Hi Ali,
I agree with your rule of thumb.
* Controlled-Access == Freeways (US) == Motorways (UK) == Expressways, usually closed tolled, U6/R6 (MY)
* Limited-Access == Expressways (US) == Motorways (UK) == Expressways, usually open tolled, U6/R6 (MY)
* Primary-Highway == National-Highway (US) == Primary routes/Trunk Roads (UK) == Federal Route/Highway, U5/R5 (MY)
The access control criteria (full control vs partial/limited control) is the more universal criteria, though not the names the roads usually known as. AFAIK, both UK/MY does not differentiate Freeways/Expressways in common usage.
I note MapMaker's current order of road priorities clearly shows Freeways/Expressways is higher quality than Highways, versus the old order of road priorities.
Current Old
1 No Auto Traffic 8 Non
Traffic
2 Private Road 9 Terminal
3 Local Road 7 Local
4 Minor
Artery 6 Minor Arterial
5 Major Artery 5 Major Arterial
6
Regional Highway 2 Secondary Road
7 National Highway 1 Primary
Highway
8 Expressway 4 Limited
Access Roads (corrected)
9 Freeway 3 Controlled Access Roads (corrected)
Ref:
http://www.fhwa.dot.gov/planning/fcsec2_1.htmhttp://wiki.openstreetmap.org/wiki/Highway_Functional_Classification_System
http://en.wikipedia.org/wiki/British_Road_Numbering_Schemehttp://keselamatanjalan.jkr.gov.my/roadsafety/editor/files/File/Arahan%20Teknik%20Jalan/ATJ%208_86%20A%20Guide%20On%20Geometric%20Design%20Of%20Road.pdf (page 16)
http://sites.google.com/site/mapyourworldcommunity/map-your-world/discuss?place=msg%2Fgoogle-mapmaker%2FKp14x_G58SM%2FjZBaB_LSuVcJ (my earlier post)
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regards,
sabre23t =^.^=