into three layers: point,line and surface.Based on the premise of the driver's patience for queuing time,a two-step determination method for traffic guidance and diversion region primary selection and optimization is proposed based on the vehicle travel hour variability index and the vehicle travel hour deviation.Based on node space importance,function importance,degree of circuity and collinearity,a method for classifying guidance nodes is proposed,and proposes an implementation process for traffic guidance and diversion of freeway networks.The principle of release of inducing information and publishing requirements is dicussed,and proposes two strategies for inducing information release,group induction and individual induction.The strategy of guidance information release and trucks travel stagger peak time on major holidays.It also clarifies the time and principle of this strategy and puts forward corresponding safeguard measures.Combining the operation and management of highways at provincial level dispatching centers and highway monitoring subcenters,an implementation strategy for the implementation of freeway network induced diversion is proposed,which provides effective technical support for the formulation and implementation of induced diversion schemes by road management agencies.Based on the Aimsun traffic simulation model,the method of traffic guidance and diversion of freeway networks proposed in the thesis is applied to the case.The traffic simulations are carried out on four type conditions: normal traffic performance status without traffic incident,no treatment post-traffic accident,no classification and grading of alternative guidance points,and the optimization of alternative guidance points.The simulation results are compared and analyzed.The simulation results show that the proposed traffic guidance and diversion of freeway networks has obvious effects on relieving congestion and improving the operating efficiency of the freeway network.It has important theoretical and practical significance for the formulate schemes and effect evaluation of traffic guidance and diversion method.