TBM Hits Construction Milestone on LA Subway Extension

purple — The 22-ft-diameter Elsie broke through into second of three stations April 6. *Photo courtesy of Metro.*

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.

The Los Angeles Metropolitan Transportation Authority (Metro) announced the breakthrough on its official blog.

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.

Looking for quick answers on construction and engineering topics?
Try Ask ENR, our new smart AI search tool. Ask ENR →

Aileen Cho, ENR's deputy editor for infrastructure, is a born-again Angeleno and recovering New Yorker. She studied English and theater at Occidental College, where a reporter teaching the one existing journalism course encouraged her to apply for the LA Times Minority Editing Training Program. Her journalism training led to her first stories about transportation, working as a cub reporter with the Greenwich Time. She has been honored, solo or with ENR colleagues, with several journalism awards. For ENR, she has traveled the world, clambering over bridges, touring airports, and descending into tunnels. She is a regular at transportation conferences, where she finds that airport and mass transit engineers really know how to have fun (bridge engineers aren't far behind). She is always eager to hop on another flight because there are so many interesting projects and people, and she gets tired of throwing her cats off her computer in her home office in Eagle Rock, California. She is a very conflicted Mets/Dodgers fan.

Post a comment to this article

Live: July 16, 2026 at 2:00 pm EDT We'll address the current state of the construction market as we reach the halfway point of 2026. ENR invites three top forecasters asking them to share their views on the market prospects for the industry at midyear, both nationally & regionally, in the midst of these unique challenges.