US 90 Bridge over St. Louis Bay

In August 2005, the Bay Saint Louis Bridge was completely destroyed by Hurricane Katrina, severing a vital link between the towns of Pass Christian and Bay Saint Louis. As a major design sub-consultant on the design-build team of Granite-Archer/Western, RS&H provided design and post-design services for the eastern portion of the new Bay Saint Louis Bridge. A four-lane, high-level pre-stressed concrete girder bridge set well above the storm surge levels was designed to replace the two-lane, low-level trestle bridge destroyed by this extraordinarily destructive hurricane.

The project’s aggressive schedule required that the design team complete the majority of the contract plans in only four months, a process that traditionally takes a minimum of one year for a project of this magnitude. As is always the nature of the design-build process, construction efforts began before the design phase was complete. As a result, the design team was required to provide design and post-design services simultaneously with ongoing construction in the field. Some of the post-design resolutions resulted in changes to bridge elements still under design.

Without the connection over St. Louis Bay, residents, commuters, and tourists of the local communities were forced to take a costly, time-consuming, and inconvenient thirty-minute detour around the bay. One of the major overriding objectives of the design-build team was to reconnect the two communities as fast and as safely as possible. In an effort to speed the construction process, all piling, beams, and the majority of the pile bent caps were detailed and constructed as precast elements.

On May 17th, 2007, the new bridge was opened to two lanes of traffic reuniting the two communities of Bay Saint Louis and Pass Christian, setting a record for the largest, fastest, continuously-sustained bridge reconstruction project in the United States.

Project Details

Description Transportation
Disaster Relief
Structural Engineering
Location St. Louis Bay, MS
Client HNTB and Granite/Archer Western
Owner Mississippi Department of Transportation
Awards People’s Choice Award in America’s Transportation Awards

American Association of Highway and Transportation Officials, 2008

Ranked second in Roads & Bridges, Top 10 Bridges, 2007


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