National primary road

A national primary road (Irish: Bóthar príomha náisiúnta) is a road classification in Ireland. National primary roads form the major routes between the major urban centres. There are 2649 km of national primary roads. This category of road has the prefix "N" followed by one or two digits. Motorways are prefixed "M" followed by one or two digits.

The routes numbered N1–N11 radiate anti-clockwise from Dublin, with those in the range N12–N26 being cross-country roads. Routes numbered N27–N31 are much shorter roads than the majority of the network: they link major pieces of infrastructure (such as ports and airports) to the network, while the N33 is a feeder route to a major motorway (the M1). Finally, the N40 and the M50 are bypass roads of Ireland's two largest cities, Cork and Dublin. National secondary roads (see next section) are numbered under the same scheme with higher numbers (from N51 on). On road signage, destinations served but not on the route in question are listed in brackets, with the connecting route also listed (see thumbnail). Directional road signs on national primary roads are usually in white text on a green background, with the road number in yellow. Signs for roads of different standard are shown using appropriately coloured patches according to a system derived from the UK's Guildford Rules.

Most national primary roads are of at least wide two lane standard, with sections within Greater Dublin and near the regional cities typically being at least dual-carriageway standard. There are however some narrow two-lane sections remaining.

Northern Ireland route sections (which are classified separately according to NI schemes) are in some cases included in a theoretical complete cross-border route – for example the N3 route, which re-enters the Republic. These are listed here in brackets for completeness (and are present on southern road signage).

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