Before the Ōtira Tunnel opened, passengers would travel over Arthur's Pass by coach (See DigitalNZ story)

When Midland rail line reached Ōtira in 1900 & Broken River from Christchurch in 1906, passengers transferred by coach

The first passenger train from Broken River to Christchurch

Engineering firm's workers used the "drill and blast" method to tunnel

In July 1909, tunnellers began working on the Bealey entrance at the Arthur's Pass end

Rail line was extended from Broken Hill's temporary terminus to the Arthur's Pass Station to the Bealey tunnel entrance

In 1912, with progress difficult & slow, the tunnelling was taken over by the Public Works Department

Close to 300 people travelled from Christchurch by special train & coaches arrived from West Coast for the ceremony

Minister of Public Works Sir William Fraser & ministerial party at the celebration of the piercing of the Ōtira Tunnel

Around 2.30pm, Fraser pulled down the ratchet to explode the last charge to open the hole to connect both ends of tunnel

The Union Jack was on display above the tunnel. The National Anthem was played after the ratchet was pulled.

Showing the 'piercing' ceremony of the Ōtira tunnel at the Canterbury side

After the ceremony, the coaches readied for departure back to the West Coast

Over the next three years, the tunnel's interior was concrete-lined

Between 1920-1923, a coal-fired power station was built near Ōtira entrance by English Electric of London

Due to its length, tunnel was electrified as steam engines would build up gas & monoxide in the tunnel

21 June 1923: One of the five new locomotives on a successful trial run at Ōtira Tunnel

In 1864, Arthur Dudley Dobson discovered an opening between the Southern Alp's mountains, now known as Arthur’s Pass

On either side of the pass are two deep gorges, the Bealey Gorge (eastern side) & the Otira Gorge (western side)

In 1865, a coach road was built over the Southern Alps

in 1884, NZ Govt passed an Act for a railway to be built between Christchurch, West Coast & Nelson by private enterprise

Sir Arthur Dudley Dobson, Alan Scott & C.Y. Fell visited London to interest financiers in promoting a company

The Company's contract was for building 376 km of railway between Christchurch & Nelson via Brunnerton (now Brunner)

It could either build a tunnel or an incline across Arthur's Pass & chose the latter as it would be quicker & cheaper

The Contract's clauses included the Company would pay c.£2,500,000 & build the railway within 10 years from 17 Jan 1885

For every 20 shillings the Company spent on construction, it would get 10 shillings of land from the Govt to sell

By 1887, the Company started the Brunnerton & Nelson sections of Midland Railway

(Image: Ceremony thought to be the turning the first sod at Brunnerton, which lies 12kms east of Greymouth)

In 1890, the Company began the Christchurch line; then ran out of money in 1894

Only 80 miles of the 235 miles (376 km) line had been completed with the capital raised in London by the Company

Govt seized Company's rail line & assets in May 1895 & following a Privy Council ruling took full ownership in May 1903

Under the Railways Construction and Land Act 1881, the Company's contract had expired & the work was incomplete

During 1895, the Public Works Dpt began working on the rail line & engineers decided to build the Ōtira Tunnel

Tunnel would be run from Otira (80km SW of Greymouth) to Arthur’s Pass settlement on eastern (Canterbury) side

In 1895, the New Zealand Railway Dpt (NZR) began operating trains on completed sections of the line

By 1900, the West Coast section of the rail line reached Ōtira

In 1906, when a temporary terminus was built at Broken River, coaches would travel to & from the Ōtira Station

Passengers were able to arrive for the NZ International Exhibition held in Christchurch from 1 Nov 1906 - 15 April 1907

1907: Engineering firm John McLean and Sons successfully tendered to build tunnel in 5 years (Image: Office at Ōtira)

1908: Workers' camp set up at the Ōtira end of the tunnel: 3.6 x 3m timber huts with canvas bunks for two people

Some of the workers named their huts: Otira Opera House, the Cafe de Paris, & the Do Drop Inn

During 1908, newspapers began reporting a series of strikes over working conditions & union involvement from West Coast

18 Nov 1908: A recreation hall for the tunnellers was erected. Number of workers at the camp peaked around 600.

1908: Construction of wooden pipes at the Stave Pipe Factory at Hokitika for the tunnel

17 Dec 1908: Some of the wooden stave pipes constructed at Hokitika ready for transporting

The wooden pipes were used to divert water from Holt's Creek to the power house built at Holt's Creek

The wooden pipes conveying water to the power house

Power house's generator drove a Pelton wheel connected to a dynamo putting out 433kW at 500 volts of direct current

The power house's dynamo charged the electrical equipment (eg compressor drills) used by the workers to build the tunnel

1908: Engineering staff at the mouth of the Ōtira tunnel

Used compressed-air drill to make 12 holes each 1.5m deep, packed them with gelignite, lit 1 metre fuse, & ran to safety

Workers divided tunnel into 2 sections: 1st team dug the bottom heading (6 x10 feet); then 2d team began the top heading

As tunnel sloped by 254m from east to west, most of excavation was at Ōtira as was easier to remove spoil & drain water

1909: Truck load of borings from tunnel as it reaches more than 25 chains (0.5 of a kilometre)

1909: Trucks with debris from the tunnel are run out on trestle bridge & then emptied over the side of 30ft embankment

1 July 1909: The mouth of the tunnel being constructed

One of the boring machines which the Government purchased for tunnelling

1909: Workers at the Ōtira Tunnel entrance

5 Aug 1909: Concrete arch being built with blocks made outside the tunnel that were allowed to mature for 3 months

During 1909, further strike action taken by workers

In 1910, Cass terminus opened in Selwyn district in Canterbury & coaches transported passengers between Ōtira & Cass

21 April 1910: Preparing the Bealey entrance of the tunnel at the Arthur's Pass end

Fresh air is supplied through 16 inch pipe by a rotary blower at each end of the tunnel

On 2 May 1910, part of the roof collapsed about two chains inside the Bealey entrance trapping 10 workers

As tunnel's entrance could collapse, a drive (23ft long x 4.5ft high x 4ft breadth) was made in hillside to free the men

Eight of the 10 workers were rescued within hours

The first cart away for Ōtira with the wounded and the nurse. (One person later died of his injuries.)

