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US 90 over Biloxi Bay
Between Harrison and Jackson Counties, Mississippi

Prior to its destruction by Hurricane Katrina, US 90 carried traffic 1.6 miles over Biloxi Bay, connecting Biloxi with Ocean Springs, MS. It is a relatively modern design, using pre-stressed concrete girders with a cast in place deck. The fact that the spans were simply supported (i.e., not continuous) was probably the most significant contributor to its collapse.

The bridge was made up of numerous simply supported spans, each measuring 42 feet in length. Newspapers reported water elevations over 20 ft deep caused by storm surge, which was substantiated by debris entangled in nearby trees.

Many spans close to the water have been lost. The spans near the navigation channel were elevated to allow for passage of boat traffic. These survived (see figure 1), while the spans lower and closer to the water were broken up by wave and wind action and/or severely displaced.

The second span from the eastern most abutment was displaced 16 feet to the north by the rising water and strong winds. Other spans were moved as much as 47 feet (see figure 2), causing them to fall entirely off the end of the pier cap. In other spans, repeated lifting and dropping of the concrete bridge battered and broke many of the prestressed beams and the reinforced concrete deck (see figure 3). Away from the shore, many spans collapsed into the water.

Figure 4 shows how the steel reinforced concrete deck has been battered and now lays disheveled. A personal interview revealed that local police had video taped the turbulent waters beating against the bridge about 4:00 am August 29, 2005. Upon their return after the storm, the bridge was in the condition shown in the photo.

Figure 5 shows that the reinforced concrete deck has been peeled away from the prestressed concrete girder and has broken transversely, exposing its steel reinforcement.

Photo of Concrane Africatown Bridge

Figure 1. This view is looking southwest toward Biloxi from Ocean Springs. The higher spans over and near the navigation channel received much less damage.

Photo: J. O'Connor (for MCEER)

Figure 2. The spans nearest the eastern shore shifted as much as 47 feet to the north, causing them to fall off the pier cap.

Photo: J. O'Connor (for MCEER)

Photo of Concrane Africatown Bridge

Figure 3. The span twisted before dropping, severely breaking up the concrete deck.

Photo: J. O'Connor (for MCEER)

photo of damaged bridge

Figure 4. View of the west end of the Biloxi Bay bridge looking east.

Photo: J. O'Connor (for MCEER)

photo of damaged bridge

Figure 5. View of the eastern span facing west.

Photo: J. O'Connor (for MCEER)

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