In this paper are described the design and construction of a 1, 500-ft-long tunnel through mt. Baker ridge in seattle, washington. The tunnel is part of a major improvement of interstate 90. The net interior diameter of the bored portion, which is sized for vehicular traffic on two levels, is 63.5 ft. The soil is predominantly stiff clay. The project can be rated as the world's largest diameter tunnel in soft ground. construction by a stacked-drift method has resulted in minimal distortion of the liner and insignificant disturbance at the ground surface above. work was started in january 1983 and completed in may 1986. Completion of the interior roadway system is scheduled for 1988. This paper appeared in transportation research recordno. 1150, tunneling. For covering abstract see irrd no 818446.
Abstract