Replacement-Lock and Dam No. 26: Projecting Waterborne Commerce-Inland Navigation

The determination of a lock's capacity necessitates projecting commodity tonnages expected to pass through that lock in the future. For long-range projections of waterborne commerce passing through a limited reach of the river, a market-oriented commodity group analysis is best. Given different objectives, a more appropriate procedure may be correlation analysis or an analysis based upon trend data. Whereas aggregate correlation analysis has many advantages for a large universe, for a small reach it has many shortcomings. Likewise, trend analysis may be appropriate for short-run estimates, but can be misleading for most projects over 5 yrs. Most important, however, is that for a limited reach, causation should be established. This can best be accomplished through a clear definition of the commodity group, the careful identification of areas of supply and demand, and the quantification of this demand (over a period of time) as it pertains to barge transportation.