"It's only in the event of extreme need," Sanford said in a news conference on Hilton Head, one of three stops the governor made along the state's coast Tuesday to announce additional lane reversals. "If the folks down this way evacuate on time, the four lanes will never be used."

The governor's plan also calls for additional lane reversals in Horry County and tweaks plans for reversing the eastbound lanes of Interstate 26 between Charleston and Columbia -- most notably that motorists will be able to leave the interstate from the reversed lanes at most exits.

Sanford cited the massive traffic tieups during the 1999 evacuation for Hurricane Floyd. He said it took his wife, Jenny, and their children about six hours to drive from Charleston to Columbia during the evacuation before the storm.

The four lanes of westbound traffic on U.S. 278 would start near the highway's intersection with Spanish Wells Road and would continue to the U.S. 278 intersection with S.C. 170.

Sanford said he would call for all four lanes to travel westbound if an approaching hurricane significantly increases in strength or speeds up, or if too few people evacuate the area early.

The regular evacuation plan calls for three lanes of westbound traffic on most of U.S. 278.

The eastbound lanes on U.S. 21 between S.C. 280 near Beaufort and Gardens Corner also could be reversed.

"It does in fact reduce clearance time -- at least on paper," said Jon Boettcher, state hurricane program manager. "None of these models has been put in effect. Indications are it could save hours."

But reversing all four lanes of U.S. 278 and U.S. 21 also means no one can travel toward Hilton Head or Beaufort on those roads -- an issue that concerns Beaufort County Sheriff P.J. Tanner.

"I commend the governor for being innovative, but those plans have problems," Tanner said Tuesday evening from a conference in Columbia.

In particular, Tanner said, if all four lanes were traveling west on U.S. 278, then emergency vehicles will have troubling responding to emergency situations on the island.

"There's going to be congestion, and moving of services will be difficult," he said. "Not everybody evacuates during a hurricane. Some stay behind, including some of the criminal element, who stay behind for looting."

Sanford said once westbound motorists are traveling in all four lanes, traffic would have to be stopped to allow emergency vehicles to head east toward Hilton Head.

But Tanner also said he fears the governor's plan actually may encourage people to delay evacuating because they think they will have no problem getting inland.

"We don't want to encourage people to wait to the last minute," he said.

Beaufort County Council Chairman Weston Newton said in an interview Tuesday evening that people involved in coordinating an evacuation in Beaufort County, such as William Winn, the director of county's Emergency Management Department, and Tanner, had commented on the governor's plan to use all four lanes, but Newton said he hadn't seen the final plan until it was announced Tuesday.

He said the county and municipalities would now begin working on how to deal with reversing all four lanes on the two highways in the county.

Tanner said he still hasn't seen the final plan. In fact, no local fire department or local law enforcement representatives were at Tuesday's news conference.

"I would like to see better communication (from the governor) with local law enforcement," Tanner said.

But the bottom line for the success of any evacuation plan, Tanner said, was how traffic moved in the inland counties.

"The coastal counties and sea islands can move only as fast as the inland counties allow," he said. "That was the problem with (Hurricane) Floyd in 1999 -- the inland counties were congested. Hopefully, the problems of 1999 have been addressed."

Lt. Col. Harry Stubblefield of the state Highway Patrol said people shouldn't expect to get to their destination as quickly as during a normal commute, but he expected traffic in the emergency four-lane evacuation to move at about 35 mph.

"You're going to be slow," Stubblefield said at the news conference. "Our focus is to keep you moving (and) get you there in a reasonable amount of time."

"This continues to be a work in progress," Sanford said. "We think we really need to have expedited routes."

The hurricane season runs from June 1 to Nov. 30.