Immediately after the TBM passed the planned obstacle, it hit an unexpected obstacle again, so it was difficult to judge whether it was completely removed.
Careful cutting was required due to curved construction and the limited capacity of the telescopic jack due to small pipe diameter.
Although the progress was 8 mm / day, we were able to cut the obstacles safely and complete within the construction period.
In order to reach the special manhole, all the TBM had to be cut and recovered, and it was quite difficult to cut the sturdy cutter head.