The passing of the
Main Roads Act of 1924 through the
Parliament of New South Wales provided for the declaration of Main Roads, roads partially funded by the State government through the
Main Roads Board (MRB).
Great Northern Highway was declared (as Main Road No. 9) on 8 August 1928, running from Kariong to Gosford (and continuing south via Peat's Ferry and
Hornsby to
North Sydney, and northwards via
Swansea and
Newcastle to
Hexham). With the passing of the
Main Roads (Amendment) Act of 1929 to provide for additional declarations of State Highways and Trunk Roads, this was amended to State Highway 9 on 8 April 1929. On 26 May 1931, it was re-declared as part of State Highway 10 and renamed
Pacific Highway. Main Road 335 was declared from
Long Jetty to
The Entrance (and continuing west via
Tumbi Umbi to
Tuggerah), and Main Road 336 was declared from the intersection with Main Road 335 at Long Jetty to the intersection with Pacific Highway at
Gosford, on the same day, 26 April 1933. Main Road 509 was declared from Wyee to the intersection with Pacific Highway in Doyalson on 27 September 1939, but was later extended past
Doyalson via
Budgewoi to
Noraville (and continuing west to the intersection with Pacific Highway at
Kanwal) on 4 April 1951; Main Road 335 was extended north, from The Entrance via
The Entrance North to the intersection with Main Road 509 in Noraville, on 22 February 1967, shortly before construction on the replacement
The Entrance Bridge commenced. The passing of the
Roads Act of 1993 through the
Parliament of New South Wales updated road classifications and the way they could be declared within New South Wales. Under this act,
Central Coast Highway was declared as Highway 30 on 9 August 2006, from the Gosford Interchange with
Pacific Motorway at Kariong via Gosford,
Erina,
Bateau Bay, The Entrance and Noraville to the intersection with Pacific Highway at Doyalson, subsuming Main Road 336; lengthening the existing gap of Highway 10 through Gosford (removed in November 1996) from Kariong to northern Gosford. The highway today, as Highway 30, still retains this declaration. As part of the original alignment of the former Pacific Highway, it was signed National Route 1 in 1955, and then replaced by State Route 83 in 1979, from Kariong to
Gosford. With the conversion to the newer alphanumeric system in 2013, this was replaced with route A49 for the entire length of the declared highway.
Upgrades A section of the highway between Carlton Road at
Erina and Ocean View Drive at
Wamberal was upgraded to two lanes per direction with a dividing median in 2012 and 2013. The intersections with Brisbane Water Drive and Manns Road were combined into a single intersection and completed in November 2015. , a section of the highway between Tumbi Road at
Wamberal and Bateau Bay Road at Bateau Bay is proposed to be upgraded to two lanes per direction with a dividing median. ==Major junctions==