Tunnel mining in Downtown Los Angeles
The Regional Connector Transit Project will construct two parallel tunnels to create seamless transit connections of the Expo, Gold, and Blue Lines. The new 1.9 mile railway will be constructed using a combination of tunnel boring machine and an “open-cut” method. Angeli will be responsible for 1.1 miles of tunneling, as she travels westerly from Little Tokyo to the Financial District. Each tunnel will take approximately six months to complete.
Along the way, Angeli will encounter different soil conditions. Progress is measured in total feet traveled and the number of rings she builds. Follow Angeli on Twitter for weekly updates on her progress and more.
Angeli is tunneling through the sand and gravel deposited by the ancient Los Angeles river for the first portion of her journey. Because the machine is shallow, grouting has been done in order to hold the ground in place.
Zone 1 – From Central Av to San Pedro St
Angeli will be tunneling through the sand and gravel deposited by the ancient Los Angeles river for the first portion of her journey. Because the machine is shallow, grouting has been done in order to hold the ground in place.
Zone 2 – From San Pedro St to Broadway
Angeli is tunneling slightly downhill through the Fernando bedrock formation, which is a soft rock that is very much like hard clay. She will be tunneling through the future Station under 2nd Street between Spring St and Broadway St, which will be excavated later in the project.
Zone 3 – From Broadway to Hope St
Angeli is tunneling uphill through Bunker Hill under the Red Line and then under the 2nd Street tunnels. Tunneling will continue to be in the Fernando bedrock formation, which is a soft rock that is very much like hard clay.
Current Location: Zone 4 – From Hope St to 4th St
Angeli will take a left turn at the future Station near Hope and 3rd St. and will tunnel under Flower St to the end of her journey at 4th St. The ground in this section is mostly the Fernando bedrock formation, there will be sand and gravel deposits however near the top of the tunnel.
|Zone||Total Feet to Tunnel||Rings to Build|
|Central Av to San Pedro St||790||158|
|San Pedro St to Broadway||1985||397|
|Broadway to Hope||1670||334|
|Hope to 4th St||1050||210|
|Total||5820 feet per tunnel||1099 rings per tunnel|