Waterway Navigation Structures

hydraulic engineering facilities designed to enable ships to overcome rises in the water level at hydraulic engineering complexes and on canals. The principal types of waterway navigation structures are locks, inclined planes, and ship lifts. Engineering and economic considerations dictate the choice of type. Important factors to be taken into account include ship tonnage, availability of water from the hydraulic engineering complex needed to pass ships through locks, magnitude of the rise in water level, fluctuations in the water level of upper and lower locks, and topographic and geologic characteristics in the vicinity of the hydraulic engineering facility.

The most common waterway navigation structure is the poundlock, which can be designed to pass ships of virtually any displacement over rises as great as 40–60 m at hydraulic engineering complexes located in a wide variety of natural settings. Ship lifts are used primarily for rises of 60–70 m when the flow of available water is limited; they are usually designed to accommodate ships of relatively small displacement (less than 2,000 tons). Combination-type structures consisting of an upper lock and single inclined plane are designed to overcome large rises and large fluctuations in water levels. When the locks at hydraulic engineering complexes with small (3–5 m) heads are flooded, shutter dams with drop gates can provide a practical means of raising the water level by the amount needed to pass ships.

With the expanding use of high-speed vessels, such as hydrofoils and marine air-cushion vehicles, special waterway navigation structures capable of handling high volumes of traffic have been constructed at many hydraulic engineering complexes.