A New System for Marking off on the Face in a Tunnel

Amid the pressing need for automation and labor-saving due to the shortage of construction laborers and skilled workers, we developed a new tunnel face marking system, which automatically computed the coordinates of tunnel face center and marks the excavating plofile. Consisting of a survey instrument incorporating the latest electronics technology and a computer, the system projects the required point for tunnel excavation with laser beam onto the tunnel face. Together with high precision hardware, this system features software which serves the general purposes of various tunnels and provides easy operation by unskilled workers. This system has obtained satisfactory results, adopted for a Shinkansen tunnel. This type of technology provides valuable opportunities for improved automation of tunnel construction and other underground works.