Work to free a grain barge lodged against a pier of the Interstate 20 bridge over the Mississippi River was set to resume at 7 this morning. Meanwhile, upriver, hundreds of loaded barges were waiting for the obstruction to be cleared so they can continue along southbound shipping channels that have been closed since Wednesday.

A crane-mounted, chisel-like mechanism on barges anchored in the river will cut away at the stuck barge, one of 30 that broke loose from the towboat Kay A. Eckstein in the swift current of the swollen river.

The barge struck the bridge pier and lodged sideways Wednesday, partly obstructing the channel and making shipping hazardous, Coast Guard officials said.

“It backs up millions of dollars worth of products between here and everything north of here,” said Herman Smith, superintendent of the adjacent U.S. 80 bridge that handles rail traffic over the river.

Officials had hoped to start cutting the barge Friday but, after a day spent largely in planning, decided to delay the start until this morning to make sure they had plenty of daylight hours, said engineer Kirk Gallien, assistant district administrator for operations with the Louisiana Department of Transportation and Development, which maintains the I-20 bridge.

“There has been excellent cooperation between the Coast Guard, Louisiana and Mississippi departments of transportation, local law enforcement agencies, the Army Corps of Engineers, and the marine industry,” Coast Guard Cmdr. Scott Anderson, deputy commander of Sector Lower Mississippi River, said in a statement. “Everyone is working together to re-open the river to commerce as safely and quickly as possible.”

Gallien said they hope the chisel, combined with the swift current, will cause the barge to break or fold in half.

“It will at least weaken the structure to where it will wrap around the pier and relieve some of the pressure,” Gallien said. “The other thing it will do is move the part of the barge that is in the channel.”

U.S. Coast Guard officials halted traffic on the river following Wednesday’s accident which also saw several barges hit the old U.S. 80 bridge, which carries trains across the river, and other barges in the tow scatter down river up to a mile south of Vicksburg.

Thursday, the Coast Guard allowed northbound traffic to resume on the Louisiana side — with permission from its Vicksburg Information Center — but said southbound traffic is too risky.

Friday afternoon, a queue of 37 southbound towboats were being held up north of Vicksburg, the Coast Guard said.

Depending on horsepower, said Smith, some could be towing two to three barges, some 30 or more — like those that broke loose from the Kay A. Eckstein.

Barges carrying oil, gas, coal, corn, wheat, soybeans, even quarried rock are being held up at Greenville and other areas upriver.

Many are destined for East Coast cities or international markets, but could also be headed to New Orleans or Baton Rouge, said Smith. They’re bound for grain elevators, oil refineries, storage facilities of all types, and some to ships. It affects commerce “tremendously,” he said.

“Lots of southbound tows are just now getting into the upper Mississippi River from the Ohio, Missouri, Tennessee and other rivers,” Smith said. “There’s all types of products from up north headed to facilities down south. There will be hundreds of barges, hundreds.”

Movement of goods and freight by trains across the old U.S. 80 bridge is expected to be halted for a number of hours today during the chisel operation, Smith said. Trains cannot be rerouted and will have to be stopped at various spots as they approach the bridge.

In 2008, five barge tows struck the U.S. 80 bridge, none in 2009 and one in 2010. With each hit, the bridge has to be closed for safety inspections, sometimes up to six hours. The U.S. 80 bridge last year was also closed twice for repairs, Smith said, once for 12 hours and once for 13.

“They don’t like it,” Smith said of train officials, “but they can live with it and they understand it.”

He could not recall barges hitting and shutting down the I-20 bridge before Wednesday. After the barge hit and stuck, the interstate was shut down for nearly three hours, backing traffic up on both directions for miles.

Big River Shipbuilders and Salvage of Vicksburg has been contracted to get the barge cut and moved out of the shipping channel.

How long it will take is anyone’s guess.

“They could do it in one hit, or they could hit it 1,000 times,” Gallien said. “We just don’t know. It could take 15 minutes or all day.”

Later, when the river level subsides and currents weaken, a salvage operation will be attempted, Gallien said.

“They won’t try to lift it out right now. The river is too high and the current is too strong, and it would be too dangerous.”

While Louisiana transportation officials have no plans to close the interstate bridge, Gallien said sensors and devices placed on the structure would be carefully monitored at all times.

“If we detect stresses,” he said, “we’ll shut it down.”

Forecasts continue to call for the Mississippi River to crest in Vicksburg Tuesday at 43 feet. Friday at 7 p.m. it was at 42.3 feet, up a tenth of a foot since morning.