3 Jul 2025

Inner Harbor Navigation Canal Lock Replacement Study: Hydrodynamic Modeling and Ship Simulation

Abstract: The Inner Harbor Navigation Canal (IHNC) Lock connects the Mississippi River to the Gulf Intracoastal Waterway, surrounded by developed areas in New Orleans, Louisiana. Tow transit times through the current IHNC lock take up to 20 hours. The US Army Corps of Engineers, New Orleans District, has proposed constructing a new lock to reduce tow transit times significantly. However, the new lock will have potential effects on vehicle traffic patterns due to the three bridges across IHNC. To address potential navigation issues, hydrodynamic modeling and ship simulations of the study area were conducted for the three phases of the project: new lock construction, present lock deconstruction, and proposed new lock design. The hydrodynamic model was developed and validated to present conditions, simulating various water levels across the lock structure to provide water levels and currents for ship simulation. The ship simulation was used to record transit times to determine impacts of the waterborne vessel traffic on vehicular traffic due to bridge raising and lowering, as well as navigability of the bypass channels associated with lock construction and existing lock deconstruction. Elicitation from the towing industry was used to inform final design of the new IHNC lock and bypass channels.

6 Sep 2024

Use of Chirp Sub-Bottom Acoustics to Assess Integrity of Water-Control Structures: Inner Harbor Navigation Canal Lock, New Orleans

Abstract: The US Army Corps of Engineers (USACE)-maintained lock on the Inner Harbor Navigation Canal serves as a critical navigation link between Lake Pontchartrain to the north and the Mississippi River to the south. Extensive slumping has been observed on the earthen embankment on each side of the lock, suggesting that internal pathways for water to escape through the lock’s concrete walls or joints are present. Unfortunately, traditional methods often used to identify cracks in the concrete (e.g., sidescan sonar) or water-filled voids under or behind the structure (e.g., ground-penetrating radar) did not identify any structural issues at this site. Prior to dewatering and repair, the USACE New Orleans District requested that the US Army Engineer Research and Development Center conduct a sub-bottom survey at the lock in order to identify water-filled voids and better prepare for potential repairs during dewatering. A unique sled was constructed that allowed a small vessel to tow the sub-bottom profiler at an angle to direct more acoustic energy into the structure. Low frequency, chirp acoustic energy successfully penetrated the concrete walls and identified several water-filled voids on both sides of the lock. A later post-dewatering walk-through indicated that the chirp imaged voids spatially adjacent to cracks, and cracks were not found in any other locations. Additional work is needed to further develop this methodology in other USACE structures.