The Gordie Howe International Bridge is a planned border crossing spanning the Detroit River, connecting Detroit, MI to Windsor, Ontario, Canada. This Complex cable-stayed design calls for a main structural support tower on each side of the Detroit River to support what will be one of the largest bridge structures in North America. These support towers (expected to be over 700 ft above grade elevation) are founded on drilled shaft supports that extend down through various geological subsurface conditions and into the limestone bedrock below. In addition to the main support tower, the cable stayed bridge is anchored back with a series of back span/anchor piers. Similar to the main support tower, these back span/anchor piers are founded on drilled shaft supports, that extend down through various geological subsurface conditions and into the limestone bedrock below.
In addition to the general complexity of large diameter shaft drilling, we had to be content with a nearly 20 ft. artesian pressure head, hard rock drilling (15,000+ psi limestone), the presence of hydrogen sulfide, and typical Detroit winter weather. To combat artesian water pressure, we installed all shafts while carrying an additional 25 ft fluid head above grade during the entire drilling process until initial hydration of the concrete. With the use of a permanent/sacrificial starter casing section, in conjunction with our temporary segmental casing, we were able to maintain a positive slurry head without the waste of additional permanent casing to extend this fluid head above the grade after concrete placement.
