To overcome this, the U.S. Army Corps of Engineers dredged an 8.5-mile-long cut-off canal between Chouteau Island and the Illinois shore, parallel to the river, and constructed a lock in the channel, bypassing the obstacle.

The structure includes two locks, both 110 ft wide, one 600 ft long and the other 1,200 ft long. The walls are up to 92 ft high and 45 ft wide.

The miter gate leaves of the main lock are 72 ft high, 61 ft wide, 5 ft thick, and weigh 170 tons. Double leaf gates guard against large ice flows.

The canal required 25 mil cu yd of dredging. Dredging of the lock was primarily done by cutterhead dredges, followed by clamshell and cableway down to bedrock, with the final 10-ft excavation into bedrock achieved by drilling and blasting.

Conveyor belts supported by steel towers and trestlework moved four grades of aggregates and concrete mixtures.

Looking for quick answers on construction and engineering topics?
Try Ask ENR, our new smart AI search tool. Ask ENR →

The project’s workforce peaked at 1,000. Dredging began in 1947 and the lock entered operation in 1953.

Lock 27 is the southernmost lock on the Mississippi River and moves the most cargo of any lock on the river.