It took 84 years to finish the Trent-Severn waterway that connects Lake Ontario to Lake Huron; it may have made sense in 1833 when it was started but by its completion the railways were dominant, the locks were too small and the trip took too long. The monster infrastructure project never served its commercial purpose and its 44 locks, 39 swing bridges and 160 dams now support little more than pleasure boats. But it is a marvel of Victorian engineering, and perhaps the most remarkable engineering of the whole thing is the Peterborough Lift Lock. It is the highest hydraulic boat lift in the world at 65 feet. (a boat lift in Belgium is higher and bigger but works on a different principle)
But the amazing thing is that it was designed to operate entirely without electricity, just on water power.
Approaching the lift lock from above, before we enter the tank.
Going into the tank from above is a bit scary- it is sort of like an infinity pool where you cannot see the edge. You do see the top of the structure, at the time the largest poured concrete structure in the world.
It gets worse, as the boat noses right up to the edge. Because of Archimedes Principle, adding the boat displaces the equivalent weight in water, so the mechanism doesn't have to deal with any more weight.
Then it drops, entirely powered by gravity. The tank on the rise stops just a few inches below the adjoining water level, designed so that when its gates are opened, enough water will flow in to make it heavier and cause it to descend.
Spectacular engineering, part of a system that enables one to travel 240 miles and climb 840 feet, entirely powered by water. It still runs perfectly 110 years later. That is the way to design a transportation system. A working infrastructure that runs on waterpower ; perhaps it is too soon to call it a commercial failure.
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