Traffic Flow Characteristics And Guidance Control Schemes For Accident Sections Of Expressway

The accident scene usually occupies one or more lanes.After a traffic accident occurs on an expressway,which not only reduces the road capacity,but also affects the traffic safety of passing vehicles,resulting in serious casualties and property losses.Based on this,in the context of the rapid development of the modern intelligent transportation industry,based on existing guidance facilities and guidance methods,through the release of reasonable induction information to achieve the control of traffic flow in the accident section,propose feasible and effective induction speed limit control scheme,for improving the safety of the accident section and optimizing the traffic conditions,has important practical significance and application value.Firstly,considering the traffic flow characteristics of the accident section and the impact of the accident on vehicle running,the traffic flow model of the three-lane expressway was constructed according to the random lane-changing and forced lane-changing behaviors of the accident section based on the cellular automata theory.The simulation of the model was carried out by Matlab to study the traffic flow characteristics of the accident section of the expressway.The results showed that the number of lane closures and traffic flow density had a great influence on the length of the vehicle queue and the dissipation of traffic congestion upstream of the accident point.The larger the number of lane closures and traffic flow density,the more serious the queue length and traffic congestion.Secondly,the external induction mode based on the Variable Message Sign(VMS)on the side of the road is studied in the intelligent high-speed environment.The influence of the visible distance on the driver when receiving induction information from VMS facilities is considered,and the early lane change behavior influenced by induction information is included in the construction of traffic flow model.At the same time,based on the uniform arrangement of VMS on the highway,an induction control scheme based on VMS facilities was proposed.Through simulation,the optimal speed limit control scheme under different traffic densities and lane closure times was obtained.The results show that in the case of a single lane closure in the accident section,if the traffic flow density is low,traffic control based on VMS facilities will lead to a "negative optimization" effect.For all traffic flow conditions in the case of two-lane closure,the implementation of traffic control can effectively improve the traffic flow safety,traffic efficiency,congestion rate,and other indicators of the accident section.Finally,the vehicle terminal guidance,another guidance mode of the traffic guidance system,is studied.The vehicle terminal guidance belongs to the vehicle guidance mode and can directly transmit the guidance information to the driver in real-time.The information transmission has the advantage of immediacy and is not affected by the location of the vehicle.Also,considering three lane-changing behaviors,a traffic flow model involving vehicle terminals in traffic guidance was established,and the optimal speed limit control scheme under various accident situations and traffic flow conditions was obtained through simulation.The results showed that,regardless of the lane closure and traffic density conditions,the on-board terminal induction control can effectively improve the safety,traffic efficiency,congestion rate,and comprehensive evaluation index of the accident section.Compared with the VMS induction mode,the vehicle-mounted induction mode has a better control effect when the control target is congestion rate or safety,especially when the control target is high traffic density and long-time lane closure.However,the control effect of the two induction modes is similar when the control target is traffic efficiency.