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Flatiron + HOCHTIEF = Expert Builders and Tunnelers under One Roof

Flatiron's Tunneling Group focuses on large-scale tunnel projects across the U.S. and Canada. Flatiron works in close concert with tunneling experts from our parent company, HOCHTIEF, combining local resources, project management expertise, and experience on large-scale civil projects with HOCHTIEF's technical tunneling expertise to offer clients expert builders and tunnelers under one roof. As one of the largest international tunneling contractors in the world, Flatiron's parent company, HOCHTIEF, has completed more than 400 miles of tunnel for more than 400 different projects since 1945.

Tunneling Portfolio

Flatiron + HOCHTIEF Tunneling Services Portfolio 


  • Slurry and EPB shield tunneling
  • Hard rock TBM tunneling
  • NATM/SEM tunneling
  • Drill and blast tunneling
  • Conventional soft ground tunneling
  • Immersed tube tunneling
  • Cut & cover tunneling
  • Ground freezing, jet grouting and caissons
  • Project management
  • Tunnels/Shafts/Construction pits
  • Caverns & underground structures
  • Track bed/M&E works
  • Work in densely populated environments
  • Underpassing rail, road and other structures
  • Innovative solutions in all project phases
  • Preconstruction and value engineering
Lenihan Dam Outlet Modifications

Lenihan Dam Outlet Modifications - Los Gatos, CA

At the foot of the Santa Cruz Mountains, Flatiron replaced the deteriorating outlet structure for the 50-year-old Lenihan Dam - a 1,000-foot-long earthen barrier holding water stored at the Lexington Reservoir in Los Gatos, Calif. The project was a seismic upgrade for…