D Line Subway Extension Project subway expansion project marks new milestone, Los Angeles

Tunneling the D Line Subway Extension Project in Los Angeles, is complete. The LA Metro celebrated the milestone last week at the future Wilshire/Fairfax subway station on Los Angeles’ Miracle Mile. The 9-mile cost approximately $9.5 billion expansion. It runs from Koreatown to the Westwood/VA station. The project has been in the works since 2014 and was built in three stages.

Technology used for the tunnelling process

Contractors, who included Tutor Perini Corporation and O&G Industries, used the newest Tunnel Boring Machine (TBM) equipment to drill 40 to 60 feet per day to complete the project’s tunnelling. The 400-foot-long, 21-foot-diameter earth boring machines used closed-face, pressurised TBM technology. This reduced ground settling during excavation. The machines also lined the tunnel with precast concrete parts that were connected together to form strong rings. This crucial part prevented water and gas leaks. The same TBM technique was successfully used in L.A. Metro’s 2009 Eastside Extension Project. The machines passed through tar sands and abandoned oil wells beneath Beverly Hills High School.

The D Line Subway Extension Project Subway Sections

Section 1 includes the Wilshire/La Brea Station, Wilshire/Fairfax Station and Wilshire/La Cienega Station. It is slated to open first, in 2025. The second section includes the Wilshire/Rodeo Station and Century City/Constellation Station. It is scheduled to open in 2026. The third section includes the Westwood/UCLA and Westwood/VA Hospital stations. It is projected to be finished in 2027.

Now that the tunnelling is complete, construction personnel will focus on erecting the new stations, installing electrical components and finishing street restoration, according to a Metro spokeswoman.

The Los Angeles D Line Subway Extension Project Hurdles

Construction was repeatedly brought to a halt in 2022 owing to safety concerns. A 40-year-old construction worker was killed in March when he was hit by a service van transporting components and personnel around the site. Work was halted again in October 2022 when many additional workers were hurt. Pushback against tunnelling under Beverly Hills, particularly Beverly Hills High School, threatened to halt the project before it ever begun. In a Superior Court action, the Beverly Hills Unified School District tried to stop the work completely. In addition, the district filed a federal lawsuit to reroute the project.

“The D Line Subway Extension is one of the most complex engineering feats that Metro has undertaken,” claimed Lindsey Horvath, chairperson of the Los Angeles County Board of Supervisors and Metro board member. According to Metro, the machines surround the tunnel with precast concrete sections joined together to form secure rings that are both water and gas tight. The major objective will be to build seven more subsurface stations. “When completed, the extension will make Metro transit available to 53,300 more weekday riders travelling between Downtown Los Angeles and the Westside,” stated Karen Bass, Mayor of Los Angeles and Metro board chair.