This is an archival story that predates current editorial management.
This archival content was written, edited, and published prior to LAist's acquisition by its current owner, Southern California Public Radio ("SCPR"). Content, such as language choice and subject matter, in archival articles therefore may not align with SCPR's current editorial standards. To learn more about those standards and why we make this distinction, please click here.
Here's What A Giant Tunnel-Boring Machine Looks Like In Action 60 Feet Under The Streets Of L.A.
Back in 2012, Metro approved a Regional Connector project to connect the Expo Line, Blue Line, and Gold Line, in order to end the madness of changing to the Red Line to traverse the 2 miles separating one side of downtown to the other. Construction on the new tunnels finally began in March after years of gathering funds and contests to name the tunnel-boring machine. Now, 10 weeks into construction, the L.A. Times has taken an in-depth look at the extensive mining operation occurring under our feet.
The tunneling begins at 5 a.m. each day, with mechanical engineers, operators, and miners executing a non-stop cycle of digging the tunnel and building the rings that keep the tunnel safe and secure. The machine averages three inches every minute, so a 10-hour shift can cover as much as 70 feet (provided the soil co-operates and no machinery breaks down). The group of miners—often exclusively men—functions as a family of adrenaline-junkies. Richard McLane, chief mechanical engineer for the Regional Connector Project, explains how tunneling is so addictive because "It’s like watching civilization in action. This is not a leaf spring for a Chevy Camaro that in 10 years will be in a junkyard. The work we do will last generations.”
The tunneling process encountered extreme difficulty at the beginning because the soil under Little Tokyo contains the unyielding remains of the Los Angeles River floodplain. Once the miners reached the silt and clay soil known as the Fernando Formation, they could breathe easy (and also celebrate with a rendition of ABBA's Fernando, according to the Times). The consistency of the soil isn't the only factor the miners interact with on a daily basis. Tunneling near the Red Line allows for a tiny, 4-inch margin of error. The tunnel has to maintain a level of upward pressure in order to avoid moving the ground (apparently, during construction of the Red Line, Hollywood Boulevard sunk 10 inches). This process includes consistently measuring the quantity of excavated dirt. If it exceeds calculations, the tunnel is at a much higher risk of causing land to sink or cave in.
The product of this tunneling—the Regional Connector—will open in 2021. Three new Metro stops will open at 2nd/Hope, 2nd/Broadway, and 1st/Central, and the Expo, Blue, and Gold Lines will extend their paths across downtown. Public transportation downtown will become a little less maddening, and contemporary Angelenos' dream of a connected, transportation-friendly future will continue transforming into a reality.