Tunnel Boring Machines for Extremely Tight Radius Curves

Abstract

Tunnel Boring Machines (TBMs) that are designed to execute extremely tight radius curves provide a number of benefits for projects located in dense urban environments with a lack of shaft site availability/access or where standard tunnel alignments are not possible. This paper explains the development of articulation systems used on these specialist machines and covers the operational range of curves that can be constructed with this technology. Other features of these Tight Radius Curve TBM’s, including spoil discharge systems and backup deck designs, are also discussed along with several case histories from recent projects in Bangkok, Thailand.