33 rd International Symposium on Automation and Robotics in Construction (ISARC 2016) Coupling Wireless Sensor Networks and Unmanned Aerial Vehicles in Bridge Health Monitoring Systems H. Izadi Moud a and M. Gheisari a a M.E. Rinker, Sr. School of Construction Management, University of Florida, USA E-mail: izadimoud@ufl.edu, masoud@ufl.edu Abstract Bridges are exposed to different types of damages within their lifetime. Bridge maintenance is an essential procedure that can significantly improve lifetime and serviceability of bridges. First step in bridge maintenance is inspection. Visual inspection has been traditionally the dominant method of bridge inspection. Although visual inspection is still used by several authorities to inspect bridges, it is prone to errors, due to human biased judgement. Using wireless sensor networks is a non-destructive method that can help bridge maintenance teams to monitor bridge health. Although there are many advantages associated with using wireless sensor networks in bridges, there are some downsides like battery failure and large volume of collected and transmitted data. Unmanned aerial vehicle is a new mobile robotic agent that can help wireless sensor networks to overcome some of its shortcomings. This paper explores the advantages and disadvantages of using wireless sensor networks in bridge health monitoring systems. Also the advantages of using unmanned aerial vehicles in bridge health monitoring systems are discussed. This paper would investigate the synergy between coupling unmanned aerial vehicles and wireless sensor networks in bridge health monitoring in order to overcome traditional limitations of bridge health inspection. Keywords Bridge Health Monitoring Systems; Unmanned Aerial Vehicles; UAV; Wireless Sensor Networks 1 Introduction Human-made structures are exposed to different kinds of damages. Damages may happen due to the severe structure ambient factors, e.g. weather condition, which may frequently happen to the structure or due to the less frequent factors, e.g. natural disasters, which may or may not happen to the structure during its lifetime. In order to maintain an acceptable level of service for a structure, it is necessary to monitor the health condition of the structure and take the necessary actions to maintain its health – e.g. repairing damaged parts or redesigning. Ponte Fabricio Bridge, which was made in 62 BC in Rome, and still in service, is a good illustration of the importance of the structural maintenance. It shows that a good design accompanied with good maintenance service can expand the lifetime of a structure to more than two thousand years [1]. First step in maintenance is inspection. Amongst the numerous ways to inspect structure health, visual inspection, traditionally, has been the common method. However, by having massive structures – in terms of dimensions – in the twentieth century, mostly after the Second World War, visual inspection was not able to satisfy the requirements for structure health inspection. Cabled (wired) sensors replaced the visual inspection method gradually. Nevertheless, the visual inspection is remained as a common and, most importantly, low- priced method for structure health monitoring usually in small and medium scale structures [2]. Bridges, as highly loaded structures, also need proper inspection. Researchers have investigated the use of new technologies in bridge health monitoring systems (BHMS) for more than a decade. Pines and Aktan [3] highlighted the lack of accuracy in visual inspection. A study by Federal Highway Administration revealed that around 56% of the average condition ratings by visual inspection were incorrect [3]. Oh et al. [4] noted that the majority of systems that have been used for bridge health monitoring rely on manual processes of counting the cracks, measuring cracks’ lengths and widths and using static images that have been taken from bridges. The reliability of these methods depends on inspectors experience in bridge inspection. Consequently, sensors have been used in bridge health monitoring to overcome drawbacks of visual inspections. Using sensors in structural health monitoring instead of visual inspection has brought many advantages to structural maintenance. Although sensors are more accurate than visual inspections there are a few disadvantages associated with them. Sensor networks in