The Hanging Lake Viaduct carries I-70 along the Colorado River through an extremely steep and narrow portion of environmentally sensitive Glenwood Canyon. Pressure from both the general public and public agencies dictated that the design of the highway through the canyon blend with the sensitive environment and not disturb the natural beauty of the canyon.

The project consists of two bridges totaling approximately 8,400 lineal feet with typical span lengths of 200’. The eastbound structure is 1310’ long and the westbound bridge follows the steep, rocky slopes for 7120’. Both structures emerge from twin tunnel portals at the west end of the project and cross the Colorado River with 300’ spans. The eastbound structure ends at grade while the westbound structure rises to 80' above the existing roadway and terminates in the Reverse Curve Tunnel at the east end of the project. The bridges were built using precast segmental concrete box girders, which met the project requirements for overhead erection, aesthetics, and schedule.

Hanging Lake Viaduct features the innovative use of temporary straddle bents that allowed construction over active traffic on U.S. 6. After traffic was switched to the new viaduct, piers were built beneath the new structure, then the load was transferred from the temporary bents to the new piers, while there was active traffic on the viaduct. The viaducts also feature the initial application of mid-span rotation restrained expansion joints. This allowed the construction of all cantilevers without having to accommodate intermediate expansion joints in the cantilever, simplifying construction.