Quote:
Originally Posted by kalos72
I am not sure specifically how these things are built, but I would think that the concrete or a steel plate fronted gate would erode in 150 years.
Not that it would be that hard to repair, assuming steel and concrete were available.
This topic is of great interest to me on the T2K side as well. Rebuilding the river traffic on the Mississippi River.
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The construction is pretty basic once you break it down. You have a channel that is cut and you put a few feet of concrete on the bottom and vertical walls. You then put another concrete floor with openings in it above the existing floor. Each end of this channel created under the bottom is connected to the water above and below the locks with independently operated valves on each. The ends of each lock has steel or iron doors with wood fenders on the inside that are open and closed hydraulically. For the sake of brevity, I left out the construction details of building and removing a cofferdam, the hinge details, etc.
Being in fresh water and with free electricity, anti-corrosion systems should be able to keep the doors intact indefinitely. Wear on the upper and lower hinge is a bigger problem. Last summer I was in Sault Saint Marie and saw the MacArthur lock completely drained during the 20 days it was closed to repair the lower hinge on the upstream side door. This was to replace one of the original anchorage linkages for the doors, which lasted 72 years. These are routinely maintained in the winter when the locks are closed and dewatered for the winter. The wear on these components should decrease, as I doubt that there will still be around 10,000 ships annually traversing the locks.
The oak fenders are routinely inspected and replaced as needed and can be done while the lock is in operation.
The water and residual silt abrading the bottom of the lock is the area I am most curious about. Since the locks are dewatered during the winter, damage from ice formation is minimized.