Rimutaka Tunnel
Encyclopedia
The Rimutaka Tunnel is a railway tunnel
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

 through New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

's Rimutaka Ranges, between Maymorn
Maymorn
Maymorn is a rural area of Upper Hutt city in the Wellington region of New Zealand. For statistical purposes, Maymorn is counted as part of Te Marua in the New Zealand census. The usual resident 2006 population of this area was 1,068...

, near Upper Hutt
Upper Hutt
Upper Hutt is a satellite city of Wellington. It is New Zealand's smallest city by population, the second largest by land area. It is in Greater Wellington.-Geography:Upper Hutt is 30 km north-east of Wellington...

, and Featherston
Featherston, New Zealand
Featherston is a town in the north of the Wellington Region region of New Zealand. It lies in the Wairarapa, just north of the Rimutaka Tunnel, in the South Wairarapa District. The population was 2,340 in the 2006 Census....

, on the Wairarapa Line
Wairarapa Line
The Wairarapa Line is a secondary railway line in the south-east of the North Island of New Zealand, connecting the capital city of Wellington with the Wairarapa region. The line ends at Woodville, where it joins the Palmerston North - Gisborne Line...

.

The tunnel, which was opened to traffic on 3 November 1955, is 8.798 kilometres (5.5 mi) long. It was the longest tunnel in New Zealand, superseding the Otira Tunnel
Otira Tunnel
The Otira Tunnel is a railway tunnel on the Midland Line in the South Island of New Zealand between Otira and Arthur's Pass. It runs under the Southern Alps from Arthur's Pass to Otira - a length of over . The gradient is mainly 1 in 33, and the Otira end of the tunnel is over lower than the...

 in the South Island until the completion of the Kaimai Tunnel
Kaimai Tunnel
The Kaimai Tunnel is a railway tunnel through the Kaimai Range in the North Island of New Zealand. Since it was opened in 1978, it has held the title of longest tunnel in New Zealand, assuming this distinction from the previous title holder, the Rimutaka Tunnel...

 (8.88 km, 5.55 miles) near Tauranga
Tauranga
Tauranga is the most populous city in the Bay of Plenty region, in the North Island of New Zealand.It was settled by Europeans in the early 19th century and was constituted as a city in 1963...

 in 1978. Rimutaka remains the longest tunnel in New Zealand with scheduled passenger trains.
  • West portal: 41°6′28.36"S 175°8′22.18"E
  • East portal: 41°7′57.8"S 175°14′23.31"E

History

The tunnel was built as part of a deviation to replace the costly Rimutaka Incline and its Fell engines
Fell mountain railway system
The Fell system uses a raised centre rail between the two running rails on steeply-graded railway lines to provide extra traction and braking, or braking alone. Trains are propelled by wheels or braked by shoes pressed horizontally onto the centre rail, as well as by means of the normal running...

.

Background

The original route between Upper Hutt and Featherston was often the subject of criticism, even before it was built. In 1898 J. H. Dobson completed several surveys on behalf of the Public Works Department into possible alternatives. Conclusions reached in 1899 as a result of these surveys did little more than confirm previous opinions. One promising possibility was a 5 miles (8 km) tunnel between Mangaroa and Cross Creek, which received so much attention that it nearly became the much-sought deviation. By 1900, however, it was realised that the cost of constructing such a tunnel could not be contemplated at that time.

It was not until the 1920s that significant campaigning for a replacement again prevailed on the government. In 1921-22 a feasibility study was conducted, including distances and estimated costs. Several routes were considered, including variations on previous ideas, but nothing more was done at the time.

The new Labour
New Zealand Labour Party
The New Zealand Labour Party is a New Zealand political party. It describes itself as centre-left and socially progressive and has been one of the two primary parties of New Zealand politics since 1935....

 government of 1936 announced its intention to proceed with the Mangaroa to Cross Creek tunnel. Detailed surveys were completed in 1938/1939, but the project was again postponed due to World War II.

After World War II it became a matter of urgency to consider a replacement. The H class locomotives were showing their age, the Incline was in bad shape, and maintenance costs were increasing. Between September 1945 and July 1947 four options were considered. It was accepted that no contour line could be the solution and that a tunnel under the Rimutaka Ranges was the only satisfactory answer. The adopted route was the shortest route, a tunnel between Mangaroa and Lucena’s Creek gully.

Construction

The first shot was fired in 1948 when the Public Works Department started the tunnel with bores of 1054 feet (321.3 m) at the western end and 820 feet (249.9 m) at the eastern end. A contract for completing the tunnel was let to a consortium of Morrison Knudsen Inc. and Downer and Company on 7 May 1951. The work commenced at the west end in July 1951 and at the east end in August. The contract was expected to be completed in four years, but the headings met on 20 April 1954 with the concrete lining finished a month later.

New Zealand Railways took possession of the tunnel on 1 February 1955, which also included approach formations and bridge piers, at which time track laying commenced. By October 1955 the signalling and centralised traffic control equipment had been installed and all the track was laid, except for a short section near Upper Hutt where the old line crossed the new line at a higher level. All traffic on the Upper Hutt to Featherston section was suspended after the arrival of the Carterton Show Day excursion train at Upper Hutt on the evening of Saturday 29 October. Over the next three days the old formation was removed, the cutting for the new formation completed and the remainder of the track laid. On Thursday, 3 November, the new line was opened and two special trains travelled from Wellington to Speedy’s Crossing to the inauguration ceremony.

Design

The deviation's ruling grade is 1 in 70, compensated for curvature. The tunnel rises at 1 in 400 from the western portal to the highest point on the deviation, roughly halfway through the tunnel, and then descends to the eastern portal at 1 in 180. It has an internal height of 5.18 metres (17 ft) and a width of 4.68 metres (15 feet 4 inches); it is lined with concrete with a minimum thickness of 38 cm (15 inches) inside the face of the excavation. When the tunnel holed through on 20 April 1954 the surveying error was found to be only 44.5 mm (1.75 inches).

After its completion, a 2.74 metre (9 ft) diameter vertical ventilation shaft was driven up from a point almost halfway through the tunnel. It reaches the surface beside the Rimutaka Rail Trail
Rimutaka Rail Trail
The Rimutaka Rail Trail is a walking and cycling track in the North Island of New Zealand. It runs between Maymorn and Cross Creek, and follows of the original route of the Wairarapa Line over the Rimutaka Ranges between the Mangaroa Valley and the Wairarapa, including the world-famous Rimutaka...

 near the former route's Pakuratahi Tunnel. The 117 metre (380 ft) high shaft was constructed after tests showed that the tunnel would not generate enough natural ventilation without it. The original specification using electric locomotives did not require the level of ventilation that was required to clear the tunnel of exhaust fumes generated by the subsequently used diesel traction.

The construction of the Rimutaka Tunnel consumed:
  • Gelignite: 299,258 kg (659,750 lbs),
  • Detonators: 327,850,
  • Diesel fuel: 3,182,264 litres (700,000 imp. gallons),
  • Cement: 26,163 tonnes (25,750 tons),
  • Aggregate: 87,837 metres3 (114,886 cu. yd), and
  • Timber: 15,820 metres3 (6,703,533 super feet).

Diesel-Electric

The first locomotives to work through the tunnel were the 560 kW DG class
NZR DG class
The NZR DG and DH class locomotives were a class of diesel-electric locomotives used on New Zealand's national rail network, built by English Electric.- Introduction :...

 - the tunnel was too long for steam locomotives, making the Wairarapa Line
Wairarapa Line
The Wairarapa Line is a secondary railway line in the south-east of the North Island of New Zealand, connecting the capital city of Wellington with the Wairarapa region. The line ends at Woodville, where it joins the Palmerston North - Gisborne Line...

 the first fully dieselised line in New Zealand. Today, DBR
NZR DB class
The NZR Db diesel-electric locomotive class was built in 1965-1966. They were a lighter version of the Da class to operate on secondary North Island lines from which the Da was excluded due to its weight. One of the principal lines which the Db dominated was the East Coast Main Trunk to Tauranga...

, DC
NZR DC class
The NZR DC class locomotive is the most common class of locomotive currently in operation on the New Zealand rail network. Primarily employed to haul freight trains operated by KiwiRail, the class is also used for long-distance passenger trains operated by Tranz Scenic and suburban passenger trains...

 and DX
NZR DX class
The NZR DX class is a class of 49 Co-Co diesel-electric locomotives that currently operates on New Zealand's national railway network.Built by General Electric in Erie, Pennsylvania, United States, they were introduced to New Zealand between 1972 and 1976. The class is based on the General Electric...

 class locomotives run the route.

Steam

The annual Daffodil Carnival steam train from Wellington to Carterton
Carterton, New Zealand
Carterton is a small town in the Wellington Region of New Zealand and the seat of the Carterton District. It lies in a farming area of the Wairarapa in New Zealand's North Island. It is located southwest of Masterton and northeast of Wellington...

 has to be hauled by diesel-electrics attached to the front of the steam locomotive between Upper Hutt and Featherston, through the tunnel.

Electric

There have been proposals to electrify the tunnel and the Wairarapa line as far north as Masterton as an extension of the Wellington suburban electrification. The tunnel was designed to enable catenary to be installed but this has not happened, and the catenary finishes just north of Upper Hutt station.

Passenger

Tranz Metro
Tranz Metro
Tranz Metro, part of KiwiRail, is the operator of Metlink suburban trains owned by the Greater Wellington Regional Council in the Wellington Region of New Zealand....

 operates passenger services named the Wairarapa Connection between Wellington
Wellington
Wellington is the capital city and third most populous urban area of New Zealand, although it is likely to have surpassed Christchurch due to the exodus following the Canterbury Earthquake. It is at the southwestern tip of the North Island, between Cook Strait and the Rimutaka Range...

 and Masterton
Masterton
Masterton is a large town and local government district in the Wellington Region of New Zealand. It is the largest town in the Wairarapa, a region separated from Wellington by the Rimutaka ranges...

 via the tunnel five times a day each way Monday to Thursday, six on Friday, and twice a day each way on Saturday, Sunday, and public holidays. Excursion trains also go through the tunnel, such as railway enthusiast specials and trains to the Toast Martinborough festival. Steam-hauled
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

 excursions require diesel locomotive
Diesel locomotive
A diesel locomotive is a type of railroad locomotive in which the prime mover is a diesel engine, a reciprocating engine operating on the Diesel cycle as invented by Dr. Rudolf Diesel...

s to provide motive power through the tunnel due to the dangers of smoke in the tunnel's lengthy and confined conditions.

Freight

The tunnel is used for freight from the Wairarapa to Wellington, notably wood products from the Juken Nissho timber mill at Waingawa, just south of Masterton.
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