Frequently Asked Questions

+ What happened to the Mark Clark Expressway Completion Project?

A Draft Environmental Impact Statement (DEIS) for the Mark Clark Expressway was signed in July 2010. The project was then put on hold and revived again in late 2018. Since the signature of the 2010 DEIS, changes to land use, traffic, and demographics have occurred within the study area; therefore, SCDOT and FHWA determined that a Supplemental Environmental Impact Statement (SEIS) was necessary to address the environmental impacts. The Mark Clark Expressway project is continuing under the Mark Clark Extension title now.

+ What is a Supplemental Environmental Impact Statement (SEIS)?

The Federal Highway Administration (FHWA) requires an SEIS when it has determined that changes have occurred in either the project’s concept or affected environment that may render the original environmental analysis no longer valid. An SEIS does not have a specific required format, however, it must include the reason for preparing the supplement in addition to an evaluation of the changes and new impacts. The SEIS follows the same process as an EIS except that there is no requirement for a formal scoping meeting. For more information on the project development or environmental review process, visit our project process page.

+ A lot of growth and development has happened since the original studies were done. Will you be taking that into consideration?

As part of the SEIS, the environmental studies will be updated to include an analysis of potential impacts that may result from the construction of the extension. Additionally, traffic modeling will be updated to incorporate the most recent regional traffic model, which includes new population and growth forecasts, and considers recently completed and committed projects in the study area.

+ How is what you’re doing in 2021 different than before? What is the process for moving the project forward?

The project team is currently working on a SEIS. This will follow a similar process as the previous work, except it will not include scoping meetings. For more information, visit our project process page.

+ Will the “The New Way To Work” alternative be considered in the EIS?

The National Environmental Policy Act (NEPA) requires alternatives to be considered in the EIS. The alternatives evaluated in the SEIS included: (1) No-build; (2) Transportation System Management (TSM); (3) alternative modes of transportation, such as mass transit and (4) build alternatives, including improvements to existing roads and one or more new location alternatives. The range of alternatives investigated in the SEIS are the same 39 alternatives evaluated in the 2010 DEIS, which were based upon input from agencies and the public during the initial coordination and scoping period and subsequent agency and public involvement opportunities.

+ Is there a map available that shows the projected path of the extended Mark Clark Expressway alignment?

Maps of the potential alignment from the 2021 Public Hearing are posted to the project website and are now available in the documents archive. SCDOT’s Recommended Preferred Alternative was identified as Alternative G.

+ What is the predicted path the new road will take?

The preferred pathway for the Mark Clark Extension was determined after the current studies, evaluations, and an alternative analysis was completed for the 39 reasonable alternatives. The SEIS re-evaluated the range of alternatives to determine the reasonable alternatives that were further evaluated in the SEIS. The SEIS identified SCDOT’s Recommended Preferred Alternative as Alternative G.

+ How will the new road impact neighborhoods in its path?

SCDOT, in partnership with Charleston County, has embarked upon a SEIS which re-evaluated the range of alternatives. When SCDOT released the SEIS, a process that includes the evaluation of alternatives and comparison of impacts on both the natural and human environment, impacts to both the natural and human environment will have been and will continue to be avoided and minimized to the greatest extent possible.

+ How is this project being funded?

In November 2004, the voters of Charleston County approved a half-cent sales tax for transportation, public transportation and greenbelt projects in the county. To complete the plan for Mark Clark Expressway, Charleston County officials used these sales tax transportation projects as a local match to apply for funding from the South Carolina Transportation Infrastructure Bank (SIB) in 2006. Upon review of the application and the availability of matching funds, the State Infrastructure Bank (SIB) committed to fund the project. However, in June 2018, the SIB voted to deny funds for the Mark Clark Expressway citing concerns surrounding Charleston County’s ability to secure the additional funds needed to cover the project costs (above that provided by the SIB). In January 2019, Charleston County Council voted to approve a new plan, with the county paying for approximately $305 million for the project. This was followed by approval by the SIB to provide $420 million to complete the Mark Clark Expressway. In February 2019, Charleston County Council voted to use approximately $3 million from the transportation half-cent sales tax to fund the Mark Clark Extension project for 2019. Further, the County approved the 2020 budget that includes an additional $8.5 million for the project.

+ What is the status of consultation under Section 106 of the NHPA?

The Section 106 review and compliance for the Mark Clark Extension begins with SCDOT coordinating with the South Carolina State Historic Preservation Office (SHPO) and conducting public meetings to identify historic resources within the potential area of effect for this project. In addition to consultation with SHPO, SCDOT will coordinate with all local, state, tribal, and federal agencies, and the public to identify consulting parties throughout the length of the environmental review process. The coordination and involvement initiatives for the 2010 DEIS began with a public scoping meeting held April 10, 2008 and an agency scoping meeting held April 29, 2008. Coordination initiatives continued with public meetings held in November/December 2008 and April/May 2009. Additionally, coordination meetings were held with SHPO and consulting parties to assess historic resources and identify potential impacts by the project. The results of the historic resources survey and details concerning coordination meetings were included in the 2010 DEIS which can be found in the documents archives. As part of the 2021 SEIS, coordination efforts will continue.

+ Will traffic and safety issues associated with Johns Island and James Island be addressed in a comprehensive way?

Yes; as part of the Supplemental Environmental Impact Statement (SEIS), a comprehensive traffic analysis was conducted using the BCDCOG travel demand model as the basis. This model was updated using the most recently updated land use plans, including the Johns Island Plan by the City of Charleston and the recently updated Comprehensive Plan for Charleston County. All recently completed transportation improvement projects in the project study area were incorporated as well. This includes work conducted within the City of Charleston, Town of James Island, and Charleston County and other surrounding municipalities. This traffic analysis was both a regional traffic analysis as well as a detailed traffic engineering exercise at and near proposed interchanges.

+ How is the county going to address traffic on Johns Island roads (Bohicket, Main, Maybank and River Roads)?

Charleston County is currently working on projects to improve traffic on Johns Island such as Maybank Highway Improvements and the Main Road Corridor. For more information on these projects, you can visit the County website. For a full listing of existing and committed projects in the region, click here to our Existing + Committed projects map or visit SCDOT’s Project Portal.

+ Will the Mark Clark Extension provide a long-term solution or just move congestion around?

It is the goal of all transportation projects to improve mobility. In the case of the proposed Mark Clark Extension, the level of improvement provided by the proposed facility will be evaluated as part of the SEIS. The traffic analysis will be conducted to a forecast year of 2050 for the evaluation of the performance of the project.

+ How do I add my name to the email information distribution list?

To add your contact information to the email distribution list, please subscribe on our Get Involved page.

+ How can I comment on the project?

While the Public Hearing comment period for the SEIS closed on October 15, 2021, You can comment on the project anytime on our Get Involved page. Additionally, comments may be mailed to: Jae H. Mattox, III, P.E. SCDOT Project Manager P.O. Box 191 Columbia, SC 29202-0191, or emailed to info@scdotmarkclark.com .

+ Is there any additional information available? Where can I get more information about the project?

SCDOT will continue to update the website with information about the project as it continues. The Public Hearing took place August 18 through October 15, 2021. Newsletters have been distributed through email or mail and will be sent to those who have asked to be on the project distribution list. Newsletter content is available on the project website. To sign up for the newsletter, go to our Get Involved page. The 2010 DEIS is available in our documents archive.