The West Portal, located between Brokaw Road and I-880 (Newhall Yard) serves as the launching point for the Tunnel Boring Machine (TBM) to dig the five-mile tunnel. The West Portal is located along a construction site that crosses between the City of Santa Clara and City of San José. The West Portal refers to the overall construction site where many support facilities are located as well as the launch shaft where the TBM will begin tunneling. 

The West Portal serves as the assembly and eventual launching point for the TBM, and accordingly, the area will house many large support structures.