Hurricane Ivan struck Pensacola, Fla., during the night of Thursday, Sept. 16, 2004, and on into the early morning hours of Friday. It was the third of four hurricanes to hit Florida in the 2004 season. The Category 4 hurricane heavily damaged the Interstate 10 Bridge spanning Escambia Bay, and loss of the bridge meant that traffic had to detour 130 miles out of its way.

By mid-morning the next day — even before the waters receded — Florida Department of Transportation (FDOT) engineers were looking at bridge images, trying to estimate the work necessary to restore at least half the bridge.

Fortuitously, in the spring of 2004 a team of U.S. bridge engineers had visited Japan, Netherlands, Belgium, Germany, and France on a scan trip sponsored by the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA). The trip focused on prefabricated bridge elements and systems. William Nickas was part of the team and saw first hand how heavy lifting contractors employed specialized systems like self-propelled modular trailers (SPMTs) to move major structures. The FDOT's Request for Proposals (RFP) identified skidding, sliding and lifting expectations for use in the emergency design-build reconstruction project.

FDOT called in four contractors to meet with construction personnel. All the contractors immediately sent people to Pensacola to take a first-hand look at the damage. What they saw were washed-out approaches, missing expansion joints, misalignment of numerous spans, missing spans, and debris everywhere.

Much of the bridge's superstructure consists of low-level, precast, prestressed spans supported by six girders. The spans are 60 feet long and 35 feet wide, and each weighs about 235 tons. The low-member elevation off the water is about 12 feet, but the bridge rises to a level of 55 feet above the water for ship navigation. The bridge length is 13,596 feet.

Generally, large waves from storms that strike the Florida coast dissipate when they reach the continental shelf. The distance between the beginning of the shelf and the coast is relatively short, so the wave doesn't have sufficient time to redevelop. But the shelf off Pensacola is wider, so the Hurricane Ivan waves regained strength as they approached the coast and gained even further strength with the high tides and storm surge inflicted on Pensacola Bay, according to Dr. Max Shepard of the University of Florida and Rick Renna, state drainage engineer of the FDOT.

By the time the surge struck the bridge structure, it reached points near the top of the deck, trapping air between the girders and generating a massive uplift. The uplifting forces on the superstructure created a great deal of tension on the eight anchor bolts holding each span in place. Many anchor bolts failed, and then pounding wave action from the side displaced numerous spans laterally.

Some spans displaced the width of one or two girders of the six supporting the spans, creating severe misalignments. Forty-six spans on the eastbound bridge displaced more than three girders, and were sufficiently out of balance to topple over into the water. Twelve spans toppled over on the westbound side. Fifty eastbound spans and 16 westbound suffered misalignment.

The FDOT RFP anticipated substituting spans from the most heavily damaged (eastbound) bridge onto the westbound bridge, and building on steel foundations. For the purpose of speed, FDOT waived durability requirements and specified systems that are "off the shelf." Steel was the natural choice for any new substructures required in this high-priority project. The department planned to use existing prefabricated Acrow steel bridge components to repair the more heavily damaged eastbound side until a new bridge or replacement components could be designed and built.

Before the actual extent of the damage was known, FDOT asked contractors to bid on 14 days for Phase 1 (repairing the westbound lanes) and 90 days for Phase 2 (the eastbound lanes). The state established a $50,000 a day incentive as the bonus early in the morning in an attempt to get things moving quickly.

As discussions continued throughout Friday morning and beyond, the receding waters revealed substantially more substructure damage than originally anticipated. As the superstructure moved laterally, often at an angle to the bridge, it had twisted and dragged piers down with it.

FDOT revised the time to repair the eastbound side to 24 days. But the $50,000 per day bonus and/or penalty was not sufficient for contractors to expedite repairs since they tended to incorporate delay penalties in their bids.

To overcome this hurdle, FDOT top management approved a $250,000/day bonus/penalty with a cap of $3 million to maximize motivation. That broke the log jam, with one contractor bowing out and others joining forces. The remaining two contractors continued to work with their designers throughout the afternoon. They met with FDOT for a final question and answer session in late afternoon. Then they turned in their bids at 9:30 that Friday evening.

