11. The promoter shall give to the engineer not less than 56 days' notice of its intention to—
(a)commence the construction of any specified or protective work, or
(b)exercise the powers conferred by article 20 (temporary closure of, and works in, waterways), except in case of emergency, when the promoter shall give such notice as may be reasonably practicable so that, in particular, the Board may where appropriate arrange for the publication of notices bringing the work to the attention of users of the Board’s network.