Rescuers had to drill through hard rock at right angles to reach the last two imprisoned workers

An opening was made in the air pipe & compressed air used to send food to the two trapped men

Rescuers with the last two workers who were rescued four days later

The two rescued workers

1910: View of tunnel entrance at Bealey Flat

By 23 Feb 1910, Ōtira section had reached a mile long, & the Bealey end a half a mile from the entrance

7 July 1910: 8 trucks on trestle bridge were struck by a runaway locomotive & fell 30 feet into creek bed

2 March 1911: Trucks carry rocks out of the tunnel

23 Nov 1911: The 4 o'clock shift going into work

30 Nov 1911: During a snowstorm, a train of trucks that were on the trestle bridge were wrecked

In Jan 1912, buildings near the Ōtira Tunnel entrance were destroyed by fire

View of the big sheds destroyed by fire

Feb 1912: View of entrance from gorge of Rolleston River with tracks leading from the Ōtira Station

As tenders for a new contractor were unsuccessful, Public Works Dept staff continued the tunnelling work

1913: A train load of explosives and timber to be used in the construction of the tunnel

1914: Canterbury end of the tunnel under construction

In 1914, Arthur's Pass railway station opened on the Midland Railway on the Canterbury side

1917: Tunnellers at work with drilling equipment including a pick axe. Hand-lamps were used for lighting.

Dec 1917: View of Bealey entrance where railway lines have been laid from Arthur's Pass Station

People assembled for the 'piercing' of the the two ends of the tunnel

29 Aug 1918: A view of three tunnels on the approach to Arthur's Pass

29 Aug 1918: View of the entrance to the Ōtira tunnel, from the Westland side

19 Sept 1918: Main street of Bealey Flat, showing some of the dwellings of the tunnel workers in winter

c.1919: Entrance to the Ōtira tunnel, as seen from the inside

c.1920: Ōtira Tunnel entranceway with workers relaxing outside

c.1920: Railway bridge and western portal area of the Ōtira tunnel

5 Aug 1920: The Bealey River showing where the tunnel enters the hill near the Arthur's Pass Station

Decision made to electrify tunnel due to its steep grade & length which would build up smoke from steam locomotives

At both entrances, the steam locomotives would be detached from the trains & electric locomotives substituted

During 1920, tenders were called for electrification of the tunnel, a coal-fired power house, & 6 electric locomotives

1921: "EO" class electric locomotive, no 3, was constructed at the English Electric Company's Dick Kerr Works, Preston

28 Dec 1922: Coal-fired power station built at Ōtira & water piped from a reservoir built c.625 feet above in hills

The power station had two turbine-driven generators of 1,600 kilowatts capacity

15 Feb 1923: Electric locomotives assembled at Addington Workshops, Christchurch for travelling through the Ōtira Tunnel

1 Aug 1923: Overhead electrical wires outside the Ōtira Tunnel

c.1923: Overhead electric wires at the Ōtira Railway Station

A crowd gathers to celebrate the opening of the Ōtira railway tunnel

Crowd includes Sir Joseph Ward (2nd from left) & PM William Massey (centre) & Min. of Works Gordon Coates (holding coat)

Crowd from Westport at the opening ceremony

c.1923: First wagon of timber for John Jackson & Co Ltd through the Ōtira tunnel

A train enters the Ōtira tunnel in the Southern Alps in winter, shortly after the tunnel was completed

From 1923, electric locomotives used were the EO class, then from 1968 the EA class

1923: "E" 1, E class battery-electric locomotive built by Dick Kerr & Co. in 1921

c.1928: Machinery at the electricity generation plant

1931: "EO" 3, an EO class electric locomotive

1 Feb 1933: A train-load of motorcars belonging to tourists photographed at Ōtira after passing through the tunnel

20 Oct 1937: Two of the new lattice towers that carry the transmission line from Lake Coleridge to the West Coast

In 1939, six KB steam locomotives, especially constructed for heavy loads, began operating from Springfield

The KB steam locomotives were built in Dunedin & were used to haul both goods & passenger trains

KBs stopped hauling passengers in 1959 when diesel railcars introduced, & last KB locomotive was retired in 1969

In 1941, the electric power house at Ōtira was replaced by power supplied from the Lake Coleridge hydro power station

In 1987, the TranzAlpine Express began between Christchurch & Greymouth. (Photo: DXC 5520 at Greymouth, 1 April 2010)

TranzAlpine train journey takes 4.5 hours

During 1988 & 1991, trials held using diesel-electric DX class locomotives instead of electric locomotives

In 1997, electrification replaced by using DX locomotives with new air intakes & extraction fans in tunnel

After a train enters the tunnel from the Ōtira end the door closes off the entrance, & a large fan extracts the fumes

2010: JB 1236 (restored ex NZR steam locomotive) passenger train arriving at Ōtira before heading through tunnel