The Lowcountry has almost become synonymous with its many picturesque and historic bridges, but across the state, more and more bridges are succumbing to their age and outdated design.
The South Carolina Department of Transportation (SCDOT) is more than halfway into its “Strategic 10-Year Plan” to replace and refurbish the state’s major highways, interstates and bridges. Of the 8,400 bridges in the state, the SCDOT has more than 1,100 bridges labeled as in “poor condition.”
But right now, the SCDOT has only 10 projects listed in the tri-county area, with the earliest project set to begin in 2024. Four projects are slated for future construction in Charleston County, with a fifth set for 2024. Only one project is slated in Berkeley County and four more are slated in Dorchester County.
“The bridges in Charleston are by and large in great shape,” said SCDOT Chief of Staff Justin Powell said. “It really tends to be in the upper part of the state where we see issues.
“As bridges start to age, we have to look at what we need to do next,” Powell added. “Do we need to replace it? Can we do a rehabilitation? Particularly in areas like Charleston when you have historic structures, preservation and rehabilitation tend to be the model.”
Most bridges built in the 1950s and 1960s have an expected lifespan of about 75 years, Powell said. But conditions in South Carolina have exacerbated that aging process.
“During the Eisenhower administration, there was a national influx of funding for roads, but in South Carolina, we went on a bridge-building boom,” Powell said. “A lot of those bridges are now approaching 60- to 70-years old, so a big part of the challenge we have is that these bridges are just hitting their points at which age is starting to cause issues.
With economic development and rapid growth throughout the state, the quantity and weight of cargo transported along interstates and highways and across bridges has surpassed what most older bridges were designed to support.
“All that growth coming from Charleston, for example, means much more freight moving in and out of the state due to economic development projects,” Powell said. “We have a lot of bridges that are hitting points where you have to look at doing a major rehabilitation or replacement.”
What’s being done?
Being labeled structurally deficient doesn’t necessarily mean a bridge is unsafe — every bridge in the state is inspected every two years for safety. But it does mean it falls short in at least one of several criteria: deck (the surface of the bridge), superstructure (which stabilizes and supports the deck), substructure (smaller support elements) or culverts (the buried portion of the support structure).
Historically, the SCDOT was funded predominantly by the gas tax and money from the federal government, Powell said. This meant much of the funding trickled in and the work trickled out swiftly.
“The discussion of added funding starting in 2016 and 2017 ultimately culminated in doubling the amount of state funding coming into the SCDOT,” Powell said. “What that really prompted us to do was change our way of thinking from, ‘Hey lets add this here,’ to moving toward a process of looking at what outcomes we want to achieve over time.”
The SCDOT immediately began setting goals for investing funds at multiple levels through the 10-year plan. There were four key areas highlighted — pavement, rural road safety, the interstate system and bridges.
Halfway through the 10-year plan, Powell said, the SCDOT expanded its original target of 465 repaired bridges to 500 — 199 have already been completed, and 75 more are under construction, including the 10 in the tri-county area.
“We are seeing continued progress across South Carolina in all areas in improving our transportation system,” Secretary of Transportation Christy Hall said in a June 2022 press release. “The 10-year plan has projects in all of South Carolina’s 46 counties and allowed SCDOT to more than triple its construction program from approximately $1 billion in 2014 to $3.5 billion [in 2022].”
Prevention over replacement
As the SCDOT moves toward the end of the 10-year plan, Powell said, it intends to transition more to a preventive focus, rather than full replacements and bridge closures.
Part of the process is standard, such as the two-year inspections. If the bridge is deemed unsafe, it is immediately closed for repairs and reopened as soon as possible. In Charleston, the SCDOT has a specific unit which conducts these inspections and repairs.
“We have 8,400 bridges across our state, and a small percentage have a small posting and closure on them, but our real task right now is focused very heavily on making sure we don’t have a problem,” Powell said. “We want to have those facilities continue to move uninterrupted,” Powell said. “Right now, we’re really pivoting to trying to get ahead of it.”
And, the SCDOT is slated to get some much-needed funding from the White House.
The Biden administration said it is providing more than $5 billion to South Carolina for road work. Most of that was already heading to the SCDOT’s budget under prior federal law, but the new Bipartisan Infrastructure Law increases federal highway aid flowing directly to the DOT by $250 million or so annually, from roughly $735 million to $1 billion yearly, through 2026. Powell said that increase is going directly to bridges on the state’s major freight corridors.
The new bill is also set to modernize bridges to withstand the effects of climate change and natural disasters.
“When we build a bridge today, we are looking at, particularly in the Charleston area, large earthquakes, hydraulic flow during flood events and more,” Powell said. “We build bridges that are very sturdy and able to handle those pressures and modern truck loads. We don’t go in and replace the same bridge, we make sure it’s being done to address the needs of what we have today.”
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