A national secondary road () is a category of road in Ireland. These roads form an important part of the national route network but are secondary to the main arterial routes which are classified as national primary roads. National secondary roads are designated with route numbers higher than those used for primary roads, but with the same "N" prefix. Routes N51 and higher are all national secondary roads. National secondary roads have a default speed limit of 100 km/h (62.5 mph) as, along with national primary routes, they fall into the speed limit category of national roads. There are 2657 km of national secondary roads in Ireland, making up slightly over 50% of the entire national route (national primary and national secondary) network. National secondary routes are generally more poorly maintained than primary routes (although their quality can vary widely), but often carry more traffic than regional roads. Almost the entire network of national secondary roads is single carriageway, although there are some short sections of dual carriageway on the Tallaght bypass section of the N81, on the N52 at Dundalk, on the N85 at Ennis, on the N62 at Athlone, on both the N69 and N70 at Tralee and on the N71 between Cork and Bandon. Typically, national secondary roads are of a similar standard or higher than regional roads although some are of lower quality than the better sections of regional roads. Many of them have been resurfaced with higher quality pavements in recent years with relatively smooth surfaces and good road markings and signposting. However, road widths and alignments are often inadequate, with many narrow and winding sections. In the past, most national secondary roads would have run through the centres of the towns on their routes; however, recently, that is less often the case. For example: The N52 bypasses Nenagh (together with the M7), Tullamore, Mullingar, Kells and the centre of Dundalk (as a relief road) The N55 (together with the N3) bypasses Cavan. The N56 forms part of the Donegal bypass and the Mountcharles bypass. The N69 and N70 form part of the Tralee bypass. The N71 bypasses Halfway and Skibbereen. The N74 (together with the M8) bypasses Cashel. The N76 bypasses Callan. The N77 forms the northern part of the Kilkenny ring road. The N80 bypasses Carlow. The N85 bypasses Ennis (together with the M18). The former N8 bypass of Mitchelstown was re-classified as