Sometimes, aqueduct engineers should carve a tunnel through a mountain rather than build a trench around one ... the valley in watertight pipes. Water pressure forces water up the other side.

an open trench, a deep tunnel, an aerial structure and an at-grade rail system. The estimates do not include the costs of purchasing the needed right-of-way, which is owned by the Peninsula ...

Then one by one, preassembled, watertight tubes are floated out and lowered into place over the trench. Divers bolt each segment together to form the complete tunnel. The tunnel is then covered ...