While the Road Traffic Act 2004 sets default speed limits for various categories of roads, elected members of local authorities have statutory responsibility for deciding on and making appropriate Special Speed Limit bye-laws for roads within their administrative area and, in the case of national roads, subject to the consent of Transport Infrastructure Ireland (TII). The making of such bye-laws is a reserved function of the elected members of the council.
To assist local authorities in the application of Special Speed Limits, my Department's updated Guidelines for Setting and Managing Speed Limits in Ireland, which is available on my Department’s website, reiterate the statutory responsibilities of elected members in relation to the making of such Special Speed Limit bye-laws, while providing Guidelines which take account of relevant national policy and local circumstances - including road safety. These guidelines also draw on Irish and international research.
In general much research has been carried out into speeding and its effects. This also includes research carried out in Ireland and in partnership with international organisations and includes work carried out by the Road Safety Authority (RSA).
Noting this, I am referring your question to the RSA for further comment on the matter.