Due to the increasing traffic volume on the European railway network, the remaining fatigue life of existing steel bridges is a major concern. Several investigations demonstrated that supplementing the assessment with monitoring data enables to achieve more reliable remaining fatigue life estimations. In this paper, an event-driven monitoring system based on a wireless sensor network that consists of two functionally different components was designed and tested. Sentinel nodes, which were mounted on the track, were used for detecting approaching trains and alerting with alarm messages the monitoring nodes. These nodes, which were mounted on the bridge, started strain sensing and data recording after receiving the alarm message and went back to a power saving mode upon completion. An embedded data processing algorithm transformed the recorded raw data into a much smaller data set representing strain cycles. A test deployment on a railway bridge demonstrated that train detection and alarming was fast and reliable. The combination of event-driven monitoring and embedded data processing allowed to extend the battery lifetime of monitoring nodes to several months.

Event-driven monitoring policies enable to significantly reduce the power consumption of wireless sensor networks by reducing the recording period to those time intervals that provide valuable data. The resulting longer operation lifetime increase discloses fields of application that require long monitoring periods. This paper presents a structural monitoring system that uses specialized sentinel nodes for detecting possibly heavy road vehicles and for alarming monitoring nodes, which are specialized on strain sensing. Heavy vehicles are identified by estimating nearly in real time height and length of vehicles of a traffic flow by processing data recorded from low-cost ultrasonic and magnetic displacement sensors. Field tests demonstrated that while height detection is very reliable, length detection is too imprecise to discriminate with high success rates between trucks and delivery vans.

Article presents a way of providing a project management support through web based application, using Open Source solutions. First the architecture is discussed, then consequently layers of the architecture are described, additionally possible further developments are mentioned.