The New Austrian tunneling method (NATM), also known as the sequential excavation method (SEM) or sprayed concrete lining method [1](SCL), is a method of modern tunnel design and construction. This technique first gained attention in the 1960s based on the work of Ladislaus von Rabcewicz, Leopold Müller, and Franz Pacher between 1957 and 1965 in Austria. The name NATM was intended to distinguish it from the old Austrian tunnelling approach.