Replacement-Lock and Dam No. 26: Lock Capacity Procedure and Scope

A systematic procedure integrating all relevant factors leading to a lock's capacity should be used in determining the practical capacity of any lock on a navigable waterway. These factors should include representative commodity projections, average of maximum tons per lockage, average lockage time, seasonal considerations, and constraints on lock utilization (percent of time lock is in use). By expressing each of these factors on a monthly (i.e., seasonal) basis and then adjusting them over time to account for changes in commodity mix, tow configurations, and technology, it is possible to determine the probable monthly utilization of a lock. Based on queuing models, it was determined that at approximately 90% monthly utilization the practical capacity of a lock is realized. By introducing empirical lock data, many judgmental factors associated with seasonality are eliminated. The process used also shows that lock capacity is not a static condition. Since various factors are constantly in flux, the tonnage capacity varies every month and every year. Because the dynamic nature of the system requires numerous calculations, a computer program written in FORTRAN II was utilized.