The Taiwan High Speed Rail (THSR) project is the most significant infrastructure development in Taiwan, and the largest Build –Operate – Transfer (BOT) project in the world. The project is required to be completed and in operation as soon as possible. The THSR’s longest main tunnel, at 7364 m long crossing Paghuashan hills, was considered as the most critical sub-phase of the project. To ensure effective control of this critical phase, the joint venture contractor brought highly efficient construction equipment and fresh planning ideas into Taiwan. The main tunnel's excavation work was carried out using a method minimizing harmful loosening of adjacent groundmass. Engineering records reveal that the Paghuashan project was implemented successfully. The project was completed two months ahead of schedule, and even recorded the best monthly excavated length of 250 m, marking a significant milestone in the progress of the THSR project. This paper introduces the cycle of excavating and
lining technique used in constructing this key tunnel, and an the analysis of work productivity through the utilization of these automated equipment and facilities. This investigation also provides detailed insight and experience for future long tunnel construction, particularly in bidding for Design –Build (DB) contracts.