US Army Corps of Engineers
St. Paul District Website


Mississippi River Locks and Dams 2–10 Tow Rail System

Published March 14, 2016
Updated: Sept. 19, 2019

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. 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 permanently repair each lock’s tow rail system. Repairing the system may be in conjunction with the lock guidewall crib repair and will be completed during the non-navigation season.


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 begin 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 is expected to begin in December 2019.


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 at the affected locks and dams are completed with 100 percent federal funds.

Fiscal year 2018 costs:

Lock 6 construction contract                          $1,292,000

Fiscal year 2019 estimated costs:

Design-Build for Locks 4, 5, 5A, 7, 8 & 9       $20,237,592