What do triangular warning signs mean in Northern Ireland?

Triangular signs in Northern Ireland are warning signs used to alert drivers to hazards ahead.

The red-bordered triangle warns rather than orders. The symbol inside identifies the hazard, such as bends, junctions, animals or changing road conditions.

Northern Ireland's Highway Code uses signs, signals and road markings together, so the safest reading is always the exact sign at the location plus any lane arrows, plates or temporary traffic management. Rules expressed as ‘must’ or ‘must not’ are legal requirements; advisory wording can still be used as evidence when responsibility for a collision is considered.

For this exact question — “What do triangular warning signs mean in Northern Ireland?” — the practical point is: Reduce speed early enough to react to the hazard and look for supplementary plates giving distance or extra detail. The answer should be applied to the actual signs, conditions, licence wording or parking rules in force at the time, because temporary restrictions and individual DVA decisions can change the ordinary position.