By definition, a power to direct traffic cannot exist unless it is explicitly granted in law.
Under the Road Traffic Acts, the power to direct traffic is given in the first instance to An Garda Síochána. The Acts also provide limited powers to stop traffic in the case of school wardens.
Section 91 of the Road Traffic Act 1961 addresses traffic management in relation to events attracting a large assembly of persons. The section confers certain specific powers on An Garda Síochána in the circumstances in question. Subsection (4) of section 91 also allows an office of An Garda Síochána to authorise a person to act as a temporary parking attendant in such cases. However, this does not include the power to direct traffic.
There is no specific mention of the Civil Defence forces in relation to power to direct traffic in the Acts.