LeTourneau Road, under the swollen Mississippi River from Glass Road to LeTourneau Technologies, will remain closed to most traffic — even after the water recedes — until tests can be completed, the Warren County Board of Supervisors decided Monday.

Engineers must wait for enough dry space atop the road, or “freeboard,” so an outside geotechnical firm can drill holes in select spots to check for subsurface water, said Brian Robbins of ABMB Engineers, the county’s engineering firm. Still, visual inspections could begin this week, he said.

The section of roadway under water was closed to vehicles May 6. The Mississippi River at Vicksburg was 48.9 feet this morning, down about a half-foot since Monday. Its crest at 57.1 feet May 19, or 14.1 feet above flood stage, was the highest in Vicksburg since 1927. The river will remain above the 43-foot flood stage until the middle of next week, according to the Army Corps of Engineers.

The board specified no weight limit, but did acknowledge any traffic restriction would only work with the help of the sheriff’s department. District 4 Supervisor Bill Lauderdale, who met with LeTourneau Technologies, Martin Marietta Aggregates and Lynn Welding Shop last week, defined “light traffic” as any vehicle lighter than a 12-passenger van. Damage to the public boat launch next to the riverside oil rig fabrication yard will also be a curiosity for onlookers.

“Everybody’s going to want to see the landing,” Road Manager Richard Winans said before the board OK’d a physical sign to post on the road once water recedes. “So, there’s more than just businesses affected there.”

At LTI, a reduced work crew has been boated to the yard since early May. On May 16, parent company Rowan Companies announced it will sell the Vicksburg and Longview, Texas, plants to Milwaukee-based mining equipment maker Joy Global Inc. for $1.1 billion. Officials have said the 600 jobs at the south Warren County plant will be retained.

If the deal clears routine regulatory hurdles, the plant is expected to make more mining machinery than shallow-water jackup rigs. Work on the $150 Joe Douglas rig should resume and staff should go “into full cleanup mode“ once river stages at Vicksburg dip to 45 feet, plant manager Bo-D Massey said.

“We’re still in maintenance mode right now,” Massey said.

In 2008, the plant closed for nearly two months and a mile-long section of the eastbound lane washed out, prompting a $216,000 reconstruction of the lane and shoulder. Raising the road above current elevations was then estimated at $2.1 million.

Power is still out for 260 Entergy Mississippi customers countywide, spokesman Don Arnold said. The figure includes homes on Glass Road and areas inside the city along North Washington Street.