North–South Junction
The line is on an unstable hillside, the Paekakariki Escarpment, and with a two-lane section of State Highway 59 (formerly State Highway 1; to 7 December 2021) below, which runs along the edge of the sea front, the route is almost perpendicular in places and the section constitutes a bottleneck for rail transport north of Wellington.
[1] The line has steep gradients south from Paekakariki and climbing to Pukerua Bay at a ratio of 1 in 66, with short sections of 1 in 60 and 1 in 118.
Construction of the southern section of the line was supervised by James Fulton, under Harry Higginson the chief engineer of the WMR.
[4][1] Access was a problem; Brown built a temporary tramway along the beach from Pukerua Bay to just below No 13 tunnel on the wavecut platform at the cliff base.
A saddle-tank works locomotive “Belmont” plus two wagons and a van were lowered from above to the beach; they were also used for passengers and light goods.
The WMR chairman J E Nathan arranged a special train from Wellington with 120 passengers, and held a “laying the last brick” ceremony with a plaque in No 12 tunnel.
[7] 1967; track in the tunnels was lowered, so that freight trains with DA class diesel locomotives could run through to Wellington without an engine change to an electric loco at Paekakariki.
2011 (February); duplication (double-track) extended from Mackays Crossing to past Pukerua Bay and the beginning of the Paekakariki Escarpment section.
[9] A short section of sharply-curved track north of Muri on the North–South Junction and the Tawa No 2 Tunnel are the only sections of the Wellington overhead power catenary system where for technical reasons a modern auto-tensioned overhead system could not be installed; the Hutt Valley Line and the Johnsonville Line were also upgraded in 2018-2021.
[15] On 17 August 2021 a landslip blocked the Kapiti Line one kilometre south of the Fisherman’s Table restaurant at the north end of the single-line section, and derailed a Matangi train.
[16][17][18] 1989, 19 November - a three-coach southbound EMU derails after running into slip, north of Bean Pole Fence, on the single track section between Pukerua Bay & Paekakariki;[19] 1979, October - Muri railway station; Signal 3132 at Muri was over-run by a diesel-hauled goods train (diesel locos was not fitted with trips) and was involved in a minor rear-end collision with an EMU commuter train; one of two commuter trains ahead.
[21] 1961, 19 September - between Pukerua Bay and Paekakariki, EW No 1806 hauling a freight train was derailed by a fall of rock over the abandoned No 12 tunnel, just after the passing of the Auckland Express.
EW 1806 was nearly pushed over the bank to the road below, and was subsequently given an "A" grade overhaul; the first given to the class in ten years of service.
The WMR carriages were higher the NZR loading gauge at 12' 2½" (3.72m) rather than 11' 6" (3.51m), and were required to be tested before running on Government lines.
[25] 1896, 23 June - outside No 13 tunnel engine No 13 hit a rock slip, and toppled down the embankment to the beach 25 ft below, taking with it four wagons of timber.
[33] Double-tracking has been urged by the Greater Wellington Regional Council, which is keen to improve the speed and frequency of suburban commuter services.
