4.—(1) Steps for use by passengers on a regulated public service vehicle shall (subject to sub-paragraph (6)) comply with the following requirements–
(a)the surface of each tread shall be covered in a slip-resistant material;
(b)step nosings shall be designed to minimise the risk of tripping;
(c)across the front edge of each tread there shall be a band of colour not less than 45mm and not more than 50mm in width, which shall contrast with the remainder of the tread;
(d)the rear of a step shall be closed by a vertical riser between the rear of the tread and either the front edge of the tread above or the floor of the vehicle above;
(e)any step, other than an external step or a step to a seat fitted to any part of a wheelarch or a step in (f), shall–
(i)not be less than 120mm and not more than 200mm in height, and
(ii)the surface of the tread shall not be less than 300mm deep and not less than 400mm wide;
(f)any steps between a gangway and a passenger seat or a row of passenger seats, other than a step to any seat fitted to any part of a wheelarch, shall not be more than 250mm in height; and
(g)in a flight of steps, the difference in height between any two steps shall not be more than 10mm.
(2) The height of a step in sub-paragraph (1) shall be measured vertically from the surface of the tread, and at the centre of the tread width, to an imaginary line extended horizontally from the surface of the next tread or floor of the vehicle.
(3) An external step, leading from not less than one priority entrance and to not less than one priority exit, shall–
(a)not be more than 250mm in height measured–
(i)from the surface of the tread of the external step to the ground,
(ii)if the vehicle is fitted with a kneeling system, with the regulated public service vehicle at its minimum height, and
(iii)at the centre of the tread width; and
(b)not be less than 300mm deep.
(4) A regulated public service vehicle shall not be fitted with a step which can project beyond the side of the vehicle adjacent to the step unless–
(a)the step is protected by parts of the vehicle or otherwise so that it is not liable to injure pedestrians; or
(b)the step can fold or retract so that it does not project beyond the side face of the vehicle and the vehicle is not capable in the normal course of being driven away unless the step is so folded or retracted.
(5) Where a regulated public service vehicle is fitted with a power-operated step, that step shall–
(a)not be capable of operation whilst the vehicle is in motion; and
(b)be fitted with a safety device which stops the motion of the step if the step is subject to a reactive force not exceeding 150N in any direction and if that motion could cause injury to a passenger.
(6) Sub-paragraphs (1)(d), (e) and (g) shall not apply to those steps in a double-deck bus which lead from the lower deck to the upper deck.