Charleston County plans signal, compact traversable roundabout on Fort Johnson Road after repeated crashes

Charleston County public works officials outlined safety-driven redesigns for two Fort Johnson Road intersections on James Island, saying the work includes a full traffic signal at Fort Johnson and Secessionville Road and a compact, traversable roundabout at Fort Johnson and Camp Road.

Sheila Parker of Charleston County public works said the projects "derived from the 2016 transportation sales tax" program and were prompted by a history of crashes: "there's been several accidents uh in the past 10 years. I think upward of 50 uh maybe even more than that," and she said there had been a pedestrian fatality at the Secessionville intersection. "It’s been deemed a very dangerous intersection," she said.

The signalized treatment at Fort Johnson and Secessionville will replace flashing yellow signals and stop signs on the side street with a full-faced traffic signal, new sidewalks and added left-turn lane capacity on Fort Johnson to separate turning vehicles and improve pedestrian crossings. "You'll know, okay, I stop when it's red, I go when it's green," Parker said, describing how signals reduce uncertainty about right-of-way.

At Fort Johnson and Camp Road, public works officials selected a compact roundabout to address poor sight lines and speeding on the Camp approach. John Martin explained the design as a "transversible urban compact roundabout," saying engineers reduced the roundabout footprint to limit tree and right-of-way impacts while making the center traversable so large vehicles such as tractor-trailers and fire apparatus can drive over it when needed.

Officials said they intentionally kept landscaping out of the center island to preserve that traversable surface. "We had to make it traversible for large vehicles," Martin said, noting the traffic study showed such large vehicles are infrequent but must be accommodated.

Both intersections will include drainage improvements to mitigate runoff and to replace aging pipes and drainage boxes, officials said. Parker said many of the existing pipes are DOT-owned and aging, so the projects will replace or augment them as part of the construction.

Officials described a multi-year planning and public-feedback process that considered alternatives and site constraints such as signal warrants, right-of-way and dense utility corridors that include utility poles and water and sewer infrastructure. Doing the two nearby projects together — they are roughly a half-mile apart — saved contractor mobilization and utility-relocation costs and allowed crews to move between sites to keep work on schedule.

On the schedule, public works said substantial completion is targeted "a little over a year from now," contingent on material availability, weather and any unexpected utility issues. Officials also said the Fort Johnson–Secessionville intersection will be fully closed for a period during construction and that the county will implement a detour plan timed for spring break to minimize impacts on school traffic and peak commutes.

Aesthetics and local features will be restored where possible: lighting and modest landscaping are planned at the roundabout, and stone monuments removed for construction will be reinstalled and maintained under a town easement, officials said.

The projects are currently in construction. County officials encouraged residents to review the public meeting materials and detour maps released in February and said they will update the public if schedules change.