Practical Tonnage Capacity of Canalized Waterways

This paper develops the relationship between the practical tonnage capacity of a waterway and its maximum tonnage capacity. The relationship is found to be an approximate ratio of 1 to 4, that is, the PTC of a waterway is approximately 25% of its MTC. The maximum tonnage capacity is computable for all waterways. This tonnage is described as the optimum amount that can pass a lock in 365 days if each time the lock is operated, regardless of direction. Its useable chamber dimensions are completely occupied by a tow with its barges loaded to the maximum draft permitted by the waterway, each lockage is performed in the minimum possible time, and the operation continues for 24 hr each day. Waterways with restrictions such as narrow channels requiring passing places were found to have relatively lower practical tonnage capacity than the waterways developed on the Illinois and Ohio Rivers. The findings are suitable for application to studies of new waterways or the improvement of existing ones.