Changes to the Railway Line through Porirua City

This page outlines the subsequent realignment, electrification and track duplication of the railway line through Porirua City.

Change of ownership from private to public

In 1908 the Government exercised its option and bought the line from the W&MRC. The line then became an important part of the North Island Main Trunk Line (NIMT) between Wellington and Auckland. As the areas north of Wellington developed, it also became a significant part of the Wellington region’s northern suburban rail network.

Avoiding the bends - the Tawa Flat deviation

The first major change to the line was the Tawa Flat deviation, opened for goods trains on 24 July 1935 and to passenger trains two years later. This project included decommissioning the Belmont Viaduct and the construction of two major tunnels between Wellington and Tawa to ease the gradient of the line through this area, improving the carrying capacity and shortening the travelling time from Wellington to Paekakariki and beyond.

Electrification of the suburban services

The second major change was the electrification of the line. First mooted as early as the opening of the Otira section in the South Island in 1923, it was not until 1933 that it was agreed to electrify the line from Wellington to Paekakariki as part of the Tawa Flat deviation project; initial work on this began in 1934 and was completed by 1940.

The electrification and duplication of the lines necessitated major changes to the railway stations over the next twenty years. New stations were constructed which were accessed by subways and/or footbridges. The first of the new stations and subways was constructed at Plimmerton in 1940; a new station was put up at Pukerua Bay in 1941, later followed by Paremata and Porirua in the late 1950s, while new suburban stations were added at Mana (1949), Muri (1952) and Kenepuru 1963.

Double-tracking of the line

Image showing workers preparing for laying of second railway track north of Plimmerton, late 1930s.
Preparation for laying of second railway track north of Plimmerton, late 1930s.
Pataka Museum CD 16 Film 62 C.3.5.

Duplication of the rail line through Porirua City began in 1940 with the section between Plimmerton and South Junction (near Muri Station at the top of the Paekakariki Hill) and from the North Junction at the bottom of the Paekakariki Hill. Automatic signaling along the track from Tawa Flat to Paekakariki was also introduced at this time. Work on duplicating the rest of the line was delayed during the Second World War and the final section was not completed until 16 October 1961.

The rail line was electrified through to Paekakariki by June 1940 and an intensive suburban commuter service introduced, first operating as an electric-hauled service, before electric multiple units were introduced in 1949. The main commuter service continues to run with electric units today (using the Ganz Mavag EMUs introduced in 1979, soon to be upgraded to the new Matangi units).

As part of the duplication process it was decided to realign the track from Porirua to Plimmerton on the eastern side of Porirua Harbour. While the original line followed the natural curves of the bays around the harbour it was decided to construct an embankment and causeway across the harbour. According to Hoy, “…the new alignment was two miles long with a width of 36’ at the top and approximately 104’ at the base. The spoil came from Mungavins Point, Porirua." [See Ref. iv]

The work was undertaken by the Ministry of Works (formerly the Public Works Department) and was associated with a programme of other significant civil works that was carried out at the time, including the development of the motorway and diversion of the Porirua Stream. [See Ref. v]

The new rail alignment and duplication also required the construction of a new rail bridge at Paremata (on the west side of the original bridge).

The Minister of Railways formally opened the Porirua to Mana duplication on 7 November 1960. The final section between Mana and Plimmerton was opened on 16 October 1961. The delay in finishing this section off was, according to Hoy (p. 72), necessitated by the rebuilding of two small bridges near the entrance to Plimmerton Station.

Over the years there have been a number of accidents and incidents, including fatalities on the line both during its construction and once the line became operative. The earliest fatal accident on the line was on Christmas Day 1895, when a young girl fell under a train at Paremata Station. [See Ref. vi]

In 1896, engine No. 13 was engulfed by a slip as it came out of tunnel 13 and pushed down to the beach below, luckily without serious injury to driver or fireman.

The most difficult section of the line is between the tunnels on the Paekakariki Hill. Over the years there have been a number of rockfalls and following a derailment on 19 September 1961 caused by a rockfall over the abandoned No. 12 tunnel “…a timber and mesh fence was erected under the line of the slip and the railway moved a few feet closer to the edge of the cliff to allow a dropping face for any further rockfall.” [See Ref. vii]

Changes to the rails and sleepers have been made over the years as well as lowering the floor levels in the tunnels to cater for increases in the dimensions of rolling stock.

References

iv Hoy, Douglas George. West of the Tararuas - An illustrated history of the Wellington Manawatu Railway Co. Wellington : Southern Press 1972 p. 70
v Pierre, Bill. North Island Main Trunk Wellington, 1981
vi ACCIDENTS & FATALITIES. A YOUNG GIRL KILLED ON THE RAILWAY. Evening Post, Volume L, Issue 152, 27 December 1895, Page 2 from Papers Past
vii Hoy, Douglas George. West of the Tararuas - An illustrated history of the Wellington Manawatu Railway Co. Wellington : Southern Press 1972 p. 72

Return to the 'Porirua's Rail Heritage' page or continue on to the 'Railway Tunnels in Porirua' page