New Zealand State Highway 1

North Island (SH 1N)

SH 1 starts at Cape Reinga, at the northwestern tip of the Aupouri Peninsula, and since April 2010 has been sealed (mainly with either chipseal or asphalt) for its entire length. From Waitiki Landing south of Cape Reinga, SH 1 travels down the central-eastern side of the peninsula to Kaitaia, New Zealand's northernmost town, before turning south-east across the Northland Peninsula on to Kawakawa in the Bay of Islands, and then south to the city of Whangarei, the largest urban area in Northland.

SH 1 then skirts the south-western Whangarei Harbour, nearing the coast briefly at Ruakaka, before proceeding down to wind through the Brynderwyn Hills before approaching the upper reaches of the Kaipara Harbour. The highway crosses into the Auckland Region, and passes through Wellsford and Warkworth, again heading for the east coast.

Near Puhoi, on the Hibiscus Coast, SH 1 becomes the Auckland Northern Motorway, the main road north of New Zealand's largest urban area. The first 7.5 km (4.7 mi) of the motorway is an automated toll road. At Orewa, the motorway becomes toll-free, crossing farmland to the North Shore of Auckland. The road crosses through suburbs to the Waitemata Harbour, which it briefly follows before crossing it by the Auckland Harbour Bridge. The motorway comes off the bridge into Auckland's city centre, and forms its western boundary as SH 1 proceeds to the Central Motorway Junction.

At this junction, SH 1 becomes the Auckland Southern Motorway, and, after sweeping around the southern end of central Auckland, proceeds in a south-easterly direction. The section from the Central Motorway Junction and the Newmarket Viaduct, 3 km (1.9 mi) to the south, is the country's busiest section of road, with more than 200,000 vehicle movements a day between Khyber Pass Road and Gillies Ave. The motorway continues in a broadly southeast direction across the Auckland isthmus, then through Manukau and Papakura to the top of the Bombay Hills, just short of the Auckland/Waikato boundary.

At Bombay, SH 1 becomes the Waikato Expressway, a four-lane dual-carriageway expressway. The expressway takes the highway down the Bombay Hills to Mercer, where SH 1 meets the Waikato River, which it broadly follows for the next 220 km (140 mi). The Waikato Expressway temporarily ends at Longswamp and becomes a three-laned dual carriageway, resuming at Te Kauwhata before reverting to single carriageway just south of Ohinewai.

SH 1 runs as a single carriageway through Huntly to Taupiri, where the Waikato Expressway resumes. The expressway ends in north-western Hamilton. The highway bypasses the city centre to the west, before crossing to the east side and proceeding south-east out of the city. The expressway resumes at Tamahere, bypassing Cambridge to the north before reverting to a single carriageway east of the town. The highway continues eastward to the town of Tirau, where it turns south to pass through Putaruru and Tokoroa and the surrounding exotic pine plantation forest area.

At Wairakei, SH 1 takes an eastern route to bypass Taupo and meet the Lake Taupo shoreline south of the town near the airport. SH 1 follows the eastern shore of the lake for 50 km (31 mi) to Turangi, at the southern end of the lake.

Turning southwards again, SH 1 leaves Turangi and ascends onto the North Island Volcanic Plateau, passing through the fringes of the Tongariro National Park and into the Rangipo Desert, passing the volcanoes of Ruapehu, Ngauruhoe and Tongariro. The road between Rangipo (10 km (6.2 mi) south of Turangi) and Waiouru is commonly known as the Desert Road, and is frequently closed by snow during winter. At km 794 on the Desert Road, SH 1 is 1,074 metres (3,524 ft) above sea level - the highest point on the New Zealand State Highway network. SH 1 enters the Manawatu-Wanganui Region, and descends through an army training area to the end of the Desert Road at Waiouru.

From Waiouru, the highway follows tributaries of the Rangitikei River through Taihape to meet the main river at Utiku. It then follows the western bank of the Rangitikei through Ohingaiti and Hunterville to Bulls. At Bulls, SH 1 turns southeast to cross the river, turning southwest again 5 km (3.1 mi) down the road at Sanson. SH 1 crosses the Manawatu Plain, passing the city of Palmerston North about 20 km (12 mi) west of it. It passes through Foxton, before reaching the end of the plain at Levin.

