The beams and girders supporting the eastbound lanes of the Karl S. Bowers Bridge, the oldest of the four spans between Hilton Head Island and the mainland, are deteriorating and need major repairs or replacement, according to a report commissioned by the town and Beaufort County.
The document, completed in February, cites several structural deficiencies in the span's concrete support system. Those include cracks in the pilings, rust and "spalls" -- sections where the bridge's surface concrete has worn off or been knocked off, said Darrin Shoemaker, the town's traffic and transportation engineer.
The other three spans, completed in the 1980s, also have cracks and spalls that need repair, the report said. US 278 Cursory Bridge Inspection
State, county and town officials said the bridge is still safe, and the report said the condition is not unusual, given the age of the bridge, built in 1956.
"This deterioration has potentially reduced some of the structure's capacity but does not impose an immediate risk of failure," the report said.
But town and county officials wonder how long the bridge over Mackays Creek will last. "It is an area of concern," said town manager Steve Riley.
The report was commissioned to find that answer, with the county and town paying $10,000 each for the study. Collins Engineers of Charleston, which the state Department of Transportation has used for bridge inspections, conducted the study.
The report says the bridge has outlived its design life and needs attention in the "near future."
Near future isn't defined in the report.
State, county and town officials agree repairs or replacement will be needed but differ on when that should occur.
HOW MUCH LONGER?
The eastbound section of the Bowers Bridge is 54 years old. It was designed to last 50 years, the report said.
The old span gets heavy use, averaging 44,300 to 57,800 cars each day. This makes it and the other Hilton Head bridges the most-traveled in Beaufort County, the report said. It is exposed to harsh coastal weather, winds and barnacles and other marine life, according to the report.
The westbound lanes of the bridge and the Graves Bridge were built in the early 1980s.
Town and county officials believe the old Bowers Bridge span needs rehabilitation or replacement soon.
"We expect that S.C. DOT will act upon that recommendation as soon as that work can be scheduled," said Shoemaker. "These bridges are supremely important to us."
The town and county's report is an attempt "to begin a dialogue with the owners of that bridge," said Rob McFee, the county's deputy administrator of development and public services.
The DOT "look(s) at a bridge, and they'll say this is in 'good condition,' but they won't really say how much longer it's going to last," McFee said. "We want to know, 'What are you guys going to do with this structure in 10 years?' "
There are no immediate plans to repair or replace the Bowers Bridge, said Curtis Brice, a bridge maintenance engineer with DOT.
"I don't agree that the bridge is in a condition where we need to expedite its replacement," said Brice. The state last looked at the bridge in December 2008, he said.
The urgency of repairs for the Bowers Bridge is ranked against the needs of the state's 9,188 other bridges, and a small number receive repairs each year, according to the availability of state funding, he said. The eastbound span of the Bowers bridge is on the state's list to receive repairs, he said.
"If the DOT had the money to replace every bridge that's that old, they would do it," Brice said.
One out of every five bridges in the state is considered deficient, according to the DOT's website.
But it is also "impossible to predict" when a bridge will need to be replaced, said Brice.
Another DOT bridge engineer, Lee Floyd, had a different view.
It would be "very prudent" for the state to begin planning for the span's replacement or repair, given its advanced age, he said.
But he also said a bridge doesn't necessarily become unsafe when it exceeds its design life.
A bridge has to reach a certain condition before the state will prioritize its repair, Floyd said.
That prioritization is based in part on a federal rating system from zero to 9, he said. When a bridge's rating drops to a 4 or "poor," the DOT will make repair a priority, Floyd said.
The last time the Bowers and Graves bridges were inspected, in December 2008, the three newer spans rated 6, or "satisfactory."
The old span, however, had deteriorated from a satisfactory rating two years earlier to a 4.
The level of deterioration in the 54-year-old eastbound span qualifies it as "structurally deficient," making it eligible for federal funding for repair, Floyd said.
Brendan Byrnes, a spokesman for AAA Carolinas, which rates the state's bridges, believes South Carolina needs to perform more preventive maintenance on bridges.
Making repairs when problems crop up instead of when they become dangerous could save the state money in the long run, he said.
"There are things you can do before problems arise to lengthen the life span of a bridge," Byrnes said.
"It's the same as dental work. It's easier to do maintenance before you get to the gingivitis stage, but once you get to that stage, it takes a lot of discipline to correct the problem."