Video: Regional Connector tunneling machine reaches another milestone

The tunnel boring machine (TBM) for the Regional Connector resurfaced Friday at the future Grand Avenue Arts/Bunker Hill Station. The TBM began digging the second tunnel on the project in late September and traveled approximately 4,400 feet from Little Tokyo to reach the deepest station on the alignment.

Crews used what they learned from building the first tunnel to dramatically increase their rate of production on this tunnel. Typically, TBMs will travel 60 feet to 100 feet per day when working in similar soil conditions. The TBM, however, traveled a remarkable 190 feet in a single day — the TBM’s personal best — and averaged more than 400 feet per week. Crews erected 739 precast concrete rings to build the tunnel so far.

The TBM will now be walked through the station and re-launched at the west end by the end of the month. To complete the second tunnel, the TBM will need to dig through another 1,370 feet of soil to reach the extraction point at the intersection of 4th and Flower streets in early January.

The $1.75-billion Regional Connector Transit Project is a 1.9-mile underground light-rail extension that will connect the Blue, Expo, and Gold Lines in downtown Los Angeles and will include three new stations. The project will reduce the need to transfer on Metro’s light rail system and make trips to and through DTLA faster and more convenient. The project is scheduled to be completed in late 2021.

2 replies

  1. Did they say how much time they saved with the increased tunneling speed? I assume it won’t be enough to make up for the setback from replacing that old water pipe, but completing it even a few days earlier than expected is good news.

    • Hi Pat;

      I think the savings was basically a few days — probably not enough to make up for the utility issues. But it’s good to hear tunneling is quicker.

      Steve Hymon
      Editor, The Source