J_T,
As you are aware we operate a very diverse VIP fleet, some of our requested destinations are quite interesting. Presently we use 45m as a minimum, but the latest request was for a MD90 to operate to a 20m wide runway, we were informed that the local oil company happily operate B737's into this 1700 m field.
Do you have any reference to the criteria used by ICAO/CASA for determining the minimum width required?
Mutt