These are examples of inclined planes.
An inclined plane is a system used on some canals for raising boats between different water levels.
Typically, such a feature consists of a slope, up which there are two sets of rail tracks. Boats are raised between different levels by sailing into giant water-filled tanks, or caissons, which have wheels on the bottom and watertight doors at each end, and which are perpendicular to the slope. These are then drawn up or down hill on the rails, usually by means of cables being pulled by a stationary engine. In almost all designs two caissons are used, one going up and one down, to act as counterweights to make the system more efficient. When the caisson has reached the top or bottom of the slope, the doors are opened and the boat leaves.
