US Army Corps of Engineers
St. Paul District Website

Mississippi River Locks and Dams 2–10 Tow Rail System

Published March 14, 2016
Updated: April 16, 2020

The tow rail system is integral to the operation of each of the Mississippi River Locks and Dams 2 through 10. It is attached to the top of the lock guidewall and helps guide tows through the lock chamber. Each system is comprised of an operating unit, rail and traveling kevel or “mule.”  The Locks and Dams 2 through 10 tow rail systems have been deteriorating over the past several years, requiring rehabilitation of these systems.


Construction repairs are ongoing at Locks and Dams 6, 8 and 9. Construction will also occur at Locks and Dams 4, 5, 5A, and 7.


The Locks and Dams 2 through 10 tow rail systems have been deteriorating over the past several years. Two failures at Lock 7 identified the need for a project to address serviceability and safety issues. Although interim repairs at Lock 7 were completed in 2014, this project aims to repair each lock’s tow rail system for the next 50 years. Repairing the system will be completed during the non-navigation season from 2019 to 2022 at seven locks and dams.

All sites will have the same design to ensure the navigation industry is capable of operating the tow rail systems in the same way. The rehabilitation also ensures safe working conditions for the navigation industry as well as the lock and dam staff.


The U.S. Army Corps of Engineers’ Inland Navigation Design Center provided guidance and recommended rehabilitating the original design and incorporating a continuous rail. The Corps designed the tow rail rehabilitation at Lock and Dam 6 in fiscal year 2018, and the Corps awarded a construction contract in fall 2018. Construction at Lock and Dam 6 will began in December 2019. The Corps awarded a design-build contract for tow rail at Locks and Dams 4, 5, 5A, 7, 8 and 9 in fiscal year 2019. Construction at Locks and Dams 8 and 9 began in December 2019. Construction will be complete at all three sites in March 2020. Design for Locks and Dams 5 and 5A will begin in early 2020 for the scheduled start of construction in December 2020. Locks and Dams 4 and 7 design will begin in early 2021 and construction is scheduled to begin in December 2021.


Congress authorized the Upper Mississippi River 9-Foot Channel Navigation Project as part of the River and Harbor Act, approved July 3, 1930.


Tow rail design and construction are completed with 100 percent federal funds.

FY 2018 Costs:
Lock 6 Construction Contract                        $1,292,000

FY 2019 Contract Costs:
Design-Build for Locks 4, 5, 5A, 7, 8 & 9     $20,237,592