The approach by a joint venture of Gilbert Southern of Nebraska and Massman Construction of Missouri, aided by the Parsons Transportation Group as a consultant, included a proposal to delay removal of the submerged slabs until the second phase. Instead, they proposed to drive steel piles through the existing submerged spans, leaving them under water. They planned to straddle the existing piers and any obstructing sections of concrete spans. The goal was to expedite the effort towards completion of Phase 1 to qualify for additional bonus. This would quickly get traffic rolling. They'd figure out later how to remove the submerged concrete.

This outboard pier design created high bending moments, which required a new substructure with larger, heavier steel cap and pipe piles of greater thickness. But the extra money for material would be more than offset by the greater speed and bonus for completing Phase 1.

Tough negotiations under a great deal of pressure continued throughout Friday evening on contingencies for this approach. At one point everybody had to take a break and go for a walk. But by midnight FDOT and Gilbert/Massman struck a deal, with both parties signing the emergency contract for $26.4 million, including both the eastbound and westbound lanes. The Phase 1 deadline was 24 days with a $250,000/day bonus/penalty. The Phase 2 deadline was 90 days with a $50,000/day bonus/penalty. The clock began to tick at midnight.

By Saturday morning, contractors began to order materials and mobilize workers. Consultant construction administration of Volkert & Associates also arrived at the site. The joint venture mobilized 40 welders from offshore platforms from a sister company, Kiewit Off Shore (KOS), for welding new substructure components. This decision brought in the talent to quickly fabricate piling which jump started the urgent project. They would work 12-hour shifts around the clock.

Since the region was devastated by the hurricane, nearby hotels and restaurants were without power. So aside from construction supplies, contractors rented generators to power up local establishments and shipped in Winnebago-like vehicles and campers to serve as living quarters.

They also mobilized Massman's 600-ton floating crane, which had been scheduled for work with the Louisiana DOT. LDOT postponed its contract to help with Florida's recovery efforts. This crane — few of which are available in the United States — can pick up a 300-plus-ton load 100 feet away from its center pivot.

Neighboring states granted permits for oversize widths and loads for piling and other supplies. For the new substructures, contractors ordered 36-inch pipe pile with 3/4-inch wall thickness since they knew it would handle any situation they encountered.

To expedite approval of engineering calculations and drawings, FDOT committed to a four-hour turnaround 24/7 until traffic was under way on completion of Phase 1. This meant that FDOT engineers performed calculations and checked submittals continuously in a nearby conference room as the Gilbert/Massman/Parsons team developed plans and submitted them for approval.

By Sunday, heavy equipment began to appear on the site. Contractors were identifying subcontractors and dive teams. On Wednesday, welding began on the pipe piles, which came in by truck in the form of 40-foot sections. For Phase 1, the team had to build seven new substructures consisting of 28 pilings, each of which was 160 feet long.

The contractor also identified and purchased 36-inch steel roll beams from a disassembled bridge in Tennessee, got the mill certifications from Tennessee DOT for them, and shipped them to the job site for use in Phase 1 substructures.

In addition to the new substructures, the contractor had to realign 16 spans on the westbound bridge and substitute 12 superstructure spans taken from the eastbound bridge. After six days of preparation, Barnhart Crane & Rigging was ready to move the misaligned spans back into position. Workers jacked the spans up and placed Teflon pads underneath the beams. They used a combination of techniques to straighten and slide the spans back into position, including horizontal hydraulic jacks, tugs and barges, Goldhofer hydraulic platform trailers, and a custom skidding system.

By day eight, additional cranes arrived to help with the debris removal and clean up. Pile welding continued. By day 10, the welding operation ceased to be critical; two days later, the contractor had driven nearly all the new piles for the westbound substructure. Work began on the approaches.

The 600-ton crane finally arrived on the job site on day 11, somewhat delayed by a resurgence of Hurricane Ivan. By the next day workers had put the crane together, and it was ready for work. Its first job was to overcome the challenge of picking one of the submerged westbound spans out of the water in preparation for a replacement with an eastbound span. This was the only submerged span removed of the 12 on the westbound side.

On day 13, with the help of a specialized hydraulic Goldhofer trailer on a barge, span 43 on the eastbound side was lifted and removed. Workers strapped it to the barge, and tugboats pushed the barge around to the westbound side and set it into Span 61 WB. The barge floated the span to the only gap on the west side of the navigation channel. Once workers slid the span into place, it created a completed bridge two-thirds of the length on the westbound side. Traffic control stripping and delineators could now be installed on the deck.

On day 15 workers' final activities were being completed for the new substructures. In this configuration four new piles frame the original substructure, sitting outside its original footprint. Two 36-inch-deep rolled steel beams serve as the steel caps on each side of the old substructure.

On day 16, crews moved the 600-ton crane to the east side of the high-level bridge section in position to begin placing its 11 missing westbound spans. The contractor chose locations from which the crane could set two spans without the need to move to a new position. The barges began delivering a span taken from the eastbound lanes every two hours. Surprisingly, the contractor managed to replace five spans on that first day of span relocations.

On day 17, Oct. 4, the crane set the remaining seven spans into place. The last span was in position at 11:30 p.m. — seven days ahead of the bonus/penalty deadline. This qualified the contractor for a $1.75-million bonus. By 6 a.m. the next morning one lane of traffic started rolling across the repaired section of the bridge in both directions. Governor Jeb Bush, U.S. Secretary of Transportation Norman Mineta, several FHWA dignitaries, and representatives from FDOT and Gilbert/Massman were on hand for a ceremony to reopen one of the twin structures.

Phase 2 called for the contractor to repair the eastbound bridge with existing spans and steel Acrow sections within 90 days of the signing. The original plan was to create alternating existing spans consisting of 60 feet of concrete and an open 60-foot hole. A total of 7,000 feet of prefabricated Acrow bridge system would span across the entire alternating concrete/gap system of the bridge. This FDOT concept would provide sufficient area to slide in spans if replacement/repair was feasible. It also eliminated the necessity for custom steel work since the Acrow system would be allowed to "float across" and not be abutted at each end.

But the contractor recommended special end panel hardware and truss panels to permit connection of the steel Acrow superstructure directly to the piers. FDOT eventually accepted this option, which shortened the prefabricated steel section to a total of 3,480 feet (58 missing spans by 60 feet long), saving money and time. But it precluded sliding in new concrete underneath the Acrow steel system in the event it was more cost effective to repair this bridge rather than replace it. Engineering studies later ruled out repairing the bridge, making complete replacement necessary sometime in the future.

FDOT owns more than 10,000 feet of Acrow and Mabry modular bridge components, which are stored in a location near Orlando. In preparation for Phase 2, FDOT contracted for 250 truckloads of these components to start shipping to the job site. The parts started arriving at site on day 6 and continued over the course of 20 days in lots of 12 to 16 loads a day. The trucks essentially brought in steel components — bundles of bolts, frames, trusses, and floor beams — that had to be assembled. Assembly began about mid-way into the completion of Phase 1.

Following completion of Phase 1, crews continued working on the eastbound side, aligning and straightening spans and setting up to remove 46 submerged spans. Removing them was a challenge, but the team had previously removed Span 61 westbound and had new ideas to gain efficiency. Many were buried in mud. Divers constantly in the water helped with the rigging. Crane operators had to be careful when lifting the spans that nothing fell on the moving traffic on the eastbound side. Some 104 new piling and a total of 26 steel bent caps were replaced, the contractor opting to replace rather than repair several bents in phase 2 to improve efficiencies.

Since the width of the span is about 24 feet, FDOT set up one lane of traffic. This configuration was selected because of the anticipated long period of service. The Acrow spans weighed 50,000 pounds without the deck, which adds another 10,000 pounds.

By day 56 the contractor was getting ready to set the last of the Acrow steel spans. Work began on the approaches while welders continued to build expansion assemblies for the Acrow system.

On day 65, 26 days ahead of schedule, the contractor completed the two Acrow bridge sections — one on each side of the elevated bridge at the navigation channel. By beating the 90-day deadline, the contractor qualified for the maximum Phase 2 bonus of $1.1 million. Phase 2 crews had erected a total of 3,640 feet of Acrow steel bridge and built 26 new substructures for the eastbound lanes. Both the eastbound and westbound lanes opened before Thanksgiving, which always begins a heavy Florida traffic season.

The repair used about 3.9 million pounds of new steel for piles and substructures. The Acrow bridge system weighs about a 1,000 pounds per linear foot, adding about 3.5 million pounds of steel in the eastbound superstructures. Cost of the repair, including bonuses, was roughly $9.7 million for the westbound lanes and $21 million for heavily damaged eastbound side.

FDOT expects the replacement bridge will cost about $325 million including design, construction and CEI services. The replacement contract will be advertised under a design-build contract. There will be a milestone bonus to open at least four lanes of the new bridge in December of 2006.