Hierarchical delivery system

Question

Can you believe of another familiar system which routes employing a hierarchical delivery system?

Answer 1

At airport system. At the core routing level, there are main hub airports like Denver, New York, Chicago, and Atlanta. The core airports are accountable for routing people and cargo to main geographical regions. Core airports join with regional airports which serve a specific region; regional airports are at the distribution layer. Lastly, to reach your final destination, you can take a cab, a bus, a train, or rent a car. This can be considered as the access layer.