Dukes Highway is a 190 kilometre^[1] highway corridor inSouth Australia, which is part of the link between the Australian cities ofAdelaide andMelbourne. It is part of theNational Highway system spanning Australia, and is signed as route A8.

Dukes Highway South Australia
Northwest end Southeast end
Coordinates	35°16′20″S139°27′35″E / 35.272343°S 139.459762°E /-35.272343; 139.459762 (Northwest end) 36°20′39″S140°58′02″E / 36.344113°S 140.967105°E /-36.344113; 140.967105 (Southeast end)
General information
Type	Highway
Length	190 km (118 mi)[1]
Route number(s)	A8(2017–present) Entire route Concurrencies: B57(1998–present) (Cannawigara–Bordertown)
Former route number	National Highway A8(1998–2017) National Highway 8(1974–1998) National Route 8(1955–1974)
Major junctions
Northwest end	Princes Highway Tailem Bend, South Australia
	Mallee Highway Riddoch Highway Ngarkat Highway
Southeast end	Western Highway SA/VIC border
Location(s)
Region	Murray and Mallee,Limestone Coast[2]
Major settlements	Coonalpyn,Keith,Bordertown
Highway system
Highways in Australia National Highway •Freeways in Australia Highways in South Australia

Dukes Highway begins at the intersection withPrinces Highway inTailem Bend. It heads in a southeast direction to the state border withVictoria just east ofBordertown, continuing into Victoria asWestern Highway, with the same route signage (route A8). It is mostly a single carriageway of one lane each way, with 36overtaking lanes.^[3] Approximately 90 kilometres (56 mi) has 'wide centre lines', providing a 1.2 metres (3 ft 11 in) boundary between traffic travelling in opposite directions.^[4]

Generally, the quality of Dukes Highway is of a high standard, with the entire road having wide lane widths andsealed shoulders with at least five (and usually six) metres clear beyond the edge line.^[5] There are 16 rest areas or parking bays along the Dukes Highway, at approximately 15 km intervals. Each one provides sealed parking space for at least fourB-double trucks, with bins, tables, shelter and lighting.^[6]

Dukes Highway runs through the northern part of theLimestone Coast region of South Australia. The route and many of the settlements, including Bordertown, were established in the 1850s to supply water to horses for the gold escorts from the Victorian goldfields to Adelaide.^[7]

Gold was taken to Adelaide rather than the closer Melbourne because a higher price was offered there. The higher price was offered to stop the South Australian economy from collapsing, as all the labourers were heading to the Victorian Goldfields. TheBullion Act was passed and anAssay office was established in Adelaide for the assaying and stamping of gold in 1852. It is claimed that this saved South Australia from bankruptcy.^[8]

By the 1930s, the series of separate tracks had started to coalesce into the route it follows today, and was already being referred to as "the Duke's Highway" – after theDuke of York, later KingGeorge VI^[9] – but at the time the name had never been officially recognised. There was a push to name the road Tolmer Highway, after former police commissionerAlexander Tolmer of gold escort fame, but this never eventuated.^[9]

In the latter half of the 20th century, the western end of Dukes Highway was realigned to meet theMallee Highway closer to Tailem Bend. It previously ran north fromCoomandook on the alignment that is now known as theOld Dukes Highway toMoorlands.^[10]

The final 17 km of the highway after Bordertown, was originally built on unstable ground, and was re-constructed in 2005.^[11]

Dukes Highway is South Australia's deadliest major road, with 28 deaths in the 5 years to 2009.^[12] This has led to calls for road improvements to separate traffic in each direction with adual carriageway.^[13] Point-to-point speed cameras have been installed on one section of the highway to identify drivers who flout the speed limit.^[14]

Parts of the highway have wider centre lines installed, with audio tactile treatment to help drivers to realise and recover from drifting across the centre line before they encounter an oncoming vehicle. This is intended to reduce fatigue and inattention-related crashes.^[15]

• Highways in Australia
• Highways in Victoria
• List of highways in South Australia