From Levin, SH 1 follows the narrowing western coastal plain southwards. The highway crosses into the Wellington Region 15 km (9 mi) south of Levin, before passing through Otaki. At Peka Peka, SH 1 widens to a four-lane dual carriageway known as the Kapiti Expressway. The highway bypasses the Kapiti conurbation of Waikanae, Paraparaumu and Raumati, narrowing again to a two-lane single carriageway south of Mackays Crossing and passing through Paekakariki.

Between Paekakariki and Pukerua Bay, SH 1 and the North Island Main Trunk rail line travel along a narrow strip of land between the hills and the sea. The Centennial Highway, as it is known, is a narrow two-lane road that was highly accident prone until a centreline wire rope crash barrier was installed. Travelling through Pukerua Bay, the road becomes dual carriageway once more to Plimmerton, narrowing to single carriageway through the northern suburbs of Porirua to Paremata.

At Paremata, SH 1 resumes as dual carriageway along the edge of the Porirua Harbour to Porirua city centre. At Porirua, the highway becomes the Johnsonville-Porirua Motorway, and travels into the northern suburbs of Wellington, New Zealand's capital city. The motorway ends at Johnsonville, and SH 1 descends through the Ngauranga Gorge to the Ngauranga Interchange, on the shore of Wellington Harbour. At the interchange, traffic leaves for the Cook Strait ferries to Picton and the South Island.

At Ngauranga, SH 1 becomes the Wellington Urban Motorway, skirting the shore of the harbour then passing the city centre to the west. The motorway ends at Te Aro, where a one-way system takes traffic to the Basin Reserve. Northbound traffic uses the Wellington Inner City Bypass (opened 2007), while southbound traffic uses Vivian Street. From the Basin Reserve, SH 1 travels through the Mount Victoria Tunnel to Wellington's eastern suburbs and Wellington International Airport. SH 1 ends at a roundabout at the entrance to the airport.

South Island (SH 1S)

From the Picton Ferry terminal, SH 1 is steep, crossing a saddle into the valley of the Tuamarina River. It descends alongside this river and across the Wairau Plain before reaching Blenheim. From Blenheim the road travels briefly through some of Marlborough's famous vineyards, then passes the lower slopes of the steep Kaikoura Ranges where the road has occasional glimpses of the sea to the east over Lake Grassmere. This stretch is one of the most scenic, with the Pacific Ocean on one side and 2,500 m (8,200 ft) peaks on the other. From the small town of Ward the highway heads to the coast and follows it to Kaikoura. After passing Kaikoura, it veers inland, twisting tortuously through the Hundalee Ranges before emerging at the northern end of the Canterbury Plains.

The section of highway between Ward and Cheviot has been closed since November 2016, due to damage from the 2016 Kaikoura earthquake.

SH 1 passes through Amberley and Woodend before becoming the Christchurch Northern Motorway and bypassing Kaiapoi to the west. The motorway crosses the Waimakariri River and ends just north of Belfast. SH 1 bypasses inner Christchurch to the north-west via the outer suburbs of Harewood, past the Christchurch International Airport, and Yaldhurst. At Hornby, the highway turns south-west and passes through Templeton and Rolleston.

South of Rolleston, SH 1 becomes virtually straight as it crosses the wide fan of the Canterbury plains, crossing the country's longest road bridge at Rakaia before reaching Ashburton, and then veering back towards the coast, which it reaches at Timaru. Between Ashburton and Timaru it crosses Rangitata Island in the Rangitata River.

South of Timaru, the road again passes through gentle hill country, staying close to the coast but largely out of sight of it. The road veers inland briefly, bypassing Waimate as it reaches the plains around the mouth of the Waitaki River, which it crosses to enter Otago. It passes through Oamaru, from where it turns inland briefly, crossing undulating hill country before again reaching the coast at Moeraki. From here the road again hugs the coast along Katiki Beach, remaining closer to the ocean than at any point since Kaikoura. The highway turns inland at Shag Point, passing through Palmerston and Waikouaiti.

