The Greenup Locks and Dam, located on the Ohio River at Greenup, Kentucky, is one of the busiest locks in the Huntington District of the U.S. Army Corps of Engineers.But maintenance work closed the main lock chamber since April 15, 2016, while crews removed -- and replaced - the massive miter gates at the downriver end of the lock.That can affect industry, causing barge traffic to slow down on the Ohio River -- and it brought a visit from Congressional representatives from three states -- Bill Johnson from Ohio's 6th District and Evan Jenkins from West Virginia's Third District as well as staff members from Senator Mitch McConnell's and Congressman Hal Rogers' of Kentucky offices.The group had the opportunity to see the lock's main chamber dewatered and view the recently replaced main chamber miter gates. Also, they were given a tour of the facilities by Corps officials, including District Commander Col. Philip Secrist. This included an up-close look as workers neared completion of the installation of the new miter gates.Those gates make it possible to lock through river traffic moving up and down the Ohio River. The traffic -- usually a tow pushing barges loaded with coal or other materials -- move carefully into the lock chamber. The gates are closed and the water level is either raised or lowered, depending on whether the boat is moving up or down the river. Once the water level is right, the other gates are opened and the tow moves on.Each gate weighs 250 tons, and the just-replaced gates have been in operation since construction of the lock was completed in 1962.While the main chamber was closed, traffic continued to lock through at Greenup using the smaller auxiliary chamber. At 600 feet long and 110 ft. wide, the auxiliary chamber is half the length of the main chamber. That means most tows locking through must split in half -- locking some barges through in one lockage, and the rest in a second lockage. It meant that traffic slowed down until the main chamber was back in operation.The replacement of the lower miter gates was completed on Aug. 25 and the main lock was put back into operation. The joint efforts of the Huntington and Louisville Repair Fleets resulted in completion almost 5 weeks ahead of schedule with overall savings of nearly $1 million.The Greenup Locks and Dam was built in 1962, and is a vital component of the Ohio River Navigation System. In 2014, 245.9M tons of commodities moved through the Ohio River Navigation System at a value of $46.3B. At Greenup Locks and Dam alone, 39.6M tons of commodities passed through at a value of $11.7B. The recent chamber miter gate replacement initiative of the Greenup Locks and Dam will ensure this vital piece of infrastructure continues to perform its mission for many more decades to come.