Regulations made by the Minister for the Environment under sections 45 and 46 of the Road Traffic Act, 1961, in respect of each county specify where special speed limits (which include the 40 mph limit) apply and where exemptions from the built-up area speed limit of 30 mph apply. In the absence of any provision to the contrary in such regulations, a speed limit of 30 mph applies to all roads in each county borough, borough, urban district and town. Local authorities are required to provide appropriate traffic signs to indicate the locations where the speed limits operate.
Regulations relating to speed limits are generally made on a county at large basis and taking account of recommendations made by local authorities, following consultation with the Garda. It is the practice to accept local authority proposals as far as possible subject to the need, in the case of national roads, to ensure reasonable uniformity throughout the network.