Centennial Highway, State Highway 1 (Ngauranga Gorge to Paekakariki)
Engineering Work (eg road, bridge, sawmill, dam)
The Centennial Highway follows some of its original route from Ngauranga Gorge through to Paekakariki. Newer sections include the motorway which now bypasses Tawa township. The section between Paremata and Paekakariki was an important and demanding project for the Public Works Department during the 1930s. It offered many significant challenges for engineers and builders alike. It was constructed on a wide variety of land forms - sand dunes through Paremata, swamp land through Plimmerton, carved-out hillsides at Pukerua Bay and required extensive sea-walling along the coastal strip between Pukerua Bay and Paekakariki.
The engineers for the project included J. Wood CMG MICE Engineer in Chief, H. Watkinson AMICE District Engineer and H. L. Hume AMICE Engineer in Charge. The road was designed and constructed to the highest standards of the day, with correct cambers [transverse arch of the surface of the road] for speed (superseding the previous use of high-crown roads where most bends were off-camber and intrinsically dangerous for motor vehicles) and wide sweeping bends to promote good visibility along the entire road.
The section of the road, from Pukerua Bay to Paekakariki, has changed little since the road was constructed and remains on the original alignment (although the road is now somewhat wider than when it was built). The entire extent of the original massive concrete sea-walling remains along this length of the road. The remainder of the road from Plimmerton to Pukerua Bay has been much modified over the years (much of it to four-lane highway on new alignments and gradients).
Features of particular interest along the road include the close alignment with the Wellington-Manawatu railway line, cuttings, the passage past the Taupo Swamp, the remnants of coastal defences emplaced in the Second World War, the commemorative marker at Pukerua Bay and the sea-wall.
The 1940 Centennial, planned for five years and publicly funded, was a deliberate act of national self-definition by the first Labour government. The Centennial was not to be just a series of one-off events, but rather it was about re-kindling the New Zealand Pioneer and the spirit of progress. The government undertook a large number of public works projects that required manual labour such as road building, which reflected both this early pioneer spirit and progress.
While not initially conceived as monuments, in Wellington, the Ngauranga Gorge, Hutt Road, and in particular Coastal Road developments, were rebranded as symbols of progress. At the opening of the Coastal Road in November 1939, much was made of the fact it had been constructed alongside the pre-1848 coastal route. "How few will realise or ever know as they speed in comfort along the new road of the difficult journeys made by our early mailmen and travellers on foot along this same path and difficulties they encountered', the Evening Post trumpeted" ("The Centennial and Progress - New Zealand Centennial, 1940", from New Zealand History On-Line).
The objective of the new highway was to replace the Paekakariki Hill Road as the main route between Wellington and Paekakariki. The Paekakariki Hill Road largely followed the route of a military road built on the line of a Maori track in the 1840s and was not suitable for modification to suitable standards for "modern" (i.e. motorised) traffic; an alternative route had long been considered once the demands of that motor traffic began to be understood.
The construction of the road section between Paremata and Paekakariki commenced, in late September 1936, shortly before the opening of the Paremata Bridge on 3 October 1936.
The Paremata Bridge eliminated the traverse around the Pauatahanui Inlet to get from Paremata to Plimmerton cutting some miles from the journey distance here. There was a proposal at the time to operate a toll on the bridge but it is unclear as to whether this ever proceeded
The new coastal road along with the Ngauranga Gorge Road was officially opened on 4 November 1939. This event was contempory with the Centennial Exhibition at Rongotai which opened four days later on 8 November 1939 and the road has been referred to as Centennial Highway ever since.
While that title is most commonly taken to be the section of coastal road between Pukerua Bay and Paekakariki, the Centennial Highway is actually the whole length of road from Ngauranga Gorge (via the main road through Tawa township) to the southern-most end of Paekakariki. Although the road was opened at the requisite time to serve the purposes of the Centennial, it was not completely tar-sealed and fully accessible to the public until Christmas Eve 1939 (Dallas, 1998).
The coast road was described by the Minister of Public Works, Hon. R. (Bob) Semple, as the most notable major road work of the (Centennial) year. It cut over four miles off the old route, its highest point was 290 feet compared 815 feet on the old route and the gradient was also more or less halved from one in nine to one in seventeen on the average. It cost £350,000 for nine miles of road including the Paekakariki seawall. Semple was quoted as saying at the time that people had forecast that the Government would empty the Treasury into the Tasman before it was finished. In fact the job was finished twelve months ahead of schedule and had come in under cost.
A memorial stone cairn (and fountain) and a commemorative plaque were constructed in one of the lay-bys along the Paekakariki seawall and were unveiled at the opening; this can still be seen today.
While many of the workers on the road came from the local area, public works camps were also set up including one at Plimmerton on the eastern side of the railway line before the township and the one at up at Tawa (Taua) Tapu near Airlie Road. These workers were responsible for the construction of the road alongside the Taupo Swamp, through Pukerua Bay and along the coast to Paekakariki including the construction of the one mile long coastal seawall. The workers faced two major challenges, firstly digging down to 20 feet to find solid ground next to the Taupo Swamp and secondly working night and day on the coast to construct the seawall then back filling it to create a platform for the road. This challenging work took three years to complete.
State Highway 1, Ngauranga Gorge to Paekakariki
Wellington / Kapiti
In the Ngauranga Gorge section the alignment of current 6 lane divided SH1 matches the 1939 alignment of the 4 lane divided "Centennial Highway", which was a radical relocation, made possible by developments in construction machinery. Detailed record is now mainly photographic and written.
Nature of Engineering
Infrastructure (incl. Road, water, ports)
(Click image to enlarge )
(Click image to enlarge )