The future subway will operate mostly under Wilshire Blvd. There are segments, however, where the tunnel will pass below homes and businesses in the southwest neighborhood of the City and Beverly Hills High School. The tunnel will also travel beneath homes and businesses between Century City and Westwood.

The subway tunnels will generally be between 50 and 70 feet below the surface, reaching depths greater than 100 feet in some areas. Few, if any, impacts are expected at the surface from tunnel construction. Unlike the subway stations, which are excavated from the street surface, tunnels are dug completely below ground using the latest tunneling technology. All tunnels are engineered to withstand the weight of soil and structures, as well as potential seismic events.