Questioning of persons on board or alighting from trains

9.  Where there are reasonable grounds for suspecting that there is a significant danger to public health because a person either is believed to be a sick traveller or may have been exposed to infection with a serious epidemic, endemic or infectious disease, an enforcement authority may require him while he is on or when he alights from an international train—

(a) to answer in a control area questions pertaining to his current state of health or his contact with the possible source of infection;

(b) to answer in writing in a control area questions about his name, address and intended destination.