Development of wireless sensor network technology and its challenges in subway tunnel engineering

The structures will deteriorate with the extension of service life after the completion of civil engineering infrastructures. Structural health monitoring systems are widely adopted to monitor the behavior of structures and evaluate the safety and durability of structures. The monitoring of urban subway tunnel structures is significant and difficult due to combined effects of ground water erosion and train vibration loads, wireless sensor network(WSN) technology provide a promising method to monitor subway tunnel structures. Wireless sensor network provide advantages in cost, size, flexibility and distributed intelligence, compared to traditional wired monitoring method. However, as a emerging technology, there are some limitations for the application of WSN in subway tunnel monitoring, such as signal attenuation inside tunnel, node deployment, time synchronization, limitation of battery. The state of the art in wireless sensor network technology is reviewed, recent research and application activities on monitoring of civil infrastructures are briefly introduced. Challenges of the application of WSN in subway tunnel are analyzed and summarized, and the future research directions are discussed.