What does merge in turn mean under the Northern Ireland Highway Code?

Merge in turn means vehicles from two lanes take turns to join the continuing lane, typically where slow-moving traffic is narrowing into one lane.

It is not a licence to race to the front at speed; the method is intended to reduce queue length and make best use of available carriageway.

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 does merge in turn mean under the Northern Ireland Highway Code?” — the practical point is: At the merge point, cooperate, leave a usable gap and follow any temporary roadworks signs controlling which lane continues. 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.