TBM Hits Construction Milestone on LA Subway Extension
A 1,000-ton, 400-ft long tunnel boring machine (TBM) named “Elsie” reached a major milestone in a $9.3-billion Los Angeles subway extension program on April 6, breaking through into a planned station about 70 ft deep.
Elsie reached the Wilshire/Fairfax subway station near the La Brea Tar Pits in the Miracle Mile area of Los Angeles. It is the second station that the design-build team led by Skanska Traylor Shea (STS) has successfully reached via tunnel as part of Section 1 of the Metro Purple Line Extension Project. STS has a $1.6-billion contract for the $2.8-billion, 4-mile, 3-station section, scheduled for completion in 2023. The other two segments, each with two stations and approximately 2.5 miles long, are also under construction.
Elsie and her twin TBM Soyeon are 22-ft-diameter pressurized, closed-face machines. The tunnels are lined with precast concrete segments that are bolted together to form a ring.
According to Metro, the geological conditions are some of the most challenging, including tar sands and methane gas.
On April 3, Metro noted that Beverly Hills City Council decided in favor of Metro’s closure request of Wilshire Boulevard to help speed up construction of one of the stations.
Regarding COVID-19, Metro has said that its contractors are holding meetings outdoors whenever possible to maintain social distancing and using a roll call instead of passing around a sign-in sheet.