Kapiti Line


Metlink's Kapiti Line is the electrified southern portion of the North Island Main Trunk railway between New Zealand's capital city, Wellington, and Waikanae on the Kapiti Coast, operated by Transdev Wellington on behalf of Greater Wellington Regional Council. Trains run frequently every day, with stops at 16 stations. Until 2011 it was known as the Paraparaumu Line.

Construction

The Kapiti Line was constructed by the Wellington and Manawatu Railway Company as part of its line between Wellington and Longburn, south of Palmerston North. It was built by a group of Wellington businessmen frustrated with the indecision of the government about the construction of a west coast route out of Wellington.
Construction of the line began in September 1882 and followed a circuitous, steep route via Johnsonville. It was opened to Plimmerton in October 1885 and completed on 3 November 1886. The final spike was driven just north of Paraparaumu, at Otaihanga.
The government acquired the Wellington and Manawatu Railway Company on the 7 December 1908 and incorporated it into its national network as the southern portion of the North Island Main Trunk line.

Deviation and electrification

In 1928, work began on a deviation to avoid the difficult section of the line between Wellington and Tawa through Johnsonville. The deviation required the construction of two significant tunnels between Kaiwharawhara and Tawa. It opened as a single track line to freight on 24 July 1935 and as a double track line to passengers on 19 June 1937. The Wellington to Johnsonville section was retained as the Johnsonville Line.
Electrification from Wellington to Paekakariki was completed on 24 July 1940, avoiding the smoke nuisance in the new deviation's lengthy second tunnel, and providing extra tractive effort on the Paekakariki Hill between Pukerua Bay and Paekakariki. Paekakariki became a major station where long-distance trains swapped from steam to electric motive power and became the northern terminus of the commuter line for many years. Electrification was extended to Paraparaumu on 7 May 1983 and to Waikanae on 20 February 2011.

Duplication

The Manawatu Railway Company railway when first constructed was a single track railway with crossing loops at principal stations to allow opposing trains to pass. In the 1920s the need for extra train services on the line was recognised, both to increase the tonnage of goods trains and to allow more frequent suburban passenger services. To increase the number of trains that the line could carry, duplication and electrification of the line along with other improvements, such as curve easements, was planned and progressed in stages.
The first section of track duplicated was the Tawa Flat deviation. Completed in 1935, it provided double track from Wellington to Tawa Flat, and bypasses the steep 1 in 36 grades from Wellington to Ngaio on the Johnsonville Line.
The section from Plimmerton to South Junction and from North Junction to Paekakariki was completed in 1940. The difficult single track section along the coast between South and North Junctions which passed through five short single track tunnels remaines as single track.
As part of the Plimmerton to Paekakariki duplication, a Westinghouse three-wire Centralised Train Control system was installed in 1940; to control trains from Wellington. It was the first CTC system in New Zealand and the first outside the United States of America. This avoided the need for two new signal boxes at the North and South junctions and the need with "tablet" working to continuously man five stations ; so requiring 19 men for traffic working. CTC working applied between Paekakariki and Plimmerton on 25 February, Plimmerton and Paremata on 30 June and Tawa to Porirua on 4 December 1940; giving full traffic control from Wellington to Paekakariki.
From 14 June 1943 a siding for the US Marines' camp at McKays Crossing with a crossing loop and tablet station was opened; near where the Wellington Tramway Museum is now located. With duplication of the track from Paekakariki to McKays Crossing and automatic signalling from Paekakariki to Paraparaumu, McKays Crossing was relay worked from the Paekakariki South signal box from December 1943. But on 25 March 1946 the catch points and two cross-overs of the siding were lifted, and McKays Crossing became the point where the double-track section north ended.
Further duplication was delayed in the 1940s but continued in the 1950s with the completion of the Tawa to Porirua section on 15 December 1957.
Double track from Porirua to Mana was opened on 7 November 1960. Harbour reclamation allowed mostly straight track with the line no longer following the curves of the shoreline bays north of Porirua. A new station and bridge at Paremata were required. The Mana to Plimmerton section was opened on 16 October 1961.
In conjunction with the extension of electrification to Paraparaumu in March 1983, double track was extended from Paekakariki to McKays Crossing on 5 December 1993. The section between McKays Crossing and Paraparaumu, built across a peat swamp, remained single track. Extension of double track from McKays Crossing to a junction south of the Waikanae River bridge was completed in February 2011 to coincide with the extension of electrification to Waikanae.

