the safety of the NATM. However, the subsequent trial blamed the collapse on poor workmanship and flaws in construction management, rather than on the NATM. See also Geotechnical engineering Rock mass classification Tunnels Analysis of controlled deformation in rocks and soils References Further reading Johann Golser, The New Austrian Tunneling Method (NATM), Theoretical Background & Practical Experiences. 2nd Shotcrete conference, Easton, Pennsylvania (USA), 4-8 Oct 1976. Rock mass classification Tunnel construction