South of Waikouaiti the road again becomes steep, rising sharply over the Kilmog hill before dropping down to the coast at Blueskin Bay, then rising again via Dunedin-Waitati Highway (a two- to four-lane carriageway which used to be designated a motorway) to the northern outskirts of Dunedin. From here it descends a steep, twisting stretch of Pine Hill Road through Pine Hill, before passing the University of Otago and heading through the city centre. For much of its route through Central Dunedin the highway is split into two separate northbound and southbound roads, part of the city's one-way street system. These roads traverse the central city 2-3 blocks southeast of the heart of the CBD. At the southern end of central Dunedin, the highway becomes the Caversham By-pass, which rises along the Caversham Valley before again becoming a motorway at the saddle of Lookout Point.

The four-lane motorway (Dunedin Southern Motorway) runs through Dunedin's southern suburbs until the interchange with SH 87 at Mosgiel. SH 1 then heads southwest across the Taieri Plains. The area between the Taieri and Waipori Rivers is flood-prone, and the highway crosses this on a major embankment known colloquially as the flood-free highway. SH 1 continues through gentle hill country and along the shore of Lake Waihola, then crosses the Tokomairaro Plains into Milton. South of Milton is a major junction with SH 8 at Clarksville Junction. SH 1 continues to cross rolling hill country to reach Balclutha.

From Balclutha, the highway turns west, veering briefly north as it heads inland to avoid the rough hills of The Catlins. It passes through the small town of Clinton before reaching the major provincial town of Gore. Because of the names of these two towns, this stretch of the highway was christened "The Presidential Highway" during the time of the Clinton-Gore administration in the United States. At Gore the highway crosses the Mataura River; from here the road again turns south to roughly follow the river. The highway passes through Mataura before turning west at Edendale. Many travellers choose to turn onto SH 93 at Clinton, as this route offers a shorter journey between Clinton and Mataura and bypasses Gore. Over its last stretch the road veers southwest before reaching the city of Invercargill. In central Invercargill it meets the southern end of SH 6 and turns due south, skirting the estuary of the New River and Bluff Harbour. It passes through the small town of Bluff before reaching its terminus at Stirling Point, a kilometre south of Bluff. A commemorative signpost at Stirling Point indicates distances to major world centres and to the start of the highway at Picton.

Spur sections

SH 1N has one spur, SH 1B from SH 1N at Taupiri to SH 1N at Cambridge, providing an eastern bypass of Hamilton.

SH 1S has one spur, SH 1D in Dunedin's southern suburbs, from SH 1S interchange at Abbotsford, passing through the suburbs of Sunnyvale and Fairfield before joining SH 1S at the Saddle Hill interchange. SH 1D was the former route of State Highway 1 before the completion of the Fairfield bypass motorway in 2003. It is a State Highway on paper only - it is not signposted as a State Highway, and it appears as a local arterial road on maps.

Road conditions

SH 1 has varied road conditions. For most of its length it is a two-lane single carriageway road with at-grade intersections and access, sealed with chipseal in rural areas or asphalt in urban and high-traffic areas. The highway has frequent passing lanes on these sections, to allow traffic to pass other vehicles safely. Parts of the road are steep by international standards. Most steep sections having a combination of passing lanes (uphill), and crawler lanes or stopping bays (downhill) to allow heavy and slow vehicles to pull out of the way to let other vehicles pass.

The New Zealand Transport Agency (NZTA) classifies the most part of State Highway 1 as a national strategic road. The exceptions are between Kawakawa and Whangarei and south of Mosgiel, where the SH 1 is classified as a regional strategic road, and north of Kawakawa where SH 1 is classified as a primary collector road. The sections between Wellsford and Wairakei, between Ohau and Wellington Airport, and between Woodend and Rolleston are classified as high volume roads.

NZTA announced in September 2010 that it was replacing the last three fords on SH 1S. The shingle fan fords are near Kaikoura, and while generally being dry, on about 28 days a year state highway traffic used to detour around them due to high water levels on old single-lane bridges, leading to delays on a major freight route. With the detour bridges reaching the end of their lifespan, NZTA replaced the fords with culverts.

Motorway and expressway upgrades

Construction of motorways and expressways has diverted the route of State Highway 1 in many places.

The opening of the Auckland Harbour Bridge and the Auckland Northern Motorway between Northcote Road and Fanshawe Street in May 1959 saw State Highway 1 diverted from its former route around the Waitemata Harbour. Northern extensions of the motorway in 1969 (to Tristram Avenue), 1979 (to Sunset Road) and 1984 (to Dairy Flat Highway via Greville Road) diverted State Highway 1 off Wairau Road and Albany Highway. A motorway extension from Greville Road to Silverdale in 1999 bypassed Dairy Flat Highway, which was re-designated State Highway 17. In 2009, the Northern Motorway was extended to Puhoi, bypassing Hibiscus Coast Highway through Orewa which was re-designated part of SH 17. However, SH 17 was short lived, being revoked in September 2012 and reverting to a local arterial road.

