The Port Authority is a building that you can only build on coasts. This building enables the transfer of goods between your city's stockpile of goods and ships much like a warehouse. The Port Authority cannot be upgraded, but it has a flying carrier, as well as being able to dispatch additional transports via roads. Note that it only has 1 transport unit if you don't have any Ark upgrades which increases the number of transport units. The most units in one upgrade is 2 extra ones. This is useful when it is busy around the Authority.