The Metro BLOC Tunnel connects riders in Metro 7th Street Station directly to the shops and restaurants of the BLOC complex in Downtown Los Angeles.
The support system had to allow the connection to be excavated while the active roadway and public stairway above remained in service.
Cefali designed a beam-and-column support system that could be installed as excavation progressed from the BLOC toward the station. Before the station wall was removed, grout tubing was used to improve the ground and reduce the risk of caving.
The work involved confined spaces, access restrictions, fumes that prevented welding, low overhead, and multiple bolted splices in beams and columns. The system also had to stay clear of the permanent concrete passage for the final condition. Malcolm Drilling was the contractor that opened the passage.
