Tree removal agreement clears the way for replacement of bridge
The 56-year-old Bohicket Creek Bridge's underbelly has patches of rusted,
brittle steel exposed by crumbling concrete. The tides have whittled away at
its support timbers. The bridge is safe for now, but it's on the fast track
for replacement, a state Department of Transportation official said
Wednesday.
The Charleston County Board of Zoning Appeals this week cleared the way for
replacement of the 43-foot-long bridge when it approved a tree loss
mitigation plan. The bridge is part of Bohicket Road, a vital link for
Johns, Kiawah and Seabrook islands.
Bridge construction will begin in September or October and take about a
year. The estimated cost of a 66-foot bridge is between $1.5 million and $4
million. A temporary bridge will be constructed to handle the average daily
traffic of 14,800 vehicles, said Terry Koon, assistant bridge design
engineer.
The board approved a plan that allows for the removal of 14 pines and two
oaks with a combined diameter of 439 inches. Magnolia, live oak and gum
trees with a combined diameter of 880 inches will be preserved. Tree removal
is necessary to build the temporary bridge.
The DOT set a 10-ton weight limit on the bridge because of its structural
deficiencies. Trucks and other vehicles that weigh more than that amount are
required to take a River Road detour route. "Despite the deficiencies, the
bridge is still safe to use for vehicles not exceeding the weight limit,"
Koon said.
The DOT also plans to replace another Bohicket Road bridge that spans
Hoopstick Creek. "Right now we think that one (Hoopstick) will last a little
bit longer. We're doing the one that absolutely needs to be done," Koon
said. The federal government will pay for 80 percent of construction costs
of the Bohicket Creek Bridge. The state will pick up the rest of the tab
with gas tax funds, he said.
Koon said deterioration happens under the bridge deck when saltwater worms
its way into tiny air pockets in inch-thick concrete reinforced with steel
rods. Rust causes the steel to expand, which cracks the concrete. The rust
also makes the steel brittle, he said.
"It's not continuous throughout the bridge," he said. "It's just in certain
sections."
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