The Unidirectional Hazard markers (D4-1-1, D4-1-2) are used at road hazards where It is necessary to emphasise to approaching traffic the direction to be taken if the marker appears in the driver's line of approach. The direction is indicated by chevrons, which may point to the left or right as required.
Typical uses of this marker are -
(i) to indicate en abrupt narrowing of the pavement;
(ii) to delineate an exposed median end or other carriageway obstruction where all traffic must pass to one side; or
(iii) to indicate vehicle paths at intersections.

The Unidirectional Hazard marker should not be used:
(A) In lieu of Width markers erected to delineate both sides of the carriageway as specified in Item (0).
(B) In lieu of the Chevron Alignment marker used to delineate sub-standard curves as specified in Clause 3.4.9.

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