Lock extensions for navigation improvements in the United States inland waterways

The United States waterway system finds itself facing increasing commercial traffic while the system's infrastructure has essentially reached its design life. The result is an increased demand on the nation's navigation locks. Financial constraints require innovative design concepts on infrastructure improvements. The overall savings estimated from the use of these innovative construction concepts for the US Army Corps of Engineer's top 11 high-priority navigation projects (lock replacements) are between 1.4 and 1.8 billion dollars. One of the innovative designs being considered by several projects is extending the lock walls of existing 204.2 m locks and converting them into 408.4 m long locks. A cost effective design alternative being considered for the filling and emptying system is the use of existing 204.2 m lock systems to fill the 408.4 m locks. This type of system is hydraulically unbalanced and could be prone to extremely slow filling and emptying times, and higher hawser forces. If the filling and emptying times are slow enough to adversely affect the total transit time, significant economic losses could occur. Also, if the hydraulic performance of the system is poor, the risk of accidents increases due to excessive hawser forces and surface disturbances. Research on these systems has determined minimum filling and emptying times, with acceptable hawser forces, minimal surface drift, and disturbance. Design guidance is developed from a combination of laboratory flume data supplemented with computational modeling results. This paper presents the modeling methods used to establish design criteria. This criterion is necessary for design engineers investigating the 204.2 m extension alternative.