individual,
Building the whole thing as a bridge does not equate to not building bridges!

Hasbeen, the type of cargo you described would be difficult to handle
by rail and so the cost would be up. Hay might be different and OK.
If oil fuel becomes too expensive the electric semi may become OK.
There have been some work done in that direction. Either Mercedes or
another German company experimented with electric semis and on the
autobahn had overhead wires and pantagraphs on the trucks.
That could give them power for large parts of the trip and charge the
batteries when entering the autobahn.
Tesla has a semi in the works and says they will put it on the market.
I think that oil based fuels will be withdrawn from the market.
It may not happen in the next 20 years but it will happen.