State Highway 73 (SH 73) is a major east-west South Island state highway in New Zealand connecting Christchurch on the east coast with Cass/Hokitika via the Southern Alps. It is mostly two lane, with some single-lane bridges north of Springfield but is mostly dual carriageway in Christchurch. The fourth and fifth-highest points of New Zealand's state highway network are on this road at Porters Pass and Arthur's Pass respectively.

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State Highway 73
Route information
Maintained by NZ Transport Agency
Length	231 km (144 mi)
Tourist routes	Great Alpine Highway Christchurch Ring Road Inland Scenic Route between Sheffield and Waddington.
Major junctions
Northwest end	SH 6 at Kumara Junction
Southeast end	SH 75 (Curletts Road)/ SH 76 (Christchurch Southern Motorway) at Middleton, New Zealand
Location
Country	New Zealand
Primary destinations	Kumara, Dillmanstown, Jacksons, Otira, Arthur's Pass, Bealey, Cass, Castle Hill Village, Springfield, Sheffield, Waddington, Darfield, Kirwee, Aylesbury, West Melton, Yaldhurst, Christchurch
Highway system
New Zealand state highways Motorways and expressways List
← SH 71 → SH 74

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The route connecting the West and East coasts of the South Island via the Southern Alps were known for hundreds of years by the Māori people, due to a flourishing pounamu trade. The Europeans were informed of the route by a local chief in the mid-19th century but was not used during his lifetime. In 1864, Arthur Dudley Dobson traversed from the east to the west coast from the Waimakariri River, thereby discovering Arthur's Pass. A route connecting Christchurch to Hokitika was fully completed in 1866, with the first Cobb & Co coach began operating that same year for the burgeoning gold rush.

Construction of a rail link had started in 1890, and the Midland Line between Canterbury and the West Coast was finally completed on 4 August 1923, with the opening of the Otira Tunnel. This signalled the end of the Cobb & Co coach in New Zealand.^[1] When the section of the line from Springfield to Broken River in Canterbury was opened in 1906, it was then possible to travel from Canterbury to the West Coast in a single day with a 40-mile (64 km) coach journey between the railheads at Broken River and Otira.

Due to the geography and topography between Springfield and Kumara, the road has been subjected to several closures and road realignments, with both Porters and Arthur's Pass subjected to frequent closures during the winter months. The road between Arthur's Pass and Otira in particular was amongst the most dangerous in the country, due to the road located on scree slopes which frequently gave way. As a result, numerous studies were conducted into alternative options for fixing the road around Candy's Bend, Starvation Point and the Zig Zag. Construction of the Otira Viaduct and the protective roofs from slips began in 1997 and opened in 1999.^[2]

Over the past 40 years SH 73 has been subjected to several route changes both in the Christchurch and the Arthur's Pass-Otira areas. In the early years SH 73 originally ended at the Blenheim Road and Hansons Lane corner in Upper Riccarton. In 1999, one of the worst sections of highway in the country (around Candy's Bend) were replaced with the Otira Viaduct. Meanwhile, in Christchurch, since SH 1 was rerouted to bypass the CBD, SH 73 was extended to Brougham Street/Waltham Road intersection, with the rest of the route covered by SH 74.

In 2004, with SH 74 being rerouted to run along the Ring Road and the entire length of Tunnel Road instead of through the CBD, SH 73 was extended further to the Port Hills Road interchange on SH 74. It was also rerouted from the intersection of Blenheim Road to follow Curletts Road and Yaldhurst Road, instead of via Main South Road through Hornby, meeting back again with SH 1 at the intersection of Masham and Russley Roads.^[4]

As of December 2012, with the extension of the Christchurch Southern Motorway, the section of SH 73 east of Curletts Road was re-gazetted as SH 76 in line with the new motorway extension.

State Highway 73A was a spur section of SH 73 connecting the suburbs of Hornby, New Zealand and Sockburn, New Zealand via Main South Road and Blenheim Road. Before 2004 it formed part of the old route of SH 73 and further before that SH 1. It was one of the few state highways in New Zealand to be wholly dual carriageway. In 2014, the entire highway has been revoked due to completion of the Christchurch Southern Motorway (gazetted SH 76 in 2012) which runs almost parallel to this route.^[5]

• List of New Zealand state highways