Allowing two-way, two-lane traffic on Interstate 526 has diverted 20,000 cars daily that had been clogging East Cooper detour routes around a shuttered Wando River bridge, state authorities said Wednesday.
While North Charleston's mayor said the measure has prompted gridlock in his city, South Carolina officials said they had no plans to undo the effort that has eased Mount Pleasant's traffic headaches.
"The two-way traffic ... has worked exactly as expected, and it's improved every day," said Traffic Engineering Director Rob Perry of the S.C. Department of Transportation. "We don’t intend to make any changes."
But the ultimate goal — to get traffic back to normal for everyone — is still on track, the officials said.
They gave a briefing Wednesday from atop the James B. Edwards Bridge as crews assembled the cables being installed to shore up the span. A break in one of the eight main lines that tie together the bridge's many concrete segments was discovered May 14, prompting the span's emergency closure and igniting traffic tie-ups last week in Mount Pleasant.
The cables run from the top of the bridge to the bottom. When the cable broke, a plate that helps anchor it to a wall was ripped free, DOT Deputy Secretary for Engineering Leland Colvin said Wednesday.
But by June 11, the severed cable will be replaced with three new ones, Colvin said. The cables will be put into holes that were drilled when the bridge was built in the late-1980s in case any issues later arose.
Having a combined 10 cables adds a level of safety, Colvin said, for a bridge that has been plagued by corrosion over the years.
"The repairs are going very, very well," Colvin said. "There's been no major concerns ... no issues regarding our schedule."
What caused the cable to snap remains a mystery, though experts have cited corrosion from water intrusion as the cause of damage found in another line in 2016. Preliminary results of testing are expected next week.
Since the discovery two years ago, experts have been inspecting the bridge every week. Those reviews have become daily since the recent failure and will continue after the repairs unless the DOT gets special monitoring equipment to watch for damage. The state had sought federal funding for the same sort of technology in 2002.
But DOT Secretary Christy Hall said the bridge is not doomed.
"I have no concerns ... that this bridge is going to fail," she said.
Colvin on Wednesday pointed to one of five areas where rainwater was seeping into the bridge's hollow interior and running over the cables inside. The break happened at one of these problem spots, each of which rests above the 51 concrete support stanchions under the bridge.
Those five spots will be refilled with concrete, and the rest of the 51 will be resealed to stop the water flow, Colvin said.
"Certainly," he said, "we've got some concern with five of those."
It was not clear whether the DOT had such concerns before the break.
The resulting closure of westbound I-526 diverted the average 70,000 motorists who cross the bridge daily in both directions, forcing them onto two detour routes through Mount Pleasant and Daniel Island. But since Sunday, when new crossover lanes were paved and the eastbound side of the bridge opened to two-way traffic, about 40,000 cars — nearly evenly split between both direction — have crossed the Wando River there every day, Perry said.
While the move boosted speeds on U.S. Highway 17 and Clements Ferry Road in East Cooper, traffic has backed up for miles on eastbound I-526 in North Charleston and slowed to a crawl on Interstate 26.
North Charleston Mayor Keith Summey said the slowdowns from crossover traffic were unfair to residents trying to get to work in the Mount Pleasant area, and he called on the DOT to make eastbound I-526 one-way during the morning rush hour.
The DOT spent hours Wednesday morning addressing the issue with North Charleston officials, Hall said.
But, Perry added, it wouldn't be safe to allow one-way traffic for three hours every morning, then two-way for the rest of the day.
"Clearly," Hall said, "getting this bridge repaired in the most expeditious manner as possible … is the solution for all of us."