It happened around 11:40 a.m. near mile marker 16.
Officers say Linda Overstreet, 51, of Germantown, Md., had apparently ran off the roadway on the ramp to I-81, and then flipped over.
Deputy T. Funk with the Berkeley County Sheriff's Office had discovered the vehicle on its top, and Overstreet lying outside on the ground. She was taken to the hospital for her injuries.
The Berkeley County Sheriff's Office and Fire and Rescue were on the scene to handle the crash.
The cause is still under investigation.