3.—(1) Subject to the following provisions of this paragraph, the powers under article 7 of this Order to break up or open a street shall not be exercisable where the street, not being a highway maintainable at public expense (within the meaning of the 1980 Act) is under the control or management of, or is maintainable by, a navigation authority, except with the consent of that authority.
(2) Sub-paragraph (1) shall not apply to the carrying out under this Order of emergency works, within the meaning of Part 3 of the 1991 Act.
(3) A consent given for the purposes of sub-paragraph (1) may be made subject to such reasonable conditions as may be specified by the person giving it but shall not be unreasonably withheld.
(4) In this paragraph “navigation authority” means any person who has a duty or power under any enactment to work, maintain, conserve, improve or control any canal or other inland navigation, navigable river, estuary, harbour or dock.