On July 25, researchers at the University of South Carolina mailed a one-question questionnaire to 5,000 Lowcountry households: “Do you favor or oppose building the extension of the Mark Clark Expressway along this proposed route?” (Half the surveys actually read “oppose or favor,” just to counteract any bias built into the phrasing.)

“This proposed route” referred to a planned add-on to I-526 from the highway’s current terminus in West Ashley to the James Island Connector along a route known as Alternative G, shown on a map enclosed with the survey. In all, 2,189 people responded to the USC survey, and 72.2 percent were in favor of the plan.


The S.C. Department of Transportation has been pushing for Alternative G since an environmental impact study released in July 2010 found that, of the Alternatives A-G that were on the table at the time, G had the lowest cost, lowest number of properties that would have to be relocated, and lowest number of people who would hear a noticeable increase in road noise.

Why extend I-526 in the first place? In 2010, the SCDOT predicted that congestion in West Ashley, Johns Island, and James Island was going to increase between then and 2035 (see more about that in our infograph).


But Dana Beach, executive director of the Coastal Conservation League, says the I-526 extension could have unintended consequences, including increased development in rural parts of Johns Island and, as a result — you guessed it — more congestion.

“You can see why people would think, when you say simply, ‘Would you like a new road?’ they think, ‘Empty road, I get to ride on it by myself, sounds like a good idea.’ They don’t think, ‘How much does it cost? What are we not building as a result of this? What are we not repairing as a result of it?’ And they also don’t think about induced traffic because of the road and also induced development,” Beach says.

Length of Trip in 2035 (hr:min:sec)

In the 2010 Draft Environmental Impact Statement for the possible extension of I-526, the SCDOT explained how extending I-526 would affect travel times. According to SCDOT project manager David Kinard, the figures represent average times for all auto trips to and from an area. “The reason for reporting these figures in this way is to report on the cumulative improvement to mobility in these regions,” Kinard said in an e-mail.

Neighborhood w/out extension w/ Alternate G
West Ashley 0:21:24 0:20:48
Johns Island 0:30:12 0:25:36
James Island 0:21:42 0:21:06


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