Those costs associated with a Wal-Mart include adding traffic signals and turning lanes and widening roads.

One geologist who lives off Lake Road, one of the areas that could be impacted by the Wal-Mart, has used his resources and knowledge to create an impact study that indicates the new Wal-Mart could end up costing Jackson County residents upward of $10 million over a period of time.

"This is not alarmist stuff; this will happen," said Steve Gough, who deals with planning and development on a daily basis.

Gough outlined costs for the Supercenter that showed nearly $600,000 to extend Murphysboro's sewer line to the property.

With Wal-Mart comes more business and with the increase in traffic on Illinois 13 will come additional stoplights, which Gough said would cost at least $200,000 each.

"There's no such thing as a Supercenter sitting in a cow pasture by itself," he said. "You're going to have retail sprawl around here."

The Wal-Mart Supercenter in Carbondale did not add a heavy burden to the city, city manager Jeff Doherty said.

The store moved into its current location off Illinois 13 and Giant City Road in 1992 and was originally placed in the enterprise zone. It expanded two more times and two-thirds of the business is part of the zone, which allowed for tax abatements and incentives.

Doherty said when the store came in most of the infrastructure - roadways and traffic signals - was already there.

Greg Smothers, Illinois Department of Transportation District 9 engineer, said a drainage ditch had to be added to the front of the store parking lot to help capture runoff, which he said Wal-Mart paid for.

"We improved that intersection around that time independent of Wal-Mart," Smothers said.

Since that time, he estimated the intersection has had serious improvements three times because of increased traffic flow and growth of business, including Wal-Mart.

Smothers has dealt with many roadway changes because of development and said often a major developer will pay for a traffic signal change. Wal-Mart often pitches in on improvements, he said.

Building an intersection is no small chunk of change, he said. A turning lane costs at least $70,000, and traffic signals at least $130,000.

If the intersection at the corner of Giant City Road and Illinois 13 were to be rebuilt today, Smothers said it would cost $500,000 to $750,000.

Gough said there are other costs associated with a Wal-Mart that cannot be felt by a checkbook. He likes to bike through his neighborhood, but with the roadways expanded and more traffic congestion as people try to drive the back roads to the store, he said he doubts he'll get to do that anymore.

Murphysboro Mayor Ron Williams repeatedly has said the city doesn't have any incentives to offer Wal-Mart. If Wal-Mart won't pay for the extended sewer lines, traffic signals and other initial improvements, he doesn't know that the city will annex the property. However, he said, the city still has not been approached by Wal-Mart.

"I don't know all the answers because we don't know all the questions yet," he said. "I don't see where there's going to be a cost that is great to the city - otherwise I'd be running in the other direction. I don't know that there's anything that could stop them from moving in there."

kristen.cates@thesouthern.com