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US 90 to I-10 Ramp Bridge over Mobile Bay
Baldwin County, Alabama just east of Mobile

Location: N 30.67812, W 87.98909

The eastbound US 90 to eastbound I-10 interchange over Mobile Bay (Bridge ID# 011926) suffered structural damage even though it was located about 80 miles east from the center of the storm. The wind speeds in this region were estimated to be less than 80 MPH (NOAA Hurricane Research Division of AOML), though the damage was likely caused by the storm surge. The closure of this bridge did not appear to have a significant impact on traffic since the US 90 and I-10 run parallel to each other and alternate routes are available within a few miles

Figure 1 shows a picture of the bridge from the west. The bridge consists of simply supported single spans attached to the piers with clip angles. Three of these spans were shifted about 6 ft. to the north, knocking the girders furthest to the north from their supports. Concrete spalled at the corners of the pier caps as the clip anchors pushed north as shown in Figure 2. It is interesting to note that the span to the west of the shifted section was also constructed of concrete girders and remained in place even though it was at a lower elevation.

photo showing the bridge's displacment

Figure 1: Three simple spans shifted north about 6 ft on the US 90 to I-10 ramp bridge over Mobile Bay

Photo: J. O'Connor (MCEER)

close up of displacement

Figure 2 : The corners of the pier caps spalled as anchors attached to the girders pushed through the concrete cover.

Photo: J. O'Connor (MCEER)

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