New documents released by transportation officials Thursday shows they were aware since at least 2010 of the dangerous potential for corrosion along a Lowcountry bridge eventually shut down due to a snapped cable.
However, problems with staff turnover and uncertainty about how to fix the issues on a relatively young, expensive James Edwards Bridge plagued Department of Transportation engineers. The 1990 structure along Interstate 526 is the primary route north out of Mount Pleasant.
The Post and Courier reports that state officials knew for a long time that leaky joints and corrosion posed a threat to the structure’s integrity which has been plagued with problems almost since its opening in 1990.
Deputy Engineering Secretary Leland Colvin said the bridge’s unusual segmented design is partially to blame. “Florida has over 100 bridges of very similar design as ours,” he told reporters during a briefing Thursday as the agency released the documents. “Many of those are experiencing corrosion, as well as failed cables within their bridges. This is not something that is uncommon for this type of design.
Colvin said engineers believe water has been seeping through construction joints to get into cable “tendons” which help support the bridge. He said the water corroded the steel, a concern inspectors cited as far back as 2010. Inspectors eventually switched to weekly inspections (rather than the usual biannual checkups for a bridge) out of concern.
Inspectors discovered the ruptured cable during one such inspection last month. SCDOT immediately closed the bridge to all traffic until the massive cable could be replaced. The agency initially predicted a June 11 opening date, but indicated Thursday it has finished emergency repairs and could reopen the structure at 8 a.m. Saturday.
Transportation Secretary Christy Hall said crews also worked to repair the joints and plan to eventually resurface the bridge.
The bridge’s design has also led to difficulties with inspections. Colvin said, even though inspectors have been aware of the potential for corrosion, the duct work is
“That is a seven-foot wide concrete diaphragm,” he said. “And, once you get into those boxes, it is very difficult if not impossible to really ascertain the condition of the cables.”
He said the broken support cable has been replaced with two new ones. Once permanent repairs are made, the bridge will have ten cable tendons across its span rather than the current eight. The agency said there is no timeline in place to make those changes at this time.