Angeli, the tunnel boring machine mining the underground tunnels for the Los Angeles County Metropolitan Transportation Authority’s Regional Connector Transit Project, achieved a key construction milestone this month by completing the second tunnel and will now officially retire from the light rail project.

(photo courtesy of Metro)

“Angeli has been hard at work over the last year digging tunnels that will bring us an interconnected transit network, and today’s milestone is an example of the progress we’re making,” Los Angeles Mayor and Metro board Chair Mayor Eric Garcetti said.

Angeli was lowered into the ground near the Little Tokyo/Arts District Station at First and Central in late 2016 and began digging the tunnels in early 2017. The first tunnel was completed in July.

Angeli was then taken apart and transported back to the First and Central Station site in Little Tokyo where the TBM was reassembled to begin mining the second tunnel. That work was finished in January.

The tunnel boring machine was named Angeli, which translates into “angel,” as in the City of Angels. A contest was held among students to name the TBM and the winning name was submitted by Windsor McInerny, a ninth grader attending Woodrow Wilson Classical High School in Long Beach.

Naming of the tunnel boring machine pays tribute to a mining tradition that dates back to the 14th century. Saint Barbara, the patron saint for military engineers and miners, has long been revered by underground workers as a symbol of protection and good luck. This homage evolved into the tradition of giving tunneling machines a name before digging begins.

The $1.75-billion Regional Connector Transit Project is a 1.9-mile underground light-rail tunnel that will connect the Blue, Expo and Gold Lines in downtown Los Angeles and will include three new stations at First Street/Central Avenue, Second Street/Broadway and Second Place/Hope Street. 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 L.A. Construction is expected to be completed in 2021.

The tunnel boring machine was manufactured in Germany by Herrenknecht AG. It weighs approximately 1,000 tons, is 400 feet long and is 21.6 feet in diameter. It advanced about 70 feet per day on average and mined 10,900 feet between the two tunnels and excavated over four million cubic feet or 240,000 tons of earth.