Observations of the behavior of the classic steel railway bridge structure

The authors' interest was to preserve the classic steel railway bridge structure on the Odra River in Opole (Poland) under service loads. The bridge was built in 1884. The current form of the bridge comes from the modernization in 1927-28. In the coming years, its further modernization is planned. Modernization is to adapt the facility to the requirements of modern railway transport. The author's team used a wide range of measurement techniques and geodetic instruments. Hybrid measurement techniques in the fusion sensors philosophy were the key activity in registering the behavior of structures. The major measurement technique used in subsequent sessions is terrestrial laser scanning (TLS) using Trimble scanner. Scanning measurements were verified by total station with an angular accuracy of 1" and accuracy of distance 1 mm. Additionally, flat photogrammetry and laser rangefinder (DISTO) were used. An attempt was made to register deflections of the bridge spans using scanning techniques, with so much significant slowdown of the traffic speed of trains that the scanner could cover the entire span during the passage of the trains. Based on wide experience from photogrammetric bridges measurements that complemented these measurement techniques, the accuracy obtained was compared. At the same time, the oversized number of the documented observations of the bridge's behavior is the background to the planned extensive modernization. The subsequent measurement cycles planned after it should give an interesting comparative material confronting the historical construction solutions of the 1920s with the proposals of modern design offices having an IT computing environment.