North Island Main Trunk
| North Island Main Trunk | |
|---|---|
Map of the North Island Main Trunk | |
| Overview | |
| Status | Open |
| Owner | KiwiRail |
| Locale | North Island, New Zealand |
| Termini | |
| Service | |
| Type | Heavy rail |
| System | New Zealand railway network |
| Services | Northern Explorer, Capital Connection, Te Huia |
| Operator(s) | KiwiRail (freight) Great Journeys New Zealand (long-distance passenger) Transdev Wellington (Wellington–Waikanae commuter) Auckland One Rail (Pukekohe–Auckland commuter) |
| Rolling stock | EF class electric locomotives (Te Rapa – Palmerston North) |
| History | |
| Opened | 14 August 1908 (railheads meet) 6 November 1908 (official opening) 14 February 1909 (line completed) |
| Technical | |
| Line length | 681 km (423 mi) |
| Number of tracks | Triple track Wellington–Wairarapa Line junction double track Wairarapa Line junction–Pukerua Bay, Paekākāriki–Waikanae, Hamilton–Te Kauwhata, Amokura–Auckland Westfield – Wiri remainder single track |
| Character | Main line |
| Track gauge | 1,067 mm (3 ft 6 in) |
| Electrification | 1500 V DC overhead Wellington–Waikanae 25 kV 50 Hz AC overhead Palmerston North–Te Rapa, Pukekohe–Britomart |
| Operating speed | 110 km/h (68 mph) maximum |
| Highest elevation | 832 metres (2,730 ft) |
The North Island Main Trunk (NIMT) is the main railway line in the North Island of New Zealand, connecting the capital city Wellington with the country's largest city, Auckland. The line is 682 kilometres (424 mi) long, built to the New Zealand rail gauge of 1,067 mm (3 ft 6 in) and serves the large cities of Palmerston North and Hamilton.
Most of the NIMT is single track with frequent passing loops, but sections at each end that also handle suburban commuter traffic are double tracked:
- The section known as the North-South Junction between Wellington and Waikanae, except for 3.3 km (2.1 mi) of single-track through tunnels between North Junction (35.3 km (21.9 mi) from Wellington) and South Junction, (32 km (20 mi) from Wellington), on the Pukerua Bay to Paekākāriki section,
- between Hamilton and Te Kauwhata (except for the single-track Waikato River Bridge at Ngāruawāhia), and
- between Meremere and Auckland Britomart.
Around 460 km (290 mi) (approximately 65%) of the line is electrified in three separate sections: one section at 1500 V DC between Wellington and Waikanae, and two sections at 25 kV AC: 412 km (256 mi) between Palmerston North and Te Rapa (Hamilton) and 34 km (21 mi) between Pukekohe and Auckland Britomart.
The first section of what became the NIMT opened in 1873 in Auckland. Construction at the Wellington end began in 1885. The line was completed in 1908 and was fully operational by 1909. It is credited for having been an economic lifeline, and for having opened up the centre of the North Island to European settlement and investment. In the early days, a passenger journey between Wellington and Auckland could take more than 20 hours; today, it takes approximately 11 hours.
The NIMT has been described as an "engineering miracle", with numerous engineering feats such as viaducts, tunnels and a spiral built to overcome large elevation differences with grades suitable for steam engines, the ruling gradient being 1 in 50.