After working my way through several provinces and districts of Cambodia, I’ve revised my Transportation Index as follows:

-4 No significant road connections -3 Roads that connect to the district’s edges/town center but few roads permeating -2 One road all the way through the district One or more roads all the way through but no crossings -1 Multiple roads that converge/cross. 0 Multiple crossings and/or a fairly good transportation network permeating the district +1 National highway connection / crossing +2 Domestic airport, railroad, or other mass transit point +3 Regional airport (e.g. connections to neighboring countries) +4 International connections (outside neighboring countries, e.g. to other continents?) +5 Major International Hub (a la London, Singapore, Bangkok, New York, etc…)