What does it mean if something is transported using "intermodal transportation"?

Intermodal transportation means that there are multiple modes of transportation say by train, ship and a tractor/trailer without anyone touching the items inside the container.

If you live close to a seaport, you will see trains carrying railcars that get loaded onto 18-wheelers who take them to the seaport to load onto the ships.

Hope that helps!

congress also has implied powers, which derive from the necessary and proper clause of the constitution and permit congress "to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states.