There are protocols defined by engineers to control and manage the flow of digital signals. Then these packages are sent to the next stop site in a local network. This process will continue until the destination site receives the packages then the destination site will reconstruct the whole data and send a received signal to the original site to tell it to stop the sending of these packages. In fact, the real protocol of network is more complex and sophisticated than what I described here. The time of transportation mainly depends on the number of intermediate sites and the capacity of the network.
Some networks charge maintenance fee for the use of their networks.
The use of route is almost free for users now. But in the future, some superhighways might establish a toll station in them because the use of network will be more commercial. Then we should reconsider which route will be the most economic path. Some compression technique can minimize the size of data and improve the efficiency of transportation. The technique of data compression also plays a very important role in data transportation.