Tacoma Narrows Briefing

• Design-Build job
• Project involves seismic retrofit of the existing Tacoma Narrows Bridge and construction of a second bridge, with truss deck
• Wind tunnel testing (section & full model) at RWDI in Canada demonstrated that presence of two bridges actually improved the aerodynamics on site
• Once new bridge is completed, existing bridge will be converted to a 3 lane, one-way bridge
• Caissons are now being dropped
• The caissons each have 15 dredge wells and will be cast until they sink through the 150 feet of water and then 60 more feet into the bottom of the Narrows
• 32 anchors hold each caisson in place as they are cast downward, fighting strong currents
• New bridge tower will be 510 feet
• Historical Constraint: Construction must not damage pieces of original bridge still on bottom