Indian River Inlet Bridge Replacement
Location
Sussex County, DE
Client
T Y Lin International
Services Provided
Deep Foundations
Temporary Anchored Sheet Pile Walls
Scour
Project Overview
The excessive scour that occurs in the Indian River Inlet has resulted in nearly 100-ft deep holes near the channel piers of the existing bridge, and problems with stability of the existing sheet pile walls. The Delaware Department of Transportation has begun the design of a new Signature Bridge for this site, which will have a clear span sufficient for the existing channel and possible future widening.
Schnabel performed review services for this design, as a member of the Quality Assurance Review Team led by T.Y. Lin International. The bridge will have two 240-ft high towers/pylons on each side with single plane cable stays. The new bridge will also be 2,500-ft long, including a 900-ft clear span over the inlet, with 1,700 ft of bridge decking over the land. All supports will be out of the water, eliminating the conditions that now exist with the existing bridge. The new bridge will have a minimum 100-year design life. The foundations will be supported on 36 inch square piles.
Due to this great length, the foundation loads at the main piers will be significant. Given the subsurface conditions along the ocean, which consist of interbedded layers of dense and loose sands, normally consolidated clays, and some minor organic deposits, the foundations will extend to depths exceeding 100 ft. The design team developed the main foundation recommendations and designs, Schnabel's engineers actively participated in the discussion of alternative comparisons, expected performance criteria, and constructability. The reduced embankment limits will result in the elimination of massive embankments and will provide an open view.