The TNPS method, one of the important construction methods in TBM sites, is a method that uses a protection shield to simultaneously perform TBM pilot excavation and rear NATM (cross-section expansion), and is a method with excellent constructability and stability.

Recently, when applying NATM blasting in urban areas, various complaints and accidents due to noise and vibration have increased, increasing social indirect costs. The TNPS method is a method that can significantly reduce blasting vibration and minimize dust and noise during expansion due to the free surface effect of the TBM pilot tunnel diameter.

As an advantage of the method, the method of performing NATM expansion, a blasting method, after completing TBM pilot excavation was used in the past, but by performing TBM pilot excavation and NATM blasting (cross-section expansion) simultaneously, the construction period and construction cost can be greatly reduced. In addition, the ground of the front section to be blasted was not accurately identified, but the optimal blasting pattern was applied and excavation safety was increased by visually confirming the ground conditions according to TBM excavation. The free surface effect of the TBM pre-tunnel significantly improves safety and reduces vibration and noise during blasting, and the application of protective shields and protective gear protects TBM auxiliary equipment during blasting, and the application of explosion-proof pressure shields ensures the safety of TBM machine operators during blasting. Expectations for this include the creation of a new market for urban tunnels, where most domestic NATM methods are applied, and the establishment of a foundation for the activation of eco-friendly and economical tunnel construction as a field of convergence technology between construction and machinery industries.