A railroad bridge crossing the swollen Mississippi River in southeastern Iowa remained closed Friday, a day after it was struck by a grain-filled barge.

The BNSF bridge at Burlington is part of a main rail for freight and passenger traffic and its closure has disrupted schedules for more than 100 trains, BNSF Railway spokesman Steve Forsberg said.

“We can’t reroute that many trains,” he said.

Forsberg said crews tried to sink the barge that was pinned against the bridge, but it only sank to a certain level before stopping. He said crews would begin vacuuming out the grain from inside the barge so they can tow it away and inspect the piers for damage.

“If things go well, we’ll begin running trains on the rail at restricted speeds later today,” Forsberg said Friday morning.

The bridge was closed early Thursday morning after several barges broke away from a staging area upstream. Three of the barges struck a pier on the U.S. Highway 34 bridge that connects Burlington and Gulfport, Ill., and one of those also hit the railroad bridge.

The highway bridge, also called the Great River Bridge, was closed for more than 12 hours before reopening by mid-afternoon on Thursday.

Amtrak’s California Zephyr, which runs from Chicago to San Francisco, travels through Iowa. Eastbound passengers were taken by charter bus from Iowa to their destinations Thursday, while other trains have been rerouted, Amtrak spokesman Marc Magliari said.

“It’s a very, very long detour,” he said.

The Coast Guard was investigating how the barges broke free, but Lt. Cmdr. Tim Whalen said it appeared the level of the river _ more than five feet above flood stage _ and the swift current and debris in the water were contributing factors.