In a construction milestone for the Metro Purple Line extension project, the Los Angeles County Metropolitan Transportation Authority announced Wednesday that a tunnel boring machine has broken through to connect with the Wilshire/Western subway station in Koreatown.
“Our last (tunnel boring machines) at Wilshire/Western were powered down over 23 years ago, so we are definitely going `back to the future’ in our modern-day mission to extend this subway,” said county Supervisor and Metro Board Chair Sheila Kuehl, referring to a decades-long effort to extend the Purple Line farther west underneath Wilshire Boulevard.
“I’m glad that this enormously complex operation has gone off without a hitch,” she added. “It’s a testament to the ways in which Metro and its contractors meticulously plan and execute their tunneling work.”
The 1,000-ton, 400-foot-long TBM, named “Soyeon,” burrowed through the last remaining cluster of soil 50 to 70 feet below Wilshire on Tuesday afternoon. It’s one of two TBMs to mine about two miles of parallel subway tunnels between the future Wilshire/La Brea Station and the existing Wilshire/Western Station.
Metro officials said it took Soyeon, which was originally lowered into the ground at Metro’s Wilshire/La Brea station site in the Miracle Mile area last fall, eight months — working five days a week, 20 hours a day — to reach the bulkhead wall at the face of the Wilshire/Western subway terminus. Anticipating future westward subway expansion, the transit agency built the retaining wall as part of construction of the station, which originally opened in 1996.
The second TBM named “Elsie,” which was launched six weeks after Soyeon, is also expected to break through to Wilshire/Western later this month, according to Metro. When done tunneling this project section, both TBMs will have mined nearly half a million cubic yards of earth.
“Our tunneling achievements to date prove that we can successfully mine through some of the most challenging conditions that any subway project anywhere in the world is likely to face,” Metro CEO Phillip A. Washington said.
After tunneling this leg, both TBMs will be used to tunnel west to future station sites at Wilshire/Fairfax and Wilshire/La Cienega. The machines are expected to reach the end of the four-mile subway section in Beverly Hills by mid-2020.
Following the tunneling operation, Metro said it will focus on completing construction of its first three subway stations over the next three years.
The $9.8 billion, nine-mile underground subway project will extend the Metro Purple Line from its current terminus in Koreatown to the Westwood/VA Hospital in west Los Angeles. The first section is scheduled to be completed in 2023, the second in 2025 and the third in 2027.
People can follow the TBMs’ progress on Twitter at http://www.twitter.com/purplelineext.
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