DfI Roads (formerly Transport NI and, before that, the Roads Service of Northern Ireland) is the sole Road Authority in Northern Ireland, responsible for all public roads, as well as footways, bridges, and street lights. It is part of the Department for Infrastructure (DfI), which was previously known as the Department for Regional Development (DRD).
In the remainder of the UK, trunk roads are the responsibility of national entities, such as Highways England, whilst other roads are looked after by local authorities. In Northern Ireland, however, all public roads are the responsibility of the Department for Infrastructure.
Clarence Court 10 - 18 Adelaide Street Belfast BT2 8GB
Classified unnumbered (Class III) roads
For its Class III road network, Northern Ireland uses "C" prefixes.