The Auckland Southern Motorway was built between 1953 and 1978, bypassing the former route via Great South Road. The construction of the Central Motorway Junction between 1973 and 1978 connected the Northern and Southern Motorways, taking State Highway 1 off inner Auckland streets.

The Waikato Expressway north of Te Kauwhata has largely been built on the existing line of SH 1N, although at Pokeno the highway was diverted to bypass the town to the east. South of Te Kauwhata, most of the expressway has been built on a new line bypassing the towns of Ohinewai, Ngaruawahia, Te Rapa and Cambridge, with old sections of SH 1N reverting to local arterial roads. The former route between Taupiri and Horotiu via Ngaruawahia was temporarily re-designated State Highway 1G before it could be transferred to the Waikato District Council.

The Wellington Urban Motorway was constructed between 1969 and 1978, but was originally part of State Highway 2 as it could only be accessed from the Hutt Valley. The construction of the Ngauranga Interchange flyovers in 1984 allowed SH 1 to be diverted onto the motorway, bypassing central Wellington streets.

The Christchurch Northern Motorway opened in 1967 between Pineacres and Belfast, bypassing the former route through Kaiapoi and providing a second road crossing of the Waimakariri River.

The extension of the Dunedin Southern Motorway has also seen changes in the highway, notably to bypass the suburbs of Fairfield and Sunnyvale.

Realignments

In Hamilton, SH 1N originally ran through the city centre rather than via Frankton. The original route was via Te Rapa Road, Ulster Street (first agreed as an alternative to the northern end of Victoria St in 1930), Victoria Street, Bridge Street and Cobham Drive, which is now Hamilton Urban Route 4. The current highway was diverted via Avalon Drive, Greenwood Street, Kahikatea Drive and Normandy Avenue in 1992.

The route north of Wellington known as the Centennial Highway from Ngauranga to Paekakariki was started in 1936 and opened on 4 November 1939. The Centennial Highway project involved an upgrade of the Ngauranga Gorge road and provided a new route from Paremata to Paekakariki, bypassing the winding road along the southern harbour edge from Paremata to Pauatahanui and the tortuous narrow winding Paekakariki Hill Road between Pauatahanui and Paekakariki. It followed a new route, bridging the narrow channel between Paremata and the Mana isthmus and following the eastern edge of the Taupo swamp north of Plimmerton before climbing to the Pukerua Bay saddle and descending to follow the coastline to Paekakariki.

In Porirua city, in the 1990s, the road was four-laned and realigned to ease curves from just south of Pukerua Bay to Mana. In 2005-2006, SH1 through Mana was upgraded with extra lanes to provide dual carriageways through Mana during peak periods and the installation of traffic lights to regulate cross traffic. A second bridge was added to four-lane the connection of the Mana isthmus to Paremata.

In Christchurch, SH 1S originally ran via the city centre rather than around the outskirts via Harewood. The original route was via Main North Road, Cranford Street, Sherborne Street, Bealey Avenue, Madras and Gasson Streets (north)/Barbadoes Street and Waltham Road (south), Brougham Street, the Christchurch Southern Arterial Motorway, Curletts Road, Blenheim Road, and Main South Road. The section from the Queen Elizabeth II Drive to Brougham Street is now a local road, while the remainder of the route forms parts of SH 74 and 76.

Re-routing also occurred in Whangarei and Timaru, removing SH 1 from their city centres. The original route through Whangarei via Kamo Road, Bank Street, Water Street and Maunu Road was diverted via Western Hills Drive, while the original route through Timaru via Stafford and King Streets was diverted via Theodosia Street and Craigie Avenue.

Most recently, the Taupo Bypass was constructed shifting the original SH 1 from the township and lakeside to the eastern outskirts of Taupo. The bypass starts at Wairakei near the existing SH 1/SH 5 intersection and finishes to the north of Taupo Airport. The concurrency with SH 5 also follows part of the bypass.

