Marking a new construction milestone for the Metro Purple Line Extension project, the first Tunnel Boring Machine (TBM) has officially broken through to connect with the Wilshire/Western subway station in Koreatown.
The 1,000-ton, 400-feet long TBM named “Soyeon” burrowed through the last remaining cluster of soil 50 to 70 feet below busy Wilshire Boulevard Tuesday afternoon, June 11. The TBM is one of two TBMs to mine approximately two miles of parallel subway tunnels between the future Wilshire/La Brea Station and the existing Wilshire/Western Station.
The breakthrough marks an early triumph in the decades-long effort to extend L.A.’s subway farther west underneath Wilshire Boulevard, one of the busiest and most congested urban thoroughfares in the United States.
Soyeon was originally lowered into the ground at Metro’s Wilshire/La Brea station site in the Miracle Mile area of Wilshire last October. While advancing, the TBM burrowed about 60 feet per day. It worked five days per week, 20 hours a day.
The digging has taken eight months to reach the bulkhead — the retaining wall at the face of the Wilshire/Western subway terminus. Metro anticipated future westward subway expansion and built the bulkhead wall as part of station construction. The station originally opened in 1996.
A second TBM named “Elsie” that launched six weeks after Soyeon is also expected to break through to Wilshire/Western later in June. When done tunneling this project section, both TBMs will have mined nearly half a million cubic yards of earth — the equivalent of filling 2.3 million bathtubs with dirt.
After tunneling this first leg, both TBMs will Abe trucked back to the Wilshire/La Brea insertion point. The TBMs will then be reassembled and will then tunnel west to future station sites at Wilshire/Fairfax and Wilshire/La Cienega. The TBMs are expected to reach the end of the four-mile subway section in Beverly Hills by mid-2020.
Following the tunneling operation, Metro will focus on completing construction of its first three subway stations over the next three years. This first section of the Purple Line extension is scheduled to open in 2023.
The name Soyeon is Korean for “bright” and “beautiful” and was named after female astronaut and mechanical engineer Yi Soyeon. The name Elsie is a tribute to Elsie Eaves, the first female to be elected as a member of the American Society of Civil Engineers. Metro held a contest for local students to name the TBMs in 2018. The winning names were chosen by Marianne Gutierrez, a local Fairfax High School student.
The TBMs were manufactured in Germany by Herrenknecht AG. Metro has contracted with Skanska Traylor Shea (STS), a joint venture to design and build the first section of the project.
The $9.8-billion Metro Purple Line Extension is a nine-mile underground subway project that will extend the Metro Purple Line from its current terminus in Koreatown to Westwood/VA Hospital in West Los Angeles. Section One is expected to be completed in 2023, Section Two in 2025, and Section Three in 2027. The project budget includes financing costs.