10B.—(1) The National Roads Authority may apply, or cause to be applied, by automated means or otherwise, to any national managed road or any part, carriageway or lane thereof, a special limit (referred to in this Act as a "variable speed limit") being a speed limit of—

(a) not less than 20 kilometres per hour, and

(b) not more than the speed limit otherwise provided or having effect under this Act,

as the speed limit for mechanically propelled vehicles on that national managed road, part, carriageway or lane, in lieu of the speed limit provided or having effect under this Act by displaying the speed limit, or causing it to be displayed, electronically on a traffic sign above or to the side of the national managed road, or part, carriageway or lane thereof.

(2) A variable speed limit is in force for the period during which it is displayed in accordance with subsection (1).

(3) The speed limits that may be applied under this section are—

(a) 20 kilometres per hour,

(b) 30 kilometres per hour,

(c) 40 kilometres per hour,

(d) 50 kilometres per hour,

(e) 60 kilometres per hour,

(f) 70 kilometres per hour,

(g) 80 kilometres per hour,

(h) 90 kilometres per hour,

(i) 100 kilometres per hour,

(j) 110 kilometres per hour,

(k) 120 kilometres per hour,

and different variable speed limits may be applied to different carriageways and different lanes on different parts of the same national managed road.

(4) The Chief Executive of the National Roads Authority may authorise persons to carry out the functions referred to in subsection (1).

(5) In any legal proceedings in which it is shown that a speed limit was displayed electronically on a traffic sign above or to the side of a national managed road, or part, carriageway or lane thereof it shall be presumed until the contrary is shown that that the speed limit was displayed in accordance with subsection (1).

(6) A document which has endorsed on it a certificate purporting to be signed by the Chief Executive of the National Roads Authority or a person authorised by the Chief Executive of the National Roads Authority under subsection (4) stating that a variable speed limit applied at a specified location on a specified day, at a specified time or during a specified period, shall, without proof of the signature of the Chief Executive or the person or that he or she was in fact the Chief Executive of the National Roads Authority or so authorised, be evidence, until the contrary is shown, in every court and in all legal proceedings, of the fact that the electronic speed limit applied at that location on that day, at that time or during that period.

(7) Where a speed limit other than a speed limit referred to in subsection (3) is displayed electronically on a traffic sign above or to the side of a national managed road, or part, carriageway or lane thereof such speed limit shall have no effect and the speed limit provided or having effect under this Act shall apply to the road, or part, carriageway or lane thereof.

(8) No action or other proceedings shall lie or be maintainable (except in the case of wilful neglect or default) against any officer of, or person authorised by, the National Roads Authority for the recovery of damages in respect of loss of life and personal injury in respect of any injury to persons, damage to property or other loss alleged to have been caused or contributed to by the performance of functions referred to in subsection (1).]