Structural health monitoring for long-span bridges using wireless smart sensor network (WSSN) has drawn significant attention. The benefits of the WSSN are low-cost, time efficiency, and postprocessing- free operation. However, some drawbacks have remained with respect to implementation of WSSNs on long-span bridges, including power consumption, manual communication with the sensor network, and limitations on the hardware. In this paper, the solutions for these drawbacks are provided by an energy efficient autonomous monitoring strategy, combined with newly developed sensor boards. The elements of the autonomous monitoring strategy consist of energy efficient sleeping mode and automatic thresholdbased sensing. A tri-axial acceleration board with temperature and humidity measurements and a wind speed sensor board are utilized. To demonstrate the efficacy of this hardware/software solution, 70 Imote2s loaded with the developed software package have been deployed on the Jindo Bridge in South Korea. For further energy efficiency, several of these nodes are solar powered.