In the southern South Island, several particularly twisting sections of SH 1S have been rebuilt to remove sharp bends and to generally improve road conditions. These include stretches at Normanby, near Timaru; Waianakarua; at Tumai, near Palmerston; and on the Dunedin Northern Motorway near Waitati. An extensive section between Allanton and the Taieri River was realigned during the 1970s.

Former spurs

SH 1A ran from Orewa to Silverdale. When the Northern Gateway Toll Road opened, part of SH 1A was incorporated into SH 1N and the rest had its highway status revoked.

SH 1F was the name previously given to the northernmost section of SH 1N – between Cape Reinga and the junction with SH 10. This section is no longer a spur and is now part of SH 1N.

Future improvements

State Highway 1 has been earmarked for several motorway projects most of which have surfaced from the National governments Roads of National Significance package announced in 2009.

Auckland

The most controversial project is the Puhoi to Wellsford motorway (Ara Tūhono) . This is also referred to as the "Holiday Highway" as the current SH 1 becomes heavily congested in holiday periods from holidaymakers travelling to and from Auckland in the summer holiday season and public holiday weekends. Construction of the 18.5 km (11.5 mi) Puhoi to Warkworth section began on 8 December 2016 with the official sod-turning. The motorway will run west of the current SH 1 alignment, starting at the end of the existing Auckland Northern Motorway and terminating onto the existing highway at Kaipara Flats Road, north of Warkworth township. The new motorway is expected to open in late 2021. The NZTA released its preferred alignment for the Warkworth to Wellsford section for consultation in February 2017. The motorway will run from the Puhoi to Warkworth section west of Warkworth northward, passing east of Wellsford and Te Hana to terminate onto the existing highway at Mangawhai Road, just short of the Auckland/Northland boundary.

Many ideas have come forth to create a Second Harbour Crossing over Waitemata Harbour to complement the aging Auckland Harbour Bridge. These include ideas for a second bridge, or a second tunnel with capacity for rail. At this stage, any meaningful progress is unlikely until at least 2025.

Waikato

The Waikato Expressway has been under construction for much of the previous ten years, with most of the nine sections now funded or commencing construction. The Cambridge section which sees SH 1 bypass the township to the north was completed in late 2015. The two biggest most complex sections, the Huntly section which bypasses Huntly to the east of the township and the Hamilton section bypassing the city of Hamilton to the east, commenced construction in 2015 and 2016 respectively. All sections are estimated to be completed in 2020 meaning SH 1 from Puhoi (north of Auckland) to south of Cambridge will be entirely motorway or expressway, significantly reducing travel time through the Waikato Region by up to 35 minutes.

Kapiti/Wellington

The Peka Peka to Ōtaki extension to the Kapiti Expressway is due to start construction in mid 2017 and is expected to be completed in 2020. The project involves upgrading 13 km (8 mi) of State Highway 1 to a four-lane expressway, from end of the existing Kapiti Expressway at Peka Peka to Taylors Road north of Otaki.

The highly controversial Transmission Gully Motorway will connect Mackays to Linden, bypassing much of Porirua City, and is due to open in 2020.

Many inner city Wellington projects are also planned for SH 1 including duplication of the Terrace Tunnel and Mt Victoria tunnels. However these projects look uncertain as another planned project, the Basin Reserve Flyover failed to obtain the necessary resource consents and an appeal was rejected in the High Court.

Canterbury

NZTA are constructing the Western Belfast Bypass, a spur from the Christchurch Northern Motorway that will carry SH 1 traffic away from Belfast. Belfast is a significant congestion point on the northern corridor so the bypass will help relieve congestion for motorists traveling into Christchurch via Main North Road and also via SH 74 to the Lyttelton Port. The Western Belfast Bypass will be built to motorway status as far as the Groynes and is expected to be completed in 2018.

SH 1 to the west of Christchurch along Johns Road, Russley Road, Masham Road and Carmen Road is also being upgraded to four lanes from the Groynes to Main South Road in Hornby. Some sections have already been completed while the remaining sections are currently under construction. A grade separated interchange will also be built at the intersection of Memorial Avenue, the thoroughfare which connects the city to Christchurch International Airport.

NZTA are also investigating extending the Christchurch Northern Motorway so that it bypasses the town of Woodend.

Other improvements

Several smaller projects are being undertaken to improve sections of SH 1. These include: