‘When the New Austrian Tunnelling Method (NATM) is mentioned, it often means many different things to even experienced tunnelling engineers. The scene has more recently been complicated by new terms introduced to reflect certain aspects of NATM. Victor Romero, an associate with US-based engineering practice Jacobs Associates gives his views on NATM and its application to soft-ground tunnelling, and dispels some misconceptions about this sometimes controversial topic.

New Austrian Tunnelling Method’.‘ Sequential Excavation Method’. ‘Sprayed Concrete Lining’. Not even the tunnelling industry can give a unified name for a tunnelling method pioneered by the Austrians in the later half of the twentieth century. Furthermore, we are seeing increased use of this method in the US, particularly in soft-ground conditions. In order to better define the method, it is helpful to look at its history and use in both design and construction.