Railway crossing signals ahead.  (This sign is used for railway crossings controlled by flashing red lights, in situations where those lights are not clearly visible from a distance of 60 metres for urban roads and 120 metres for rural roads. It therefore warns of the flashing lights and the likelihood that they may be active, rather than of the railway crossing itself. All railway crossings are also signed with W15-5, irrespective of whether they are equipped with flashing lights, automatic barriers, or other safety measures.)
Traffic Control Devices Manual
New Zealand Transport Agency