Major Construction Milestone Connects Downtown and West LA
The Los Angeles County Metropolitan Transportation Authority (Metro) has reached a significant milestone in its D Line Subway Extension Project, marking the completion of tunneling that will link downtown L.A. with West L.A.
This achievement comes after safely navigating one of the busiest and most geologically demanding urban corridors in both the Los Angeles region and the nation.
“This safe completion of tunneling through this part of Los Angeles is a milestone in Metro’s work to expand fast and reliable public transit across the region,” said Karen Bass, L.A. City Mayor and Metro Board Chair. “When completed, the D Line extension will make Metro transit available to 53,300 more weekday riders traveling between Downtown Los Angeles and the Westside. Thank you to all of the construction workers who have given their time and talent to successfully complete the tunneling.”
With tunneling now finished, Metro will continue collaborating with its two contractors in a joint venture with Skanska-Traylor-Shea and Tutor-Perini/O&G to finalize seven new underground stations spanning across three sections: from Wilshire/Western to Wilshire/La Cienega, Wilshire/La Cienega to Century City, and Century City to Westwood.
Employing the latest Tunnel Boring Machine (TBM) technology, contractors excavated approximately 40-60 feet per day to facilitate the tunneling process. The state-of-the-art TBMs, measuring 400 feet in length and 21 feet in diameter, utilized closed-face, pressurized TBM technology to minimize ground settlement during excavation. Additionally, the machines lined the tunnel with precast concrete segments bolted together to form secure rings, ensuring water- and gas-tightness to mitigate associated risks.
“The D Line Subway Extension is one of the most complex engineering feats that Metro has undertaken,” said Lindsey Horvath, Chair of the LA County Board of Supervisors and Metro Board Member. “Its complexity is matched by the immense value the project will bring to Los Angeles when it opens and carries 30,000 daily riders through one of our densest and most job-rich regions.”
Throughout the five-year tunneling process, Metro confronted and surmounted various technical challenges, such as gassy ground, tar sands, and abandoned oil wells. Near the La Brea Tarpits, the advanced TBMs navigated through tar sands and employed horizontal directional drillings to identify and remove potential obstacles, including unmapped and abandoned oil wells beneath Beverly Hills High School.
“Congratulations to Metro and its contractors for reaching a critical milestone for the D Line Subway Extension,” said L.A. County Supervisor and Metro Board Member Holly J. Mitchell. “We are one major step closer to a Los Angeles where everyone has access to all the cultural and economic resources the region has to offer.”
“Now that tunneling is complete, it won’t be long before Metro completes this mega-project and makes it possible for everyone to travel from downtown L.A. to West L.A. in under 30 minutes,” said Katy Yaroslavsky, L.A. City Council Member and Metro Board Member. “This subway extension will catalyze ridership on the entire Metro System in the years ahead, bringing many thousands of new riders throughout Metro’s transit system.”
“The end of tunneling work on this project is a triumph of engineering, planning and execution. Our construction team undertook a painstaking process that helped us keep everyone in these communities safe and deliver a better project for the people of L.A. County,” said Stephanie Wiggins, Metro CEO. “We have proven yet again our capability to safely tunnel underneath a range of different structures as well as sensitive and historic sites.”
The forecasted openings are 2025 for Section 1, 2026 for Section 2, and 2027 for Section 3 of the project.
Metro funded the project locally through the 2008 Measure R and 2016 Measure M voter-approved transportation sales tax measures, with federal funding matching approximately half of the project’s overall cost.
