An Automated Surveying and Marking System for Continuous Setting-out of Tunnels.

Abstract

Setting-out is a crucial and frequently repeatedprocess in construction and civil engineering. It is carriedout by qualified operators who, making use of survey-ing stations, identify reference points to guide workersin their tasks. In this paper, we focus on the particularcase of setting-out road/train tunnels and propose a sys-tem that automatically performs the setting-out operationof the tunnel section to be perforated. The presented sys-tem, called Tunnel Continuous Setout (TCS), integratesa scanning device that surveys the excavation front and alaser projector that continuously displays the actual tun-nel section computed as the intersection between the sur-veyed terrain and the planned tunnel section. Thus, thetopographer intervention is only required for the precisepositioning of the TCS device at the beginning of eachworking stretch, which depends on the operational rangeof its components (limited to 25 meters in the current im-plementation). A prototype of the TCS system has beenemployed in a real construction site proving its benefitsand advantages with respect to the traditional setting-outtechniques