In this paper, a wireless sensor network for strain cycle monitoring on railway bridges is presented. The network implements tools such as optimized strain sensing hardware, embedded data processing, and event driven monitoring with sentinel nodes to achieve high quality data and long operation periods. A test deployment on a railway bridge demonstrated that the monitoring system performed very reliably and the quality of the recorded data met the requirements of fatigue life assessment. Although strain cycle monitoring is data intensive and expensive in terms of power consumption, the combined use of optimized strain sensing hardware, embedded data processing and event driven monitoring allows to achieve an operation life-time of several months.