Ship crash into a river bridge – monitoring of the damaged structure

In the early morning of December 17th 2005 a ship loaded with more than 3500 tons iron ore travelling upstream the Danube River crashed into the center pier of the railway-bridge in Krems - Austria. The pier was cut off above the water surface and moved 2.17 meters upstream. The temporary stability of the damaged pier was checked by dynamic measurements. Furthermore a monitoring and alarming system based on vibration monitoring was installed on the bridge to observe the behavior of the damaged bridge for two months until the lifting of the superstructure. Because the shipping traffic under the bridge should not be interrupted, the system was designed to warn ships as well as workers on the structure early enough in advance to a collapse. The paper describes the layout and the function of the monitoring and alarming system including the real time data analysis.