NORTH CHARLESTON — When the Don Holt Bridge is demolished, its replacement could be much like the Ravenel Bridge, with eight travel lanes, a bike and pedestrian path on one side, and a height that would allow modern container ships to pass underneath.
One big difference is that instead of one eight-lane bridge, like the Ravenel, the Don Holt could be replaced with a pair of four-lane bridges.
“Two separate structures is what we are considering now," said S.C. Department of Transportation Project Manager Kit Scott.
While plans could change, she said two bridges instead of one could help coordinate the phases of the huge project.
Replacing the bridge across the Cooper River on Interstate 526 between North Charleston and Daniel Island is just part of widening the full extent of the loop to eight lanes from West Ashley to Mount Pleasant.
It's a more than $8 billion project called the Lowcountry Corridor, but that price tag is just a ballpark number that's expected to grow. The project is so large it's been divided in two pieces.
The roughly 10-mile section from the edge of North Charleston on the Cooper River to the end of the expressway in Mount Pleasant, where I-526 transitions into Chuck Dawley Boulevard, is called the Lowcountry Corridor East.
The Lowcountry Corridor East: A roughly $4 billion plan to widen Interstate 526 from North Charleston to Mount Pleasant, a distance of about 10 miles, includes replacing the Don Holt and James B. Edwards bridges. (Source: Esri)
The East project involves replacing two bridges, redesigning the Long Point Road interchange (where trucks access the Wando Welch Terminal) and doubling the travel lanes on the highway — more than half of which is elevated.
When will it happen?
Construction work on the Long Point Road interchange in Mount Pleasant is expected to begin in 2026, Scott said. The rest of Lowcountry Corridor East — including the bridge replacements — is expected to still be going through the federal review and permitting process a decade from now.
“The 2030s, that’s a good as we can (estimate) right now," Scott said.Â
When it's all finished, the results are meant to include improvements in traffic, access to the State Ports Authority's North Charleston Terminal by modern container ships — the main reason the Don Holt will be replaced — and new bike and pedestrian river crossings.
There are some key unknowns about the bridge replacements at this point, including when they will happen, what it will cost and who will pay for it, but existing plans and studies that began years ago fill in many details.
The addition of a bike and pedestrian path on the Don Holt's replacement could offer new opportunities for recreation and exercise to the greater Park Circle area in North Charleston.Â
Pedestrians and bicyclists cross the Arthur Ravenel Jr. Bridge across the Cooper River, between Charleston and Mount Pleasant.
The smaller and shorter James B. Edwards Bridge connecting Mount Pleasant and Daniel Island across the Wando River will also be replaced; paths for bikes and pedestrians are planned there, as well. Â
Exactly where the paths will begin and end, and how they will tie in to existing paths and roads, has not been decided, Scott said.
“The river crossings are the key part, and we’re glad DOT made that commitment," said Katie Zimmerman, executive director of Charleston Moves, a nonprofit group that advocates for cyclists and pedestrians.
She said connecting those paths to a broader bike and pedestrian network will be important to making the paths as useful as possible.Â
The Don Holt Bridge
Few motorists would likely miss the Don Holt, which earned the nickname "Dead Halt" because even minor accidents can practically turn the highway into a parking lot.
Heavy traffic on the Don Holt Bridge on Interstate 526.Â
The bridge, named for a longtime North Charleston state lawmaker, opened in 1992, just 13 years before the Ravenel, literally paving the way for development of Daniel Island and the Cainhoy peninsula. It also created a more direct route to and from South Carolina's largest container port, in Mount Pleasant.
Development and population growth on Daniel Island and in Mount Pleasant would soon overwhelm the bridge and the interstate with traffic. Port-bound trucks often back up down the highway while waiting to exit at Long Point Road.
The number of vehicles crossing the Don Holt daily reached about 86,500 by 2017, and is projected to exceed 146,000 by 2050, according to DOT planning documents. Trucks account for nearly 10 percent of the traffic, largely due to the port.
The DOT already has plans in place for the Long Point interchange, including new ramps for port truck traffic and sound barriers for nearby homes. The fate of the Don Holt was an unsettled question until last month's replacement announcement.
New blue paint on the topside on the Don Holt Bridge on Jan. 30, 2018.Â
A taller bridge is needed in order for modern container ships to reach the North Charleston Terminal, next to the shuttered WestRock paper mill property the SPA is purchasing. On March 26 the DOT committed to building it. Â
"It is our intent to build a taller and wider bridge," incoming DOT Secretary Justin Powell said that day. "You can look at it in a pure dollar perspective, but it adds value to the North Charleston Terminal."
A huge price tag
One thing's for sure: Replacing the Don Holt will cost far more than replacing the Grace and Pearman bridges across the Cooper River with the Ravenel, which at the time was the S.C. Department of Transportation's largest contract ever.Â
That project came in at just over $675 million, which would be $1.07 billion in today's inflation-adjusted dollars. Replacing the Don Holt doesn't have a firm price tag, but it's hovering around double the cost of the Ravenel based on DOT's 2022 Planning and Environmental Linkages study.
The DOT had been considering leaving the Don Holt in place and building another four-lane bridge next to it. Doing so would have saved at least $1.5 billion, the planning documents show, compared to replacing the Don Holt entirely.
Traffic on Interstate 526 goes across the Don Holt Bridge on July 14, 2020, in North Charleston.Â
“With it being a taller structure, it does cost more because it is a more complex structure," said Scott.
The Don Holt has 155 feet of air clearance — the number that limits the height of ships — and its replacement could have 186 feet, the same as the Ravenel Bridge.
Much of the more than $4 billion cost estimate for widening I-526 from Virginia Avenue in North Charleston to Mount Pleasant is due to the bridges and elevated roadways needed for more than half the route.
“The (cost) numbers we have for the (Lowcountry Corridor) East at this time are very general," said Scott.
The James B. Edwards Bridge across the Wando River between Daniel Island and Mount Pleasant will also be replaced with one or two bridges carrying a total of eight lanes of traffic.
While the Don Holt's replacement will be higher, the Edwards Bridge's replacement will be lower. Container ships don't need to fit under that bridge, so its replacement could be 65 feet high rather than the current 138, according to DOT project exhibits. The Coast Guard would ultimately decide.
