I still don't understand why anyone building a new canal through Central America would not be trying to maximise the effectiveness of their work by building a sea level canal wide either enough for continuous crossing in both directions or dig two canals and make each one continuous flow in a single direction.

Yes it's a bigger challenge, but these projects are some of the few remaining opportunities in modern economics to say "we expect payback time of two decades" and not get laughed at. No locks no lock maintenance, continuous flow, more ship, more money.

It's also possible to use novel techniques from the last hundred years of progress to "dredge forward" using water itself as an an active tool to wash away all but any hard rock terrain that needs clearing. The rain and loose soils that hurt the first attempt at the Panama Canal could be turned into a positive factor with today's technology.