When the Regional Connector project is completed, three Metro light rail lines — the A (Blue), E (Expo) and L (Gold) — will finally be joined together via a pair of 1.9-mile twin tunnels under downtown Los Angeles. Connecting three rail lines is a massive, complex and ambitious feat that is unique among rail projects in the United States, past or present.

Making things even trickier: these three busy rail lines will continue to offer service during construction of the $1.8-billion Connector project, which is presently 63 percent complete.

We’ll get to the construction challenges in a moment, but first let’s look at the substantial benefits for everyday riders and those who don’t know much about the project:

•Eastside L Line (Gold) riders will no longer have to ride all the way to Union Station first and then transfer to the subway to reach the heart of downtown L.A. Instead, trains from the Eastside will enter the new rail tunnel at 1st and Alameda and continue to 7th/Metro Station with stops along the way at 1st and Central (to access Little Tokyo and the Arts District), 2nd and Broadway (the Historic Broadway corridor and Civic Center) and 2nd and Hope (Grand Avenue, i.e. the Music Center, Disney Concert Hall, the Broad, etc).

•Similarly, L Line riders coming from Azusa will no longer have to exit their trains at Union Station and transfer to the subway — a time muncher of a transfer. Instead, L Line trains will continue from Union Station through downtown to 7th/Metro and then beyond.

•A Line and E Line riders will not have to exit trains at 7th/Metro, the current terminus of both lines. Trains at 7th/Metro will continue north through downtown and then run either to East Los Angeles or Azusa.

In essence, the Connector fundamentally changes the way Metro operates its rail system. With more direct service and by reducing or eliminating transfers, commuting times for riders will be reduced by up to 20 minutes.

The project also creates new operational possibilities for Metro’s light rail system. One example: via the new tunnel, we could run trains from Santa Monica to East L.A. Or between Azusa and Long Beach, a distance of more than 40 miles. An operational plan for the project will be considered by Metro’s Board of Directors later this year.

“We could have easily maintained the status quo with these three rail lines and never tried to connect them because doing so would be too difficult,” said Metro CEO Phillip A. Washington. “Instead, Metro rose to the challenge. We’ve successfully tackled every obstacle this project has thrown at us — and we’ll keep doing so until the project is complete. The project will confer enormous benefits on riders with faster trips to and through downtown L.A. with far fewer transfers and one seat rides across huge swaths of Los Angeles County.”

The original plans for the Gold Line to Pasadena in the 1990s involved extending the line through DTLA to 7th/Metro to connect with the A Line (Blue). Funding challenges and politics prevented that from happening. The idea was revived after voters in 2008 approved Metro’s Measure R sales tax which provided local funding that, in turn, attracted enough federal dollars (a $670-million grant and $160-million loan) to build the project.

In the early planning stages, the project was envisioned as being a street-level project. That idea was scuttled after many stakeholders argued trains should be underground to avoid running amid vehicle traffic. Another benefit: the tunnels helped preserve one of the three remaining Japan towns in the nation.

Tunneling, of course, greatly raises the cost of a project. In the case of the Connector, tunnel depths range from 25 feet to nearly 120 feet below street level. At 2nd and Hill, the new tunnels cross under the Metro B (Red) and D (Purple) Line tunnels with just seven feet of clearance.

As for construction, one mile of the tunnels was excavated using a 400-foot-long tunnel boring machine while digging from the street (cut-and-cover) was used to the build the tunnel under Flower Street between 3rd and 7th streets during weekends to minimize impacts to the Financial District. To connect the new tunnels to the existing 7th/Metro Station, walls were removed using wire concrete saws to avoid impacts to A and E Line operations.

“The complexity of building a transit project in a high-density area is always a great challenge, and building this type of complex transit project in the heart of downtown Los Angeles magnifies that ten-fold,” said Metro’s Chief Program Management Officer Richard Clarke, whose department is overseeing Metro’s contractor, Regional Connector Constructors.

Another huge challenge was building new rail tunnels through the maze of utilities and building foundations in DTLA while ensuring utility service continues for businesses and the growing number of residents in DTLA. The utilities include electrical, telephone, fiber optic, sewer lines, storm drains and natural gas lines, some of which were more than 100 years old and badly in need of repair. For example, Metro had to replace deteriorated electrical lines in the Civic Center at a cost of more than $27 million.

To clear the way for the station at 2nd and Broadway, Regional Connector crews in 2017 had to excavate around a decades-old concrete storm drain. Metro replaced the pipe with stronger materials and then suspended the new pipe from the station’s temporary ceiling. This creative engineering allowed the storm drain to remain in service during construction.

Excavating stations amid downtown has also been a big task. The bottom of the new station at 2nd and Hope will be 110 feet below street level, making it the deepest in the Metro system. Metro also had to create a 287-foot-long cavern under 2nd Street to accommodate switches between the tracks.

“Excavating the cavern is one of the construction milestones we’re most proud of,” said Metro’s Executive Officer for the Regional Connector, Gary Baker. “This is a massive undertaking, the likes of which haven’t previously been seen in L.A. County.”

The work in Little Tokyo also presented unique hurdles. To build the tunnel portal in the middle of 1st Street for the Eastside Gold Line, tracks were shifted to the north side of the streets in 2016. That tunnel portal is now almost complete.

Now a second portal must be built for trains to/from Azusa. There isn’t the space required to move the tracks, so bus shuttles will replace rail service between Union Station and Pico/Aliso Station this fall. That allows Metro to dig the new tunnel portal, demolish the existing Little Tokyo/Arts District Station and then build a new ramp to the bridge that carries trains over the 101 freeway. The work is expected to begin this fall and take 22 months to finish. When completed, full rail service from East L.A. will resume with trains running directly into downtown L.A.

After the tunnel structures and tracks are done, there is the tough work ahead of integrating communication and signal systems of three rail lines built at different times and then testing the systems and trains. There are undeniably big hurdles to clear, but with a big payoff to Metro customers when everything is finally done.

“The Regional Connector provides the missing link between three separate rail lines — a project unique in our region and elsewhere,” said Gary Baker, Metro’s Executive Officer for the Regional Connector. “There is not another transit project here in the United States that is currently building this type of underground system that will serve so many people and help them save so much time.”

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