In general, tactile indicators require to be 600mm to 800mm deep; commencing 300mm +/- 10mm from the edge of a stair or ramp (Refer diagram 1).

When there is an obstruction within 3000mm of a stair or ramp, tactiles must be reduced  to 300mm to 400mm deep; to adequately warn users of an impending hazard (Refer diagram 2).


Diagram 1
Tactile Diagram
Diagram 2