With several subway projects in the bidding and building stages, and high-speed rail potential on the horizon, Los Angeles is setting the stage for plenty of underground action. This June will also see the tunnelling industry surface for the North American Tunneling (NAT) conference, which is organized by the Underground Construction Association (UCA), a division of the Society for Mining, Metallurgy, and Exploration (SME), and alternates each year with the Rapid Excavation Technology Conference (RETC). Tunnels has its definitive guide of who’s on show and what out-of-towners need to know in Los Angeles