They worked in shifts, day and night, to complete the excavations in record time. Despite safety measures being practically ignored to speed up work, no casualties were reported in the building phase.[5] Because the tunnel was without angles or trenches, the usual technique for dynamite-drilling was impossible (the crew used those angles and trenches as shelter while blowing up charges just a few meters away). Instead, small cavities were excavated at regular distances to allow the workers to gain cover after igniting explosives.