The $2.1-billion Purple Line Extension Transit Project Section 1 in Los Angeles reached a major milestone recently, as two tunnel boring machines (TBMs) began carving out twin tunnels for the project.
One of Metro’s “priority projects,” the Purple Line Extension will provide a high-capacity, high-speed alternative for commuters to travel between downtown Los Angeles, the Miracle Mile, Beverly Hills and Westwood, where stations will be near UCLA and the VA Hospital.
From the current terminus at Wilshire/Western, the Purple Line Extension will extend westward for about nine miles and add seven new stations providing easy access to the Westside, our region’s second-largest job center. Travel time between downtown Los Angeles and Westwood is expected to be about 25 minutes.
The project is being built in three sections. The first section between Wilshire/Western and Wilshire/La Cienega is now under construction and is scheduled for completion in 2023.
Construction is being led by the STS (Skanska, Traylor Bros., Inc. (Traylor) and Shea) joint venture. Stantec is providing construction management support services to assist Los Angeles County Metropolitan Transportation Authority (Metro) in overseeing the design-build mainline and design-bid-build utility contracts.
The Section 1 tunneling is being dug by two TBMs affectionately dubbed Elsie and Soyeon that are 22 ft in diameter and about 450 ft-long. Made in Germany by Herrenknecht, they were designed to be project-specific, with a certain diameter and soil condition in mind. The machines cost $18 million each and were purchased for this project and assembled in the underground station box.
The TBMs bore on average about 50 ft a day. Paul Ryan, Stantec’s administrative project manager overseeing the construction support services contract, told me that to create two tunnels between Wilshire/Western and Wilshire/La Cienega the TBMs will work five days a week, 20 hours per day and will require about 24 months to complete their job.
The TBMs will dig tunnels side by side starting at Wilshire/La Brea in the Miracle Mile section of Los Angeles and continue east toward Wilshire/Western in Koreatown. Then they will be disassembled and transported back to Wilshire/La Brea where they will be reassembled to complete the westward leg of their journey. The machines will dig through Wilshire/ Fairfax and finish tunneling at Wilshire/La Cienega in Beverly Hills.
“The building of the Purple Line 1 Extension project faces challenges associated with building a mega-infrastructure project in a highly developed urban setting,” says Ryan. “Hundreds of utility lines must be relocated while maintaining services such as power, water, and communications, to the thousands of business people and residents along the alignment.”
He says the community along this 3.9 mile segment must be kept informed of ongoing plans and construction activities so that the area can continue to operate as a financial center of Los Angeles. “Impacts during construction must be minimized so that traffic and business can operate in a safe and productive manner,” says Ryan.
Section 2 of the Purple Line Extension Project will extend the subway to downtown Beverly Hills and Century City. Section 2 is currently in pre-construction and will begin construction later this year. Sections 1 and 2 are funded primarily by Measure R — the sales tax Los Angeles County voters approved in 2008 — and with a pair of federal grants.
Section 3 will then extend the project to two stations in Westwood. The passage of the Measure M sales tax ballot measure by county voters in 2016 will allow this section to be accelerated. Pre-construction activities on this section will begin in Spring 2018. Metro says it is currently working to secure the federal funds for Section 3.