Operation

From electrification in 1940 until the 1980s, the majority of commuter services on the line were operated by DM/D electric multiple units, with some carriage trains hauled by ED and EW electric locomotives, particularly at peak periods. ED and EW locomotives also hauled freight trains over this section until the tunnels between Pukerua Bay and Paekakariki were lowered in 1967 and DA diesel locomotives could be used into Wellington.
From 1982, the new EM/ET electric multiple units were delivered. They had been ordered to replace the wooden carriage trains hauled by electric locomotives on commuter services and largely displaced the DM/D units on the Paraparaumu Line.
By the 1980s, the ED and EW electric locomotives were not required for either freight trains or for commuter trains. They were retired due to age and lack of use, the EDs by 1981 and the EWs by 1988. From 2010 the introduction of the Matangi EMUs provided extra passenger capacity, and enabled the remaining DM/D EMUs to be withdrawn in 2012. A second batch of Matangi EMUs was then ordered to replace the EM/ET EMUs.
A proposal to extend the electrification to Waikanae was approved by the Greater Wellington Regional Council on 8 May 2007. This project included the double tracking of the single track line between MacKays Crossing as far as the rail underbridge and river bridge south of Waikanae. The $90 million project started in December 2008, and was completed in 2011, with the first commuter trains to Waikanae on 20 February. Completion of the project was delayed to 2011 to minimise commuter disruption by working in the quiet end-of-year holiday period, according to ONTRACK program director David Gordon. The project involved 50 workers and 20 machines installing 600 traction poles in eight or nine metre deep holes, and laying 30 km of rail and 30,000 sleepers. The project allows commuter services from Waikanae every 15 minutes at peak travel times but more commonly every 30 minutes. The new Matangi electric multiple units were used on the Kapiti Line from mid-2011. Paraparaumu and Waikanae stations were upgraded at a cost of more than $1 million each. Upgrading Waikanae station rather than moving it south of Elizabeth Street or providing a road underpass was criticised locally, as frequent closing of the Elizabeth Street level crossing south of the station could increase traffic congestion in Waikanae. However this has since been alleviated by the opening of the Kapiti Expressway which has moved the main road west and out of the centre of Waikanae itself.
Ten traction substations along the line take electricity from Wellington Electricity or Electra's 11,000-volt distribution network and transform and rectify it to 1500-volt direct current for the overhead traction lines. The substations are located at Wellington, Kaiwharawhara, Glenside, Paremata, Mana, Pukerua Bay, Paekakariki, Raumati, Lindale and Waikanae. Also along the line are two "cross-tie" substations at Ngauranga and Tawa, which provide a switching function but don't have transformers or rectifiers.
Public road-rail crossings have warning lights and barriers, and some are now fitted with automatically locking pedestrian gates to prevent use while alarms are operating.

The future

Proposals for new stations at Raumati South, between MacKays Crossing and Paraparaumu, and Lindale, north of Paraparaumu near Otaihanga, were on hold, to be reconsidered after 2010, as it was claimed that there were problems affecting a station at Raumati and an unstable hillside behind the line.
The 2013 Review and Draft 2014 Review of the Wellington Regional Public Transport Plan confirmed that building additional stations on the Kapiti Line at Raumati and Lindale was no longer recommended, with the cost of new stations outweighing the benefits. The detailed analysis for Raumati said that the modelled peak-hour patronage needed to be about 300 new passengers to justify a new station, and that most Raumati users would have switched from Paraparaumu Station. Network extensions beyond the current Metlink rail operation limits would be by "shuttles or non-electrified services" running to Wellington.
Proposed infrastructure upgrades include sleeper replacement in tunnels, stabilisation of high-risk slopes and renewal of one bridge with timber elements. To cater for freight trains with more frequent passenger trains, there will be a new freight loop at Plimmerton or an improved loop at Porirua ; and Plimmerton will get a high capacity train turn-back facility as a terminal station. Power supply upgrades will allow more long trains.
The single-track section above the coast between Pukerua Bay and Paekakariki may also be double tracked through a single long double track tunnel or replaced by a less steep deviation; although the present proposal is to daylight only the northernmost tunnel which is through rock, and have double track north from there.

Extension to Ōtaki

Further extension of the electrification north from Waikanae to Ōtaki remains a possibility. A group known as "Save Kapiti" is actively campaigning for the extension. The Otaki Community Board also supports the extension of electrification. Provision has been made during road earthworks north of Waikanae for a future crossing loop between Peka Peka and Ōtaki. In 2012 the Greater Wellington Regional Council investigated extension of the electrification with Matangi trains north of Waikanae to Ōtaki and north of Upper Hutt to a new station at Timberlea.
In March 2014, the GWRC said that electrification to Ōtaki was estimated to cost $115 million to $135 million and was too costly for the number of new passengers it would attract. Because the trip would take over an hour, new trains with toilets would be required. As an alternative to electrification, it was suggested that diesel multiple units could be used on services north of Waikanae. This could be a "final nail in the coffin" for the under threat Capital Connection service from Wellington to Palmerston North, which also stops at Ōtaki. During the 2017 general election, the Green Party proposed extending electrification to Ōtaki as an alternative to the Northern Corridor extension from Pekapeka.
In the lead up to the local authority elections of 2019, candidate for Mayor of the Kapiti Coast District, Gwynn Compton, started a petition to extend electrification to Ōtaki.