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U.S. 90 Bridge over Biloxi Bay

US 90 Bridge over Biloxi Bay

U.S. 90 Bridge Over Biloxi Bay - Biloxi, Mississippi

Hurricane Katrina

Hurricane Katrina, one of the deadliest and costliest natural disasters in U.S. history, made landfall on August 29, 2005, devastating the Gulf Coast. The U.S. 90 Bridge over Biloxi Bay—connecting the communities of Biloxi and Ocean Springs, Mississippi—was one of many major highway and railroad bridges knocked out of service due to extensive storm damage.

The eye of the storm passed 60 miles west of Biloxi. Peak wind gusts of up to 100 miles per hour, a peak storm surge height of 22 feet, and waves of up to 8 feet roared through the bay. Overall, spans that had a soffit elevation of 23 feet or less were badly damaged, and many of the low-level superstructure units were thrown off of the pile caps and into the water—some of the units were even flipped upside down.

The original bridge consisted of low-level approach spans with a bascule navigation span. The Mississippi Department of Transportation (MDOT) and the Federal Highway Administration (FHWA) elected to replace it with a new high-level bridge using the design-build project delivery method, which allows design, engineering, permitting, and construction activities to be conducted simultaneously. A relatively new concept for MDOT, the design-build project delivery method is essential for a fast-track project.

MDOT awarded the contract to rebuild the bridge to GC Constructors (GCC) and its subcontractor, Parsons. A critical factor in MDOT’s selection of GCC was the team’s technical score: GCC received the highest technical score on the proposal.

Design and Construction Support

As Lead Design Engineer, Parsons was responsible for the design and construction support for the bay bridges, CSX Railroad bridges, and approach roadways. In just 18 months from notice to proceed, the bridge was required to have one lane open to traffic in each direction, and the entire project was required to be complete in just 22 months. The first bridge was opened to one lane of traffic in each direction 2 weeks ahead of schedule, and the entire project was completed in 20½ months—1½ months ahead of schedule. In addition, the Parsons-led design team completed 90% of the design work within just 6 months. The use of precast construction and the development of an assembly-line production approach for both design and construction work combined to deliver this emergency reconstruction project in record time and with a high degree of quality.


This fast-track, $339 million, design-build contract presented three major challenges:

  • Because this was a post-hurricane design-build project, underwater debris and pieces of the old bridge were in the way. In an effort to rebuild as quickly as possible, design had to circumvent the debris field and allow the contractor to come in and start working. Debris and pilings were removed from the old bridge later.
  • The massive reconstruction efforts along the Gulf Coast following the hurricane produced an overwhelming demand on the precast industry and represented a significant supply and schedule risk for this project. Therefore, the design was developed to diversify the required precast piling and girders and to minimize the specialty products that only a few precastors are capable of producing. This technique provided GCC with significant redundancy in potential suppliers during construction if a specific precastor could not deliver products according to the required schedule.
  • The Parsons-led design team was tasked with developing an economical approach to pier and foundation construction that addressed the wide range in geometric and loading conditions. The piers vary in height from 6 to 90 feet. The goal was to develop a design that could be built using an assembly-line approach that minimizes variability in formwork and equipment.
Photo of the pier construction

Pier Construction

Dual Structures, Three Lanes of Traffic Each

The new bridge consists of dual structures, each carrying three lanes of traffic. The eastbound bridge also has a 12-foot shared use path. The total width is 129 feet. Aesthetics were an important consideration in the design development. Because of the adjacent communities’ desire for an attractive structure, the fascia girders are colored blue-green using a concrete coating, and the formed concrete surfaces of the superstructures and substructures are colored antique ivory. The pedestrian railing along the shared use path is an ornamental aluminum picket railing. In addition, three overlooks are spaced along the path with a bench located at each. The outside traffic barriers are an open concrete barrier rather than the traditional, solid New Jersey configuration. At night, the bridge is illuminated with a string of ornamental necklace lights attached to the fascia girders and edge accent lights on the piers.

The bridge was also designed to withstand hurricane-force winds and waves similar to those of Katrina. In fact, we made two design provisions to increase the future safety and reliability of the bridge during hurricane events:

  • Above critical wave height: Parsons maximized the length of the bridge’s superstructure above the critical wave height. Steep 6% grades are now designed into each end of the bridge to raise it above the critical height as soon as possible.
  • Below critical wave height: For the portion of the superstructure below the critical wave height, Parsons designed concrete restrainer blocks on top of the piers and between the girders to prevent the superstructure from being pushed off its supporting piers when subjected to waves.

Approximately 35,000 cars per day crossed the four-lane bridge between Biloxi and Ocean Springs before the hurricane damaged it. The loss of the bridge created a significant hardship and mobility issues for the surrounding communities: the detour route required an additional 30 minutes to what was normally a 1-minute commute.

Biloxi bay bridge illuminated at night

Illuminated Biloxi Bay Bridge

Innovative Management Award

The opening of the bridge marked a milestone in the Gulf Coast’s recovery from Hurricane Katrina. Parsons’ efforts on this project restored a critical connection between the communities of Biloxi and Ocean Springs, reviving the economic vitality of the Mississippi Gulf Coast and helping its residents get their lives back to normal. Parsons performed its work ahead of schedule and developed a design that supported the contractor in delivering the project on budget. This success demonstrated Parsons’ ability to deliver complex technical and management solutions while providing value to its clients and service to the community.

This project, which received the Innovative Management Award in the large project category from the Southeastern Association of State Highway and Transportation Officials, is an excellent example of how design-build delivery, precast construction, and a great deal of hard work and cooperation among all parties involved can result in the successful fast-track delivery of major transportation projects.

A veteran in transportation services, Parsons has worked on more than 4,500 bridges of all types in more than 40 countries on six continents.