Design and calibration of a drill-guided system by laser for structural strengthening of historic bridge

Restoring the spans of a historic bridge requires installing tensors to ensure the structural and mechanical stability of the rows of stones that form the resistant body of the bridge. Once the positions where the structure-crossing tensors should be installed have been determined, the entry and exit points of each drill hole must be marked on both sides of the bridge. However, the exit point of each drill hole is not visible from the entry point, making it impossible to drill precisely. Here, we present a method based on a calibrated system that combines precision topography with laser technology. Using this method, drill holes longer than 12 m can be achieved with centimetric precision. (c) 2012 Elsevier Masson SAS. All rights reserved.