The Plaka Bridge in Epirus: Ground Penetrating Radar Prospection of Surviving Parts of the Collapsed Bridge, to Provide Structural Information for Its Reconstruction

Plaka Bridge is a traditional one-arch stone bridge, built in 1866 above the waters of Aracthos river, in Epirus, Greece. The bridge was the largest one-arch stone bridge in Greece and the Balkans and one of the largest of its type in Europe. The bridge collapsed on 1 February 2015, following heavy rains in the area, the only remaining parts consisted of the western part including the western auxiliary arch, and the eastern entrance. Immediately after the disaster, the National Technical University of Athens formed a scientific expert committee which undertook in-situ assessment and provided a comprehensive report on the restoration of the Plaka Bridge. More recently, as part of the planned restoration project, ground penetration radar (GPR) was utilized to study the interior structure of the surviving western abutment of the bridge, in order to provide crucial information regarding the internal layering of the bridge, the presence of wooden elements that provided cohesion between load-bearing structural elements of the bridge and its support, as well as assess the state of preservation of the surviving parts, prior to the commencement of the bridge reconstruction. GPR revealed that potentially parts of a bridge constructed earlier than the current one are embedded within the western abutment. In addition, linear patterns corresponding to wooden elements were revealed that form a complex pattern within the surviving western part of the bridge. The information provided by GPR is crucial for the design and implementation of the appropriate restoration and rebuilding work, as it is planned that some of the original parts of the bridge will be retained in the reconstructed new bridge.