The machine broke through at the Wilshire/La Cienega subway station in Beverly Hills on 25 February; the second TBM is due to reach the station shortly. Tunnelling on the 6.3km Section 1 (three stations) is now two-thirds complete, while excavation of all three subway station boxes beneath Wilshire Boulevard has been completed. Metro expects TBM excavation to be completed by this summer.

Contractor Skanska Traylor Shea JV (STS) is constructing Section 1 under a design and build contract. It has used a pressurised, closed-face Herrenknecht TBM to minimise ground settlement during excavation, having started mining at the Wilshire/Fairfax station on May 29 2020. Breakthrough was achieved on February 25 after tunnelling around 18m/day through a difficult combination of soils and geologic conditions, including tar sands and methane gas. Along the way, the machine has installed a precast concrete lining comprising bolted and gasketed segments.

The Metro Purple Line Extension is a 14.4km underground subway project that will extend the Metro Purple Line from its terminus in Koreatown to Westwood/VA Hospital in West Los Angeles. Section 1 is expected to be completed in 2023, Section 2 in 2025 and Section 3 in 2027. When complete with its seven new stations, the line aims to provide easy access to the Westside, the region’s second-largest job centre. Travel time between downtown Los Angeles and Westwood is expected to take around 25 minutes.