L.A. Regional Connector is Halfway There

July 5, 2018
The Los Angeles Regional Connector project recently celebrated a key milestone when the new light rail transit line reached the construction halfway point.

The milestone was reached following the completion of a second 1.1-mile twin underground tunnel, which is part of the Los Angeles County Metropolitan Transportation Authority’s $1.81 billion project, a key part of a 1.9-mile rail line that will link three existing light rail lines and the city’s subway between the Little Tokyo/Arts District and 7th Street/Metro Center stations in downtown Los Angeles.

When completed, the rail line is expected to serve 88,000 riders daily — including 17,000 new riders — and save commuters up to 20 minutes by reducing the need to transfer when traveling to and through downtown Los Angeles. The Regional Connector is targeted for completion in late 2021.

The second tunnel was completed in January with the use of a state-of-the-art tunnel boring machine (TBM) manufactured in Germany by Herrenknecht AG. Named “Angeli,” the TBM weighed about 1,000 tons, was 400 feet long and nearly 22 feet in diameter. It advanced about 50 to 70 feet per day on average and mined 10,900 feet between the two tunnels, excavating over four million cubic feet, or 240,000 tons, of earth.

With both tunnels now fully excavated “Angeli” was dismantled and removed from the site.

Decade of Service

WSP, in a joint venture with AECOM as the Connector Partnership, is providing transportation planning, rail design and rail planning for the Regional Connector. Since joining the project in 2008, the firm’s responsibilities have included tunnel and geotechnical engineering, tunnel ventilation, rail systems, travel forecasting, operational analysis, and mechanical, plumbing and electrical engineering.

WSP is working on behalf of Metro with Regional Connector Constructors, the joint venture of Skanska and Traylor Brothers, Inc. that is contracted by Metro to design and build the project.

Milestone Celebration

On May 19, Los Angeles hosted “Halfway There!” – a community celebration attended by local and national officials as well as representatives from the firms responsible for the design and construction of the new light rail line. The event was held at the plaza of the Japanese American National Museum in Little Tokyo, across the street from the excavation site where the tunneling had started.

“The event was quite upbeat and uplifting, and everyone seemed to enjoy being there,” said Bill Hansmire, project manager for WSP USA. “The event celebrated the myriad of cultures that reflect the mosaic of Los Angeles. Japanese, Brazilian, African and American cultures were among those evident in the entertainment featured throughout the day.”

Los Angeles Mayor Eric Garcetti served as master of ceremonies. Speakers included Jose Huizar, Los Angeles City Council; Phil Washington, Los Angeles Metro CEO; and was attended by Norman Mineta, former U.S. Secretary of Transportation.

“Transforming the L.A. region through an aggressive transportation initiative has taken a giant step forward today as we reach a critical halfway point in this important project,” Washington said. “When completed, this project will be a real game changer for the entire region providing greater connectivity.”

Stakeholders located along the new Regional Connector line include the Walt Disney Concert Hall, the Colburn School, the Broad Art Museum, and other cultural institutions in the region.

“Transportation improvements aren’t just about building infrastructure — they’re about building new connections to the people and places that we love,” Garcetti said. “The Regional Connector will bring those connections to riders across the region, and today’s milestone means we’re one step closer to a one-seat ride from the Eastside to the beach.”

The Regional Connector Transit Project is creating “a vision for a more multimodal downtown Los Angeles (DTLA),” added Huizar. “The Regional Connector fits in with our DTLA Forward. Together, we must remain united in the goal of creating a great transportation network serving the entire region, with DTLA as our public-transportation center point.”

During the celebration, Hansmire led public tours near the excavation site where he explained the progress of the project and answered questions.

Firsts for L.A.

The Regional Connector tunnel includes some “firsts” for Los Angeles. It will be the first cavern excavated in weak rock in Los Angeles for a rail crossover that presently under construction using the sequential excavation method (SEM) of tunneling.

When completed, it will also be the first time that Los Angeles will use high-speed elevators instead of escalators for its Metro system. The new station planned for Second Street and Hope Street will feature six high-speed elevators with hoisting equipment located below the elevators—rather than above—to avoid the visual impact at the station entrance pavilion.

One of the project’s innovations involved the location of a fan plant at the junction of the two lines coming into Little Tokyo to provide ventilation for the underground transit lines. WSP’s design analysis confirmed that this scheme would work at this location, which resulted in a significant cost savings for the client.

“When it was determined an additional tunnel ventilation fan plant was needed at that junction, it created an opportunity to use the TBM launch pit beneficially,” Hansmire said. “So rather than being backfilled, it became the perfect location for the fan plant, thus avoiding additional excavation.”

One of the project’s big challenges is the relocation of utilities.

“It has been our biggest issue requiring some very careful coordination as we balance the competing demands of utility work that requires closing lanes of traffic, while accommodating roadway traffic during those construction times,” Hansmire said.

Fortunately, with the relocation or temporary support of utilities under the city streets now substantially complete and no new streets scheduled for major traffic closures for this type of work, those difficulties appear to be in the past.

A New Focus

With tunneling and final design largely complete, WSP’s services are transitioning to focus on rail transit systems. WSP staff will be involved in the process leading to rail activation, and will provide technical assistance after the start of operations.

Contractor procurement of systems and other equipment is in progress, which involves review of all product submittals. WSP is also witnessing and evaluating some factory acceptance tests for equipment manufactured in Los Angeles area and some from Canada.

“Flower Street from Fourth Street to Sixth Street is nearly decked over,” Hansmire said. “Only the intersection of Sixth and Flower Streets remains to be decked over to permit the cut-and-cover construction to be completed below the street while traffic is maintained above.”

The next stage of the project includes construction of three new passenger stations:
• Little Tokyo/Arts District Station at 1st Street and Central Avenue,
• Historic Broadway Station at 2nd Street and Broadway, and
• Grand Avenue Arts/Bunker Hill Station at 2nd Street and Hope Street.

All station finishes will include installation of escalators, elevators, lights and signs.

“The 1st and Central and Second and Hope stations are fully excavated and concreting has started,” Hansmire said. “The 2nd and Broadway station is within 20 feet of full-depth excavation, which will reach a depth of about 90 feet. At the east end of the 2nd and Broadway Station, the SEM cavern is the last technically difficult underground construction remaining, and excavation expected to take about one year.”

In addition, construction teams will handle the excavation and concreting of the crossover cavern, installation of all rail and transit systems, and the final restoration of the streets impacted by construction.

“Three cross-passages in the TBM-excavated tunnels have been excavated and in are the process of having the HCR [hydrocarbon resistant membrane] installed, rebar placed, and final concrete placed. Construction of tunnel walkways is also in progress,” Hansmire said. “Final design of the project is being closely coordinated with several departments of the City of Los Angeles.”

'Everything Is Included'

Hansmire said the multidisciplinary scope of the Regional Connector project has been a professionally rewarding opportunity to use his many years of project management and technical engineering experience.

“The Regional Connector project encompasses all technical disciplines for underground rail transit … everything is included,” he said. “It’s not just geotechnical, structural and tunnel engineering, but also architecture, mechanical and electrical engineering, and transit systems, including traction power, communications and train control. We have the opportunity to contribute in a larger way to making the city a better place to work and live for coming generations.”