Traffic Flow Management using Wireless Sensor Networks
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Joined: Sep 2010
22-12-2010, 05:14 PM
Ahmed Sabith. P
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The emerging field of wireless sensor networks combines sensing, computation, and communication into a single tiny device. A wireless sensor network (WSN) consists of spatially distributed autonomous sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants. The developments of wireless sensor networks was motivated by military applications such as battlefield surveillance and are now used in many industrial and civilian application areas, including industrial process monitoring and control, machine health monitoring, environment and habitat monitoring, healthcare applications, home automation, and traffic control. We propose a novel decentralized traffic light control using wireless sensor network. The system architecture is classified into three layers; the wireless sensor network, the localized traffic flow model policy, and the higher level coordination of the traffic lights agents. The wireless sensors are deployed on the lanes going in and out the intersection. These sensors detect vehicles’ number, speed, etc. and send their data to the nearest Intersection Control Agent (ICA) which determines the flow model of the intersection depending on sensors’ data (e.g., number of vehicles approaching a specific intersection). Our main contribution is the real-time adaptive control of the traffic lights.
Our aim is to maximize the flow of vehicles and reduce the waiting time while maintaining fairness among the other traffic lights. Each traffic light controlled intersection has an intersection control agent that collects information from the sensor nodes. An intersection control agent manages its intersection by controlling its traffic lights. Multiple intersection agents can exchange information among themselves to control a wider area. Tremendous amount of time and power is wasted due to a green traffic light with no cars passing on its lane. We envision a smart road system were the total trip time is minimum due to minimizing the average waiting time on traffic lights. In addition to minimizing the average traffic waiting time, we would like to see a road system which can optimize the traffic flow by utilizing the free roads.
Our system consists, mainly, of the wireless sensor network and the intersection control agents. The wireless sensor network composed of group of nodes, each comprising one or more sensors, a processor, a radio and a battery. They generate traffic information such as number of cars, speed and length of the vehicles, based on processing of the sensor data. The information is then sent to the nearest intersection control agent over the radio. The intersection control agent collects the information from the sensor nodes to analyze traffic conditions and take actions such as adjusting the traffic light durations or exchanging information with other intersection agents for better optimization of traffic flow. In the field of Multi-agent Systems (MAS), controlling intersections is studied with intelligent system on mind. Using wireless sensor network along with intelligent transportation system is still in its preliminary stage. To compete with current technologies, however, the data provided by the system must be accurate, delivered to the traffic intersection agents within a certain time for real-time applications, and the lifetime of the system must be on the order of several years.
Many solutions were proposed to solve the traffic jam. Most conventional traffic surveillance systems use intrusive sensors, including inductive loop detectors, micro-loop probes, and pneumatic road tubes. However, these sensors disrupt traffic during installation and repair, which leads to a high cost installation and maintenance. In addition, over the ground sensors like videos, radars, and ultrasonic were used. These systems are also high cost and their accuracy depends on environment condition.
We present a real-time adaptive system based on wireless sensors that has the potential to establish a new era of traffic control and surveillance because of its low cost and potential for large scale deployment. To replace the costly and high maintenance classic traffic surveillance such as inductive loops, a traffic surveillance technology system based on wireless sensors is used. Their system is deployed in freeways and at intersections for traffic measurements such as vehicle count, occupancy, speed, and vehicle classification which can’t be obtained from standard inductive loops. The experiments in shows that deploying wireless sensor network for traffic monitoring provides %99 of detection rate in real time.
Some deeper problems need a further research. For example,
The intersection units in the same city form a huge network, which can be used to transfer traffic information. What challenges will we meet in a large scale of network?
Vehicle unit can only transfer dynamic information of a vehicle up to now. If we write some solid information of this vehicle, such as vehicle type, license ID, it will become an electronic tag, which can be used in multiple applications in transportation system, such as ETC (electronic Toll Collection), Parking Management and so on.
After vehicle unit being installed on most vehicles, the traffic information can exchange among vehicles, that is, the roadside unit is not necessary. Wireless sensor networks offer a promising platform for traffic monitoring that can compete with current technology in accuracy and lifetime. We have built a prototype of the sensor node for traffic surveillance. More intersection flow policy need to be investigated for the intersection agent to be able to decide the best flow policy depending on information received from the sensor network