 In addition, a new motorway – the M50 – was built around Dublin.Where a section of national primary road is designated a motorway, signage is white-on-blue instead of white-on-green, in addition, the prefix "N" is dropped, and replaced with "M" instead on road signs.A high quality dual carriageway may be redesignated a motorway by means of an order under the "Roads Act 2007".