It probably needs to be earthquake-proof too, which maybe it doesn't in Baltimore.
So maybe earthquake-proofing is a fair comparison, cost-wise.
Another interesting fact about the Tokyo Gate Bridge (from the Wikipedia article): it's basically made of 3 sections, the two sides and one smaller piece in the middle to connect them. The two side pieces are cantilevers, so they're self-supporting. So if a big container ship managed to strike one side and knock it down, theoretically the other side would remain standing, rather than the whole thing collapsing like the Baltimore bridge.