Dive Brief:

• Tunneling on the Los Angeles Metro Purple Line Extension project hit a new milestone as boring operations reached the second stop on the first phase of the line, the Wilshire/Fairfax subway station, Skanska announced in late April.
• The 9-mile, $9.3 billion underground subway project’s first phase of work will add three new stations and just shy of 4 miles of new rail, with a 2023​ completion date. Section 1 is being delivered by a joint venture of Skanska, Traylor and Shea for the Los Angeles Metropolitan Transportation Authority.
• The Purple Line extension will connect downtown Los Angeles to the western section of the city and help alleviate the area’s notorious traffic problems.

Dive Insight:

Using a 1,000-ton, 400-foot-long tunnel boring machine nicknamed “Elsie,” workers had tunneled 60 feet a day for 20 hours a day five days a week since October, before breaking through on April 4. A second TBM is tunneling toward the Fairfax entry and is expected to arrive at some point this week.

Following the boring machines finishing tunneling, large amounts of work remain, including laying the tracks, adding the third rail, pouring a concrete floor, installing fire protection and radio capabilities, according to the Metro.

The joint venture was first awarded the $1.6 billion design-build contract for the western portion of the tunneling in 2014. In January of 2017, the L.A. Metro awarded a joint venture of Tutor Perini and O&G Industries the $1.3 billion design build contract to finish the second section of the subway, with the completion date in 2025. 

Then, in February of 2019, Tutor Perini and partner O&G Industries won the $1.2 billion design-build contract for the third section of the project, comprising two stations over 2.6 miles of rail.

The TBM’s are designed to minimize ground settlement during boring and excavation. Pre-cast concrete lines the tunnel, bolted with gaskets to make sure it is water and air tight. 

Another high-profile tunneling operation has been ongoing In Las Vegas, where Elon Musk-owned The Boring Company finished the first of two, 1-mile long tunnels for the Las Vegas Convention Center’s expansion project in February. The Boring Company machines are designed to tunnel underground more rapidly than traditional machines. The Las Vegas tunnel is expected to be complete in January 2021, and The Boring Company may be making moves for a larger tunnel underneath the city as well.