This research investigates factors influencing locking time as well as the source of variation in the locking time on the Upper Mississippi River, and includes tow characteristics and environmental conditions over 1992-2004. The newer 1,200 ft. locks reduce both locking time and time variation, improving efficiency on the system as a whole. Importantly, the analysis suggests lock capacity has declined over the 1992 to 2004 period for all locks. After correcting for tow and environmental characteristics, very little of the remaining variation is explained by a unique vessel identification number assigned by the Army Corps of Engineers, indicating that lockage fees based purely on relative locking times would not provide the intended result.
