Some Charleston County residents over the past few days received in the mail a brief questionnaire on whether they favored the controversial completion of the Mark Clark Expressway across Johns and James islands.

The survey came from the S.C. Department of Transportation, but department officials said Monday they couldn’t answer any questions about it.

Charleston County now has control of the project to finish Interstate 526, but it voted in January to turn it over to the DOT. The department has not agreed to take on the road, however, even though many local elected officials have pushed the issue in recent weeks. If the DOT refuses to take on the project, Charleston County could be on the hook for $11.6 million already spent on it.

The most recent estimate to complete the project is $556 million, but only $420 million currently is available for it.

Elected officials who support the project said at a news conference earlier this month that before the DOT would take over the road, it needed to know there was money available for it and that it had widespread community support.

Supporters of the I-526 project say it is essential to relieve severe traffic congestion in the growing region, improve hurricane-evacuation routes and link local communities.

Opponents say the project will promote urban sprawl, and that other local road projects are more important to the area than I-526.

The DOT’s questionnaire asked selected residents if they favored the completion of Interstate 526, as well as their age, race and gender. And it asked residents to return their responses by Aug. 21 to the University of South Carolina’s Institute for Public Service and Policy Research.

DOT spokesman Peter Poore said Monday that the department couldn’t answer questions from The Post and Courier until today. A USC professor involved in the project couldn’t be reached until then, Poore said, and DOT officials couldn’t respond without that person’s input.

The newspaper had asked the DOT:

Why it sent the questionnaire.

How many homes received it.

Why it asked particular questions.

What the department would do with the information it gathered.

How much the survey would cost, and who was paying for it.

Whether the information obtained would help the DOT decide whether it would take over the project from Charleston County.

James Island resident Jenny Welch received one. She’ll return it, she said. But she thinks it should have included more information.

Welch, who is opposed to the project, said she thinks more background information on the project would have been helpful, along with links for more online information.

“It just doesn’t seem very scientific to me,” she said.

Mary Graham, senior vice president for the Charleston Metro Chamber of Commerce, which supports the completion of I-526, said she hadn’t heard about the survey. But she assumes the DOT is simply trying to do its own poll.

Her concern, she said, is that the department won’t get a sufficient response from the survey, which must returned by mail.

Graham said the road is vital to the economic development of the area, and her group wants it to move forward. “Now, more than ever, the rest of the road needs to be built,” she said.

Dana Beach, director of the Coastal Conservation League, which is opposed to the project, called the questionnaire crazy and said two aspects of it were particularly troubling.

First, Beach said, the DOT didn’t seek any input in developing it. “Anyone knows that how you ask the question is the most important part of a survey.”

He also said it appeared to be designed to demonstrate favor for completing the road.

There is limited money available in the state for road projects, he said, and projects more important than the completion of I-526. People should have been asked if they prefer to spend the $420 million available for I-526 on that road or other projects.

Beach said he thinks the other state road projects more important than I-526 include $20 billion in necessary maintenance projects, including potholes, bridges and road resurfacing; and economic development projects, such as roads around Boeing, and the widening of parts of Interstates 26, 95 and 85.

Beach said he’s also concerned about how polarizing the controversy around I-526 has become. He’s now more worried that people will be arguing over I-526 a decade from now than he is about how the completion of the interstate will promote urban sprawl.

“Leaders are torquing this process in favor of a project that’s not the most important in the region,” he said. “We need some new leadership.”

Reach Diane Knich at 937-5491 or on Twitter @dianeknich.