SCDOT, Charleston County, FHWA announce Mark Clark Extension Project underway

The South Carolina Department of Transportation (SCDOT), Charleston County, and the Federal Highway Administration (FHWA), have re-initiated work on the Mark Clark Extension project (formerly known as the Mark Clark Expressway) in the form of a Supplemental Draft Environmental Impact Statement (SEIS). A redesigned website ( is available to provide ongoing updates of the project’s progress including frequently asked questions, history of the project and a form to submit comments.

The Mark Clark Extension project’s purpose is to increase the capacity of the regional transportation system, improve safety, and enhance mobility to and from the West Ashley, Johns Island and James Island areas of the Charleston metropolitan area.

The project includes the proposed construction of approximately seven miles of new roadway from the existing endpoint of Interstate 526 (I-526) at U.S. 17 (Savannah Highway) to the James Island Connector (SC Route 30) at Folly Road in Charleston County.

Since the  Draft Environmental Impact Statement (DEIS) was completed in 2010, changes to land use, traffic, and demographics have occurred within the project study area. SCDOT and FHWA have determined that an SEIS is necessary to evaluate the changes in the project study area and the impact they may have on the project. All 39 alternatives evaluated in the 2010 DEIS will be re-evaluated in the SEIS. New traffic analysis and updated studies to determine potential changes to the human and natural environments within the project study area will be completed for the SEIS.