Q111
In the Seattle Alaskan Way Tunnel, why was tunneling halted temporarily?
A.
Labor strike
B.
TBM hit unexpected boulder
C.
Groundwater flooding
D.
TBM encountered a steel pipe
AnswerAnswer: Option D
Solution
Answer: Option D
Solution:
Tunneling stopped when the TBM (Bertha) hit a steel pipe left from a previous investigation, damaging the cutter head and requiring major repairs.