The physical network stack

5th September, 2006 with a response from kyb

For a while I've been trying to work out what the difference is between the road and rail network. Specifically, I'd like to know why the rail network was fantastically successful in the 19th and early 20th centuries, but has been comprehensively beaten by the road network in the later 20th century.

In order to make comparisons easy I have decided to split physical networks (as opposed to data) into a stack:

  1. Pathway layer
  2. Link layer
  3. Vehicle layer
  4. Object layer

By way of example I have created this table of a few choice networks:

RoyalMail™ Rail Road
Pathway Any of the other physical networks Track Motorways (freeways), roads, tracks, fields (depending on vehicle), the rail network, ferries
Link Sorting office, postbox Stations, terminals Gates, road junctions, garages
Vehicle Envelope, parcel Rolling stock Cars (and taxis), lorries (trucks), buses (including coaches), tanks, tractors, combine harvesters, motorcycles, bicycles
Object Any inanimate object up to 20Kg Pretty much anything Pretty much anything

From this a few interesting questions arise. For each network:

  1. who controls each of the layers,
  2. by how much,
  3. and how does that control affect other users?

I'll admit that I haven't thought about those yet, but hopefully this exercise has brought me closer to answering my original question. I'm just not quite sure how.

A response from kyb

15th September, 2006

I like the analysis. It's interesting to use the tools we learn from computer science to think about real world things. I expect that the answer to the original question though is very straight forward, and to do with the economics of freedom and convenience.