In this Sept. 19, 2012 file photo, U.S. Army Corps of Engineers Col. Chris Hall points to a vertical, rock-filled steel tube called a "protector cell" that serves as a buffer that Mississippi River barges rub against, aligning them before they actually enter the lock in Granite City, Ill. Emergency repairs are under way on that structure after workers discovered that an unarmored portion of it exposed by river levels dramatically lowered by the drought split open, spilling much of the rock into the channel and forcing the channel to be closed to shipping. The Mississippi River's 70-year-old system of locks and dams urgently needs upgrades to accommodate barges that have gotten bigger over time, a group of federal lawmakers is warning after last week's dayslong shutdown of the river's busiest lock. (AP Photo/Jim Suhr)
Story Created:
Dec 14, 2012 at 3:45 PM CDT
Story Updated:
Dec 14, 2012 at 3:45 PM CDT