Tunnel boring machine finishes its work on first of two twin tunnels for Regional Connector

Attentive Source readers know that the Regional Connector project is building twin 1.9-mile rail tunnels under downtown Los Angeles to connect the Blue, Expo and Gold Lines.

The good news from Tuesday: the tunneling of the first of those tunnels was completed when the tunnel boring machine (TBM) reached the intersection of 4th and Flower. The TBM launched from Little Tokyo in early February.

The remaining section of the tunnel between 4th and Flower and 7th and Flower will be dug by the cut-and-cover method — from the surface down — instead of by a TBM. The reason: tunneling in this section is difficult due to the many large buildings and foundations in the area.

As for the machine, it will be disassembled, trucked back to Little Tokyo, inspected and then rebuilt and relaunched to dig the second tunnel.

When completed, the Regional Connector will create two light rail lines: one that runs between Azusa and Long Beach and the other that runs between East Los Angeles and Santa Monica. The two lines will share five stations in downtown L.A. and will make travel to and through DTLA faster and more convenient with fewer transfers.

The Regional Connector is currently forecast to be completed in late 2021. It is funded by Measure R and federal and state grants.

3 replies

  1. Hi Steve,

    According to Figures 2-10 and 2-16 of the FEIS/R, the segment from the underground wye (just east of Alameda and 1st Streets) to the north of Temple Street will be “underground.” Will it be a ditch or a tunnel? Any comments on that at this time?

    I am curious!

    • Yes, the tracks will go under Temple Street via cut-and-cover method. That will be a good thing as trains sometimes have to stop at Temple to allow vehicular traffic to pass and that creates slower rides for light rail passengers.

      Steve Hymon
      Editor, The Source