The infrastructure cost of a post-Panamax St. Lawrence Seaway

What would expanding the St. Lawrence Seaway to post-Panamax capacity do to the surrounding landscape and economy?

The economic effect could be large, but widening and deepening the route would require costly reconstruction of bridges, channels, and their supporting concrete works.

Expanding the St. Lawrence Seaway for post-Panamax ships would require corridor-wide reconstruction. The larger vessels need far more width, depth, water, and structural support than the present route provides. Bridges and other infrastructure would have to be rebuilt or reorganised around the new navigation envelope. The discussion anticipates a large economic impact and a very high capital cost.