Exemption
5. The exemption given by article 4(2) above in relation to regulation 5(1)(b) shall only apply while—
(a) the control device is operable by the palm of the hand exerting a force not exceeding 40 newtons; and
(b) the operator provides, so far as is practicable, in that vehicle or, where an exempted vehicle forms part of a train, in that train a person, other than the driver of that vehicle or train, who is available to assist a disabled person.