McAlpine Locks and Dam are on the Ohio River at the northwestern end of Louisville, KY, 606.8 miles below Pittsburgh, PA. The structures, including the dam, the canal, and locks, extend from mile 604.4 to mile 607.4. The upper pool of the dam extends approximately 75 miles upstream to Markland Locks and Dam near Warsaw, KY. The provisional plan recommended in the McAlpine Navigation Feasibility Report consists of constructing an additional 110 by 1,200 ft. lock in place of the existing auxiliary chamber. This would result in two locks 110 ft. wide by 1,200 ft. long. The new lock would be parallel to the existing 1,200 ft. lock, with the upper gates in approximately the same location as the existing lock upper gate. A guide wall would extend upstream 1,275 ft. beyond the upper miter gate monolith and tie into the existing canal wall. A south guide wall would extend 1,200 ft beyond the lower miter gate monolith. A fixed bed model reproduced the Louisville and Portland Canal, the existing locks, a limited section of the Ohio River immediately upstream of the canal, that part of the river channel between Shippingport Island and the fixed crest weir connecting the upper and lower spillways, and the lower approach to the locks at an undistorted scale of 1:80. Upstream of the lower spillway, the right descending model limits followed the alignment of the fixed crest weir from the upper gated spillway to the lower gated spillway. However, as the model would not be reproducing any river flows that would create flow over the fixed crest weir, the crest elevation of the weir was not reproduced in the model. The general design of the new 1,200 ft. long lock was complicated by its proximity to the existing 1,200 ft. lock, its placement at the downstream end of a long approach canal, and the restricted area downstream of the lock available for lock discharge laterals.