 In October 1973 the Peats Ferry Bridge was duplicated as the Brooklyn Bridge, connecting the Berowra-Hawkesbury River and Hawkesbury River-Calga sections.Concurrently, the freeway was opened from to and to Wallarah Creek sections in December 1983, including the single carriageway motorway link from Wallarah Creek to the Pacific Highway at .The section between Calga and Somersby, including the new Mooney Mooney Creek bridge was opened on 14 December 1986, as thousands of people walked across the twin bridges.