Huge Florida Bridge Is on the Road to Ruin : Saltwater is eating away at a seven-mile span that links two islands. Repairs are to begin this summer.

Two summers ago, Jim Perry was sitting in a boat under the Seven Mile Bridge here, hoping to hook a yellowtail snapper on a chunk of cut ballyhoo, when he noticed something that troubled him. The bridge over his head was crumbling.

“Huge chunks of concrete had fallen off the columns. The reinforcing rods inside were exposed and rusting,” said Perry, a 41-year-old golf course foreman. “It was pretty surprising.”

Indeed, two years ago the Seven Mile Bridge was only 7 years old. Built at a cost of $45 million, the span was an instant landmark, the most spectacular link in the scenic 110-mile Overseas Highway that leaps from island to island all the way from the tip of the Florida peninsula to Key West, the southern-most point in the United States.

The bridge replaced a narrow, 80-year-old one-time railroad trestle and was designed to last 40 to 50 years. The bridge is so long that engineers reportedly had to factor in the curvature of the Earth in its construction.

But, as Perry discovered, engineers apparently did not factor in the ravaging effects of saltwater and the porous nature of the limerock mix used in the cement.

Perry, then serving on the county grand jury, reported what he saw. Florida Transportation Secretary Ben Watts climbed into a boat to see for himself. Suddenly, the Seven Mile Bridge was atop the long list of urgent repair jobs. “That bridge is safe,” said the secretary. “But, yeah, we have some problems.”

Later this summer, the first phase of a $1.5-million mission to save the Seven Mile Bridge gets under way when areas of corrosion are “metalized” with a protective zinc spray.

“The corrosion occurred earlier than we anticipated, but it was anticipated,” said Florida Department of Transportation engineer Ken Morefield.

Sadly, crumbling American bridges are not rare. The latest figures from the Federal Highway Administration indicate that about 40% of more than 230,000 U.S. bridges are structurally deficient or functionally obsolete.

But none of the others is seven miles long. Driving across the bridge is like taking your car to sea, sailing at 55 m.p.h. through a pale blue sweep of sky and water separated by the finest of horizon lines. At its midpoint, the roadway arches over a deep-water channel, and from the top of the curve the view seems forever.

The first structures to span the waters between islands in the archipelago were the trestles built by pioneer builder Henry M. Flagler, who extended his Florida East Coast Railway to Key West in 1912. The railroad ran until 1935, when a hurricane with winds estimated at up to 200 m.p.h. ripped through the Middle Keys, tearing up the track, blowing train cars into the Gulf of Mexico and killing more than 400 people.

The railroad died, but Flagler’s bridges, resting on concrete made from crushed New Jersey granite, withstood the storm. Within three years, the roadbed was paved over, and in 1938 the first car pulled into Key West via what was called “The Road That Goes to Sea.”

But the bridges were notoriously narrow and dangerous, and by the 1970s the state decided to spend $200 million to put in 37 new ones. Big Seven, as it was called when it opened in 1982, was the centerpiece.

Ruptures in the roadway were noticed even before the first vehicle roared across, and in 1988 expansion joints between bridge segments were replaced at a cost of $3 million.

But the rusting from within presents the most serious threat.

Near the waterline of many of the 263 concrete pillars supporting the bridge, saltwater has penetrated the porous concrete and eaten through a protective plastic coating around the reinforcing rods. The resulting rust causes the concrete to expand, crack and flake off in chunks, according to Morefield.

Douglas Cathis, president of Metalizing Masters Inc., an Alliance, Ohio, firm that won the $228,800 contract to start repairs, said that a crew would begin to spray liquid zinc onto the damaged concrete and exposed rods sometime around Aug. 1. “The zinc then sacrifices itself to the saltwater attack,” he said.

While under repair--a process that will have to be repeated periodically--the bridge will remain open as usual to an average 8,269 cars a day. And tourists will continue to pull over at either end to fish or snap pictures.

Ken Farrell recalls that during the four years the bridge was under construction, the workers practically lived in his 7 Mile Grill. “I knew them all,” he said, “the ones who built it and the one who died up there. He was drag-racing one day before the side rails were up, and he went right over the edge.”

In the days before the new Seven Mile Bridge--the longest segmental span in the world--was opened, Farrell also remembers truckers asking to borrow brooms to clean the shattered glass out of their cabs. “The old bridge was so narrow that their rear-view mirrors would smash into each other as they passed,” he said. “So we appreciate that bridge a lot. Especially if you remember the old one.”