Skip to Content
Streetsblog USA home
Streetsblog USA home
Log In
Boondoggles

Highway Boondoggles 2020: I-526 Extension in S.C.

The I-526 Extension would connect to the James Island Expressway, above. Image: Wikimedia Commons

In this year’s installment of its annual Highway Boondoggles report, U.S. PIRG Education Fund and Frontier Group warn of billions of dollars in proposed spending on unnecessary highway projects that would divide our communities, deprive transit of scarce funds, and pollute our air and water. Below is the fifth of seven installments detailing these harmful projects.

It's our annual December donation drive. Please give from the heart (and wallet!) by clicking here. Thanks.
It's our annual December donation drive. Please give from the heart (and wallet!) by clicking here. Thanks.
It's our annual December donation drive. Please give from the heart (and wallet!) by clicking above or

Charleston County in South Carolina is moving forward with an eight-mile, $725-million extension to I-526 across Johns and James Islands that would, as the Charleston Post and Courier wrote in a 2019 editorial about the project, “create negative environmental and community impacts while providing minimal traffic relief in the immediate term and little or no improvement over the long term.” The so-called Mark Clark extension, which will cost Charleston County more than it has spent on any single project in its history, would be a four-lane parkway from near Citadel Mall in West Ashley to the James Island connector at Folly Road.

The I-526 extension would have minimal impact on travel times. According to a 2016 environmental project re-evaluation, the project would save drivers mere seconds of travel time. Trips to the West Ashley area of the region would be reduced by an average of just 42 seconds, while current travel times are more than 20 minutes. No trips assessed for the project’s Recommended Preferred Alternative would reduce travelers’ trip times by more than 9 percent on average.

The $725-million extension to I-526.
The $725-million extension to I-526.
The $725-million extension to I-526.

The project would, however, have significant negative impacts on the communities it is meant to serve. In the same 2016 reevaluation, the South Carolina Department of Transportation (SCDOT) and Charleston County wrote that their preferred alternative option for the extension would cut through four communities and pass alongside 13 communities, forcing relocations of 15 residences, four businesses, and one community facility.  South Carolinians living along the route are worried about these impacts, with the Post and Courier writing that residents of Johns Island argue it will bring “more residential development” and “urban sprawl” to a place that has already seen “quiet woodlands ... replaced by rooftops.”

Finally, the new roadway would damage the wetlands and floodplains of Johns and James Islands. The islands are coastal, and the communities living on them value their natural resources highly and want to protect them. But the SCDOT and Charleston County evaluation of the preferred route found that the construction of the road will require filling in 26 acres of wetland, shading 43 acres and impacting 346 acres of floodplain. The roadway would also impact three parks and wildlife refuges: the James Island County Park, the West Ashley Greenway, and the Fenwick Hall Historic District.

Stay in touch

Sign up for our free newsletter

More from Streetsblog USA

Report: Traffic Injuries Increase Near Amazon Last-Mile Warehouses

Injuries are increasing near last-mile warehouses and advocates want to change the model for more accountability.

November 18, 2025

Breaking: Trump Admin Seeks To Decimate Federal Transit Funding

"When you're talking about taking away money from transit, your proposal is flawed from the get-go," said one expert.

November 18, 2025

Tuesday’s Headlines Lost the Battle but Won the War

A Politico long read details how bureaucracy slowed down but couldn't stop the conversion to EVs.

November 18, 2025

Report: Biden Infrastructure Bill Spurred Increase in State and Local Highway Spending

The Urban Institute found an overall increase in capital investment in ground transportation — mostly on highways — and flat investment in public transit.

November 17, 2025

Monday’s Headlines Remember

Fifty U.S. cities and others around the globe memorialized the victims of traffic violence on Sunday.

November 17, 2025

Transportation Politics Is Inherently Radical

And we need to embrace that if we want to win.

November 17, 2025
See all posts