Control Alternatives at a Waterway Lock

Three types of control alternatives are evaluated in this paper: tow dispatching control, speed control, and combined control. Lock control covers several heuristic methods for sequencing tows through waterway locks, including locks with two dissimilar chambers. Two lock control algorithms are compared with the usually used first come first served policy. Of these, the shortest processing time first (SPF) gives priority to tows with lower processing time per barge, and chamber packing without tow breaking (PAC) combines integral unbroken tows into chambers up to chamber capacity. The resulting improvements in delays and capacity are evaluated by comparing these algorithms with the first come first served operation. Here, barge delay savings of up to 77.78% with SPF and up to 87.98% with PAC are shown in the results at a congested lock. Cost savings of up to 66.37% with SPF and up to 76.61% with PAC are projected at a congested lock. Real-time speed control explores the possible fuel cost savings of slowing down tows before they reach a queue at a waterway lock. It mainly substitutes slower motion to faster motion followed by idling. However, in the case studies presented here, speed control reduces average cost by values ranging from 6.288 $/barge (0.6%) to 76.804 $/barge (4.48%) depending on congestion levels. The fuel cost savings range from 54.377 $/tow (2.02%) to 1,042.989 $/tow (36.9%). Here, the combined lock and speed control algorithm further improves the average cost by values ranging from 5.54 $/barge (0.6%) to 502.41 $/barge (29.34%).