Castlereagh Highway

Castlereagh Highway Gazetted		August 1928 (NSW, as Main Road 56)[2] March 1938 (NSW, as State Highway 18)[3]
Route number(s)	A55 (2005–present) (St George–QLD/NSW border) B55 (2013–present) (QLD/NSW border–Marrangaroo)
Former route number	National Route 55 (1997–2005) (St George–QLD/NSW border) National Route 55 (1974–2013) (QLD/NSW border–Gilgandra) State Route 86 (1974–2013) (Gilgandra–Marrangaroo)
Major junctions
North end	Carnarvon Highway St George, Queensland
	Gwydir Highway Kamilaroi Highway Newell Highway Oxley Highway Golden Highway
South end	Mudgee
Highway system
Highways in Australia National Highway • Freeways in Australia Highways in Queensland Highways in New South Wales

Castlereagh Highway is a 790-kilometre (490 mi)^[1] state highway located in New South Wales and Queensland, Australia. From north to south the highway traverses South West Queensland and the North West Slopes, Orana, and Central West regions of New South Wales.

The highway is part of the

The Department of Main Roads, which had succeeded the New South Wales MRB in 1932, declared State Highway 18 on 16 March 1938, from the intersection with State Highway 11 (later known as Oxley Highway) at Gilgandra via Coonamble and Walgett to the state border with Queensland near Brenda;^[3] with the declaration of State Highway 17 (later known as Newell Highway) on the same day,^[9] the northern end of Trunk Road 56 was truncated to meet State Highway 17 at Forbes, as a result.^[9] State Highway 18 was named Castlereagh Highway on 12 May 1954,^[10] after the Castlereagh River, with the river named in honour of Lord Castlereagh.^[11][12]

The alignment north of Lightning Ridge was altered on 17 June 1959 to meet the state border with Queensland at Hebel via Angledool, instead of via Brenda.^[13] In December 1982, a 15 kilometre deviation opened south of Mudgee as part of the Windamere Dam project.^[14]

The

The passing of the Roads Act of 1993[16] through the Parliament of New South Wales updated road classifications and the way they could be declared within New South Wales. Under this act, Castlereagh Highway today retains its declaration as Highway 18, from the state border with Queensland at Hebel to the intersection with Oxley Highway in Gilgrandra, then from the intersection with Newell Highway in Gilgandra to the intersection with Golden Highway in Dunedoo, then from the intersection with Golden Highway near Craboon to the interchange with Great Western Highway at Marrangaroo.^[17]

Within New South Wales, the highway was signed National Route 55 in 1974 from Gilgandra to Walgett, and State Route 86 south of Gilgandra; National Route 55 was extended north from Walgett to the border with Queensland in 1983. Queensland however signed Carnarvon Highway as National Route 55 between 1983 and 1997 rather than Castlereagh Highway, causing a major discrepancy for many years in that National Route 55 met the border at Hebel but abruptly begun again over 100 kilometres (62 mi) east along the border at Mungindi. The Queensland Road Department changed this in 1997 and signed National Route 55 over the border north to St George, and eventually to Charters Towers in later years. With both states' conversion to the newer alphanumeric system between 2005 and 2013, its route number was updated to route A7 between Rolleston and Roma and A55 between Roma and the state border for the highway within Queensland in 2005, and eventually along the remaining highway within New South Wales as route B55 in 2013.^[18]

Upgrades

The Roads of Strategic Importance initiative, last updated in March 2022, includes the following project for Castlereagh Highway.

Carnarvon Highway intersection upgrade

A project to upgrade the intersection with Carnarvon Highway at a cost of $3.4 million was completed in mid-2022.^[19] This project was targeted for "early works" by the Queensland Government.^[20]

Major junctions

State	LGA	Location	km[1]	mi	Destinations	Notes
Mungindi	Northern terminus of highway at T intersection, route A55 continues north along Castlereagh Highway
	Mungindi	T intersection
		88	55	Railway Street – Dirranbandi	T intersection
		90	56	Bollon–Dirranbandi Road – Bollon	T intersection
	Hebel	154	96	William Street – Goodooga	T intersection
		158	98	Castlereagh Highway	Southern terminus of route A55
State border				Queensland – New South Wales state border
Angledool	Castlereagh Highway	Northern terminus of route B55
	Collarenebri, Moree	T intersection; northern terminus of concurrency with route B76
	Barwon River		281	175	Dick O'Brien Bridge
	Walgett	Walgett	284	176	Narrabri	T intersection
	Namoi River		288	179	Bridge over the river (no known name)
	Walgett	Walgett	289	180	Brewarrina, Bourke	4-way intersection; southern terminus of concurrency with route B76
	Castlereagh River		404	251	Bridge over the river at Coonamble (no known name)
	Castlereagh River		462	287	Bridge over the river at Armatree (12 kilometres (7.5 mi) south of Gulargambone, no known name)
	Nevertire	T intersection
		501	311	Dubbo, Parkes	T intersection; northern terminus of concurrency with route A39
	Castlereagh River		501	311	Bridge over the river at Gilgandra (no known name)
	Gilgandra	Gilgandra	502	312	Coonabarabran	T intersection; southern terminus of concurrency with route A39
	Castlereagh River		541	336	Bridge over the river (12 kilometres (7.5 mi) west of Mendooran, no known name)
	Coonabarabran	T intersection
		Dubbo	T intersection; western terminus of concurrency with route B84
	Talbragar River		596	370	Bridge over the river (no known name)
	Dunedoo	601	373	Golden Highway (B84 east) – Merriwa, Singleton, Newcastle	T intersection; eastern terminus of concurrency with route B84
	Wialdra Creek		638	396	Bridge over the river (no known name)
	Cudgegong River		657	408	Holyoake Bridge (1km North of Mudgee)
	Mid-Western	Ilford	725	450	Bylong Valley Way – Kandos, Rylstone, Bylong, Sandy Hollow	T intersection
			727	452	Bathurst-Ilford Road – Sofala, Bathurst
	Sydney	Southern terminus of highway and route B55 at directional T interchange;
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Route transition

See also