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A lock on the future of shipping

Today’s MI Environment story by Mollie Mahoney, of the U.S. Army Corps of Engineers, is from the State of the Great Lakes report.

Construction continues on a new ship passage at the Soo Locks. Photo courtesy of U.S. Army Corps of Engineers Detroit District.

Construction continues on a new ship passage at the Soo Locks. Photo courtesy of U.S. Army Corps of Engineers Detroit District.


Imagine if three-quarters of United States integrated steel production stopped. Imagine nearly all North American production of appliances, automobiles, construction equipment, farm equipment, mining equipment, and railcars ground to a halt.

That’s the scenario laid out in a 2015 Department of Homeland Security study that envisions a two- to six-week unanticipated closure of the largest of the Soo Locks with no alternative connecting Lake Superior with the lower Great Lakes and ultimately the rest of the world.

A six-month unscheduled closure would be even more impactful, with 11 million lost jobs and a $1.1 trillion hit to the U.S. gross domestic product. A new Soo Lock, in its fourth year of construction, will avert that dire scenario.

Currently, two of the Soo’s four locks are open for use: the 1,200-foot Poe Lock and the 800-foot MacArthur Lock. Because the smaller lock can’t accommodate many of the lakes’ iron ore freighters, around 88% of iron ore passage relies on the Poe Lock.

The unnamed lock will replace the decommissioned World War I-era Sabin and Davis locks. After the commissioning of the new lock, the Poe Lock will be taken out of service for several years for major rehabilitation. Once rehabilitated, the new lock and the Poe Lock will be used interchangeably, giving the Soo two 1,200-foot locks.

With a total investment estimated around $3 billion, the new lock is being built in three phases. The first, deepening the upstream approach channel, was completed in August 2022.

Phase 2 work includes rehabilitating the upstream approach walls to guide vessels into the new lock and will allow the vessels to moor on the wall. The phase was 80% complete in its third year of construction in fall 2023 and is estimated for completion in summer 2024. Phase 3 includes demolishing the decommissioned Sabin Lock; building the new lock chamber walls, floor, and gates; and installing mechanical and electrical systems – including an innovative hands-free mooring system.

The base contract for Phase 3 was awarded in 2022 and is slated for completion in 2030. The contract was 9% complete as of late summer 2023, with ongoing construction on several activities. In 2023, the focus included abating of hazardous materials, demolishing existing structures, building a new bridge to the hydropower plant, and excavating for a new utility shaft all in preparation for dewatering the construction site in 2024.

The new lock was designed to mirror the Poe Lock but will include some new features, such as the hands-free mooring units. These units are essentially vacuum pads that hold the ship in place, moving up as the chamber fills or down as it empties. The system is a safety upgrade to using line handlers, the current method of mooring ships in the lock chamber.

About 80 million tons of commercial commodities a year, including about 95% of all the iron ore mined in the U.S., pass through the Soo Locks. The facility is operated and maintained as the largest project of the U.S. Army Corps of Engineers’ Detroit District.

Based on the corps’ latest regional economic modeling estimate, the new lock will support more than 1,200 jobs a year at peak construction and use many American-made and -mined products.

Senior Project Manager Mollie Mahoney manages the ins and outs of the New Lock project to include project planning, team integration, stakeholder engagement, timelines, goals, and budget. She says she enjoys going out to the New Lock project site and seeing the changes from month to month.