A 1.3 km long vehicular tunnel, Sentosa Gateway Tunnel, was proposed to connect outbound traffic from Sentosa Island directly to major roads to cope with growing traffic in the area. Due to the presence of existing buildings in close proximity and carriageways that could not be diverted, a trenchless construction method known as pipe roof method is adopted for the construction of parts of the Sentosa Gateway Tunnel instead of the conventional cut and cover method. This paper presents the design considerations made and the challenges encountered during the construction of the two-lane piped box tunnel. Finite element analysis is conducted prior to the construction of the vehicular tunnel. The settlement of the pipe roof measured during the mined excavation is discussed and compared with the predicted settlements obtained from finite element analysis.
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