Road traffic signs in Ireland fall into three main categories
These signs are usually circular and set either upper or lower limits, prohibitions, and directions, all of which must be adhered to. The context of the sign is legally enforceable, for example, circular signs with a red border, white background, and black numbers in the range 30, 40, 50, 60, 80, 100, 120, set the maximum speed limit at which it is permissible to drive on that section of road. A circular sign with a red border, white background, black arrow pointing up, and a red diagonal bar across it prohibits vehicles from entering and going straight ahead. A blue circular sign with a white (pointing in any direction) is a direction that you must follow.
These signs are usually diamond shaped and warn drivers of a variety of hazards ahead such as, dangerous bends, junctions, railway crossings, and cross winds. They are usually either, yellow for permanent hazards, or orange denoting temporary roadworks. A typical example of a warning sign of a permanent hazard would be a yellow diamond with a black graphic of car going off a quayside into water which is a warning there is an unprotected edge of a quay. One warning sign which is noteworthy is the orange diamond with the graphic of a man working, which is warning of a roadworks ahead. This sign is noteworthy because it has legal backing in that once a driver has passed that sign they are legally obliged to drive with caution through the roadworks.
These signs are usually square or rectangular shaped and provide drivers with information and come in a variety of colours. Signs with a brown backing contain information on places of local interest, scenic areas, historical monuments, and service areas. Signs with a white background generally provide information on routes, locations, directions. Signs with an orange background are associated with roadworks and are commonly found providing information on temporary detours and diversion routes.
It is possible to combine two or more signs together on grey composite boards such as, the warning sign for children playing, the regulatory sign for 30 km/h speed limit and an information supplementary plate stating, ‘Slow Zone’. Composite boards with various combinations of signs are also often found on approaches to villages and towns on National and Regional routes.