Bridge Design and Investigation

Bridge Scour Investigation

Straits of Mackinac, MI

Owner: Mackinac Bridge Authority

The Mackinac Bridge, constructed during 1954-57, is the ninth largest suspension bridge in the world. It has a total length of five miles and a main span of 3800 feet.

Ocean Surveys conducted an ultra high resolution multibeam hydrographic survey of the lakebed adjacent to thirty (30) bridge piers to generate an extremely detailed digital terrain model (DTM) for the purpose of identifying and detailing scour activity. Data deliverables included contoured plan, isometric and profile presentations.

Figure 1: One of the thirty Mackinac Bridge piers investigated for scour assessment using OSI’s 455kHz multibeam sonar.

Figure 2: Plan view depth contour presentation of area adjacent to the pier.

Figure 3: Isometric presentation of bottom morphology adjacent to the pier.