Remutaka Tunnel facts for kids

The Remutaka Tunnel (which was called Rimutaka Tunnel before 2017) is a long railway tunnel in New Zealand. It goes through the Remutaka Range of mountains. This tunnel connects Maymorn, near Upper Hutt, with Featherston. It's an important part of the Wairarapa Line railway.

The tunnel opened on 3 November 1955. It is about 8.9 kilometers (5.5 miles) long. For a while, it was the longest tunnel in New Zealand! It took over from the Otira Tunnel in the South Island. Later, the Kaimai Tunnel (9.0 kilometers or 5.6 miles) became the longest in 1978. But the Remutaka Tunnel is still the longest one in New Zealand that has regular passenger trains.

Building the Remutaka Tunnel

The Remutaka Tunnel was built to replace an old, difficult railway route called the Rimutaka Incline. This old route used special Fell engines and was very expensive to run.

Why a New Tunnel Was Needed

People often complained about the original railway line between Upper Hutt and Featherston, even before it was finished. In 1898, J. H. Dobson looked into other possible routes. By 1900, a 5-mile (8 km) tunnel seemed like a good idea. But it was too expensive to build at that time.

In the 1920s, people started pushing for a replacement again. Studies were done in 1921-22 to check distances and costs. Many routes were looked at, but nothing happened right away. Then, in 1936, the new Labour government decided to go ahead with the tunnel plan. Detailed surveys were finished in 1938-1939. However, the project was put on hold again because of World War II.

After the war, building a new route became very urgent. The old H class locomotives were getting old, and the Incline itself was in bad shape. Maintenance costs were also going up. Between 1945 and 1947, four options were considered. Everyone agreed that only a tunnel under the Remutaka Ranges would work. The chosen route was the shortest one. It would be a tunnel between Mangaroa and Lucena’s Creek gully.

How the Tunnel Was Built

Construction began in 1948. The Public Works Department started digging from both ends. They dug about 1054 feet (321 meters) from the west and 820 feet (250 meters) from the east. A big contract to finish the tunnel was given to a group called Morrison Knudsen and Downer (MKD) on 7 May 1951.

Work started at the west end in July 1951 and at the east end in August. The companies thought it would take four years to complete. But the two digging teams met in the middle on 20 April 1954! The concrete lining inside the tunnel was finished a month later. Part of the tunnel was built using a "full face" method. This meant digging out the whole tunnel shape at once, instead of digging in smaller sections. Much of the dirt and rock from the west side was used to build the Maymorn station area.

About 600 people worked for MKD on the tunnel. At any one time, there were usually 300 to 400 workers. Most of them were single men. They lived in huts or bunkhouses at the Mangaroa or Featherston entrances. These camps had kitchens and dining halls. There were also 20 houses at each site for married staff. Sadly, three workers lost their lives during the tunnel's construction.

New Zealand Railways took over the tunnel on 1 February 1955. This included the paths leading to the tunnel and bridge supports. Track laying began then. By October 1955, all the tracks were laid. Signalling and traffic control equipment were also installed. On 29 October, all trains on the old Upper Hutt to Featherston section stopped. Over the next three days, the old railway line was removed. The new path was finished, and the last part of the track was laid. On 3 November 1955, the new line opened. Two special trains traveled from Wellington for the opening ceremony.

Tunnel Design and Features

The new railway line has a gentle slope of 1 in 70. The tightest curve is 400 meters (about a quarter-mile) wide. The tunnel goes up slightly from the western entrance. It reaches its highest point about halfway through. Then it goes down towards the eastern entrance.

The tunnel is 5.18 meters (17 feet) high inside. It is 4.68 meters (15 feet 4 inches) wide. It is lined with concrete that is at least 38 centimeters (15 inches) thick. When the two ends of the tunnel met on 20 April 1954, the surveying error was very small. It was only 44.5 millimeters (1.75 inches)! The tunnel was planned to make the journey between Upper Hutt and Featherston much shorter. It cut the distance from about 24 miles (39 km) to about 15 miles (24 km).

After the tunnel was finished, a large vertical ventilation shaft was built. It is 2.74 meters (9 feet) wide. This shaft goes up from almost the middle of the tunnel to the surface. It comes out near the Remutaka Rail Trail. The shaft is 117 meters (380 feet) high. It was built because tests showed the tunnel wouldn't have enough natural airflow if diesel trains were used. Originally, they thought about using electric trains. But studies showed that diesel trains would be cheaper.

The new railway line also included two places for trains to pass each other. These were at the new Maymorn Railway Station and the Rimutaka Loop at the tunnel's eastern entrance. There are also four bridges. One is a 91-meter (300 ft) bridge over the Mangaroa River. There is also another tunnel and two underpasses near Maoribank.

The Maoribank Tunnel is 555 meters (1,821 feet) long. Work on it started in October 1953 and finished in December 1954. On the eastern side, two short tunnels were planned. But it was cheaper to make the line 140 meters (459 feet) longer and have open cuttings instead.

Building the Remutaka Tunnel used a lot of materials:

• Gelignite (explosive): 299,258 kg (659,750 lbs)
• Detonators (to set off explosives): 327,850
• Diesel fuel: 3,182,264 liters (700,000 imperial gallons)
• Cement: 26,163 tonnes (25,750 tons)
• Aggregate (gravel, sand): 87,837 cubic meters (114,886 cubic yards)
• Timber (wood): 15,820 cubic meters (6,703,533 super feet)

How the Tunnel Is Used Today

Types of Trains

The first trains to use the tunnel were the 560 kW DG class diesel locomotives. Steam trains could not use the tunnel because it was too long. The smoke would be dangerous in the enclosed space. This made the Wairarapa Line the first railway line in New Zealand to use only diesel trains. Today, DC, DFT, and DX class diesel locomotives run on this route.

There have been ideas to make the tunnel and the Wairarapa line electric. This would be an extension of the electric train system in Wellington. The tunnel was designed so that electric wires could be installed. But this has not happened. The electric wires currently stop just north of Upper Hutt station. In 2007, the Greater Wellington Regional Council decided not to electrify the tunnel. They said there weren't enough passengers to make it worth the cost. They also said the tunnel would "have to be made bigger."

Train Services

Passenger Trains

Transdev Wellington runs passenger trains called the Wairarapa Connection. These trains travel between Wellington and Masterton through the Remutaka Tunnel. They run five times a day each way from Monday to Thursday. On Fridays, they run six times a day. On Saturdays, Sundays, and public holidays, they run twice a day each way. Special trains also use the tunnel. These include trains for railway fans and trains going to the Toast Martinborough festival.

If a steam-hauled excursion train wants to go through the tunnel, a diesel locomotive must pull it. This is because of the danger from smoke in the long, enclosed tunnel. Since 2014, diesel locomotives pulling passenger trains in long tunnels must have special fire safety equipment. This rule came after the Pike River Mine disaster inquiry. At first, DC class locomotives were used for the Wairarapa Connection. Then, from 2015, DFB class locomotives were used.

Freight Trains

The tunnel is also used for freight trains. These trains carry goods from the Wairarapa region to Wellington. They often carry logs from local pine forests. They also transport wood products from the Juken New Zealand Ltd timber mill at Waingawa, which is just south of Masterton.

See also

In Spanish: Túnel de Rimutaka para niños