The replacement structure is approximately 2,600 feet long on an offset alignment about 300 feet downstream from the existing bridge. Two 12-foot traffic lanes with a 4-foot inside and 10-foot outside shoulders are provided in each direction. The total deck width is 81 feet including a median barrier. An 800-foot wide zone of disturbed rock associated with a fault zone exists in the river channel. The new structure provides a navigation clearance of 300 feet horizontally and 52 feet vertically.

An eight-span structure which blends prestressed concrete beam and steel girder spans was designed for the crossing. The main span unit consists of a five-span continuous steel girder arrangement with spans of 250, 300, 325, 350 and 250 feet. The main span unit is framed by a 134-foot simple span prestressed concrete beam span at one end and a two-span, 268-foot prestressed concrete beam unit at the other. The end spans of the steel girder unit are haunched to meet the depth of the prestressed concrete beam spans. The substructure units are founded on 9-foot diameter drilled shafts.

Modjeski and Masters, Inc. provided engineering services which included preliminary and final roadway design, hydraulic design, vessel collision studies, and geotechnical design for both the steel and concrete alternatives. Modjeski and Masters also provided preliminary and final design for the steel bridge alternative to replace the existing bridge. A concrete alternative design was prepared by another consultant.

This structure was designed according to AASHTO’s new probability-based Load and Resistance Factor Design bridge specifications. .