||Smart City has become an important indicator of the regional development of major advanced countries.Smart city is provided with technology which combines the use of communication sensing technology to capture a variety of messages within the city,the analysis of the received messages and integrated city system, the serial network among things and persons ,and then the service provider to improve the quality of life, transportation, environmental protection, public safety and commercial activities.Traffic signals on the intersections may be damaged ,and the costs of their building and maintenance are considered as well. Some of the intersections can not install entity traffic signals, thereby cause a threat to the safety of road users and reduce the movement of vehicles and traffic congestion.Vehicle wireless network technology enables the communication among vehicles and Road Side Unit to exchange information. Therefore, this paper discusses the scheme of virtual traffic lights are based on vehicle wireless network technology , and its can improve traffic congestion and reduce the construction costs of traffic lights.Much virtual traffic lights scheme literature is limited to a single intersection environment. When the roads are connected to the real environment, the traffic flow will affect each other. This paper considers that the chain traffic control will improve the road users’ benefits, such as average speed.In addition, this paper explores the needs for different types of vehicles on the road and the needs to give fast passing through the intersection for emergency vehicles. To sum up, this paper proposes the Adaptive Virtual Traffic Light. When the traffic flow is light, it is according to the type of vehicles to control traffic lights. Otherwise, the virtual traffic lights control will work in chain to improve traffic congestion on heavy traffic flow.Finally, the experimental simulation shows that when the traffic flow is light, the average speed of all vehicles increases 33.1 percent, and the average speed of emergency vehicles increases 49.2%. In heavy traffic, the average speed of all vehicles Increases 36.8 percent, and the average speed of emergency vehicles increases 95.7%.|
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