Western Australian Consolidated Regulations (1) A driver on a part
of the road that is a service road (except a service road to which a
“two-way” sign applies) shall drive in the same direction as a
vehicle travelling on the carriageway used by the main body of moving vehicles
in the marked lane or line of traffic closest to the service road.
Points: 1 Modified
penalty: 1 PU
(2) In this Part, a
service road to which a “two-way” sign applies is treated as if it
were a separate two-way carriageway.
Two-way sign

Note for diagram There is
another permitted version of the “two-way” sign.