One of the earliest wind turbines to be built in New Zealand was the Brooklyn turbine in Wellington.  Built in March 1993 as part of a research project, it has a maximum energy output of 225kW – enough to supply about 70 homes throughout the year.  Newer turbine designs have about ten-times the capacity of this early model.

Te Apiti Wind Farm, Saddle Road

There are several wind farms around the Manawatu Gorge in the central North Island.  At Te Apiti, north of the Gorge, the turbines are readily accessible to the public, and provide a surreal landscape to drive through.  Te Apiti is Meridian Energy’s first New Zealand wind farm to supply electricity into the national grid.  It was built over 12 months in 2003-2004, including construction of 10-metre wide roads to provide access for the 400-tonne crawler crane used for turbine installation.

Each of the 55 turbines produces 1.65Mw, enough power for up to 900 average homes.  The turbines were manufactured in Denmark, the blades in the Isle of Wight, and the towers in Vietnam and Australia.

The turbines at Te Apiti are a three-bladed design.  South of the Gorge, however, some of the many turbines now in operation across the ranges – at a number of independently-run wind farms- are locally designed and built two-bladed turbines.  These have been developed by New Zealand company Windflow Technology.  Three-bladed turbines are more straightforward to balance, but two-bladed designs provide other advantages – including cost efficiencies in term of the quantities of materials required to construct them, and also in terms of the fuel costs associated with transporting the turbine components onto site.  In addition, two-bladed designs need smaller towers than three-bladed designs, which makes two-bladed turbines a preferred option in difficult-to-access terrain. 

How do wind turbines work?

Perhaps surprisingly, wind is a type of solar energy.  Wind happens because the Earth’s atmosphere is heated unevenly by the sun – because of the bumpiness of the Earth’s surface, and because of the Earth’s rotation.

Wind turbines work in the opposite way to an electric fan – the wind turns the turbine blades, which spin an internal shaft, which connects to a generator, which generates electricity.  Most often the internal shaft is set horizontally, as in the turbines you see around the Manawatu Gorge area.  Sometimes, however, the shaft is set vertically; these are called Darrieus (or ‘egg beater’) turbines, after their French inventor.

Turbine cross-section

Horizontal-axis machines were traditionally used in the Netherlands and Crete.  The vertical-axis style also dates back many centuries, notably in China and Pakistan.

The horizontal-axis turbine is used most often because it is a considerably more efficient generator than the vertical-axis design.  The vertical, Darrieus-type turbine generally requires an additional starting device at low wind speeds, and is difficult to stop from over-speeding (spinning too fast).  The main advantages of the vertical-axis design are that it is simple and inexpensive to construct, and that it can receive wind from any direction.

Modern turbines typically have only two or three blades, aerodynamically designed for maximum strength and efficiency.  One challenge is to ensure they can cope with wind gusts – often achieved by ‘feathering’ the blades or turning the entire turbine head so it stops operating until the wind eases.

When a wind farm is constructed, the turbines are trucked to the site in sections and then put together on-site.  Usually, the turbine tower arrives in several sections, the nacelle (which sits at the top of the tower and houses all the generating components) comes as one section, and the turbine blades, rotor, hub and nose cone arrive in separate pieces.  The towers are typically tubular steel, and the blades are typically carbon fibre of fibreglass.

The exciