A Carriageway Code is an abbreviation used by some road authorities to describe certain types of roads.
Austroads Carriageway Codes
Austroads uses single letters as carriageway codes, e.g.
A - Undivided two way - no physical barrier or median separating flows
B - Divided carriageway with traffic flowing in prescribed direction
C - Divided carriageway with traffic flowing in counter direction
L - Left car park - carpark on the left hand side associated and parallel to the through carriageway
R - Right car park - carpark on the left hand side associated and parallel to the through carriageway
M - Middle car park - carpark in the centre of divided carriageway
P - Service road in prescribed direction which is accessed from the through carriageway
Q - Service road in counter direction which is accessed from the through carriageway