The use of any mechanically propelled vehicle on a public road is subject to regulations, principally the Road Traffic (Construction, Equipment and Use of Vehicles) Regulations, 1963 to 2002 which, inter alia, prescribe the maximum permissible laden weights of vehicles. In the case of any individual vehicle the maximum permissible weight will be determined by a range of vehicle characteristics including number of axles, type of suspension and the vehicle's design weight. All vehicles using public roads are required to comply with the provisions of these regulations unless they are covered by a special permit under article 17 of the 1963 regulations.
Article 17 makes provision for the issue of special permits by local authorities for the limited use of vehicles which do not comply with the regulations, including the weight requirements, on an exceptional basis. In issuing permits local authorities may insert any limitations, restrictions or conditions, including conditions as to weight which they consider advisable to prevent unnecessary damage to public roads or which, after consultation with the Commissioner of the Garda, they consider expedient to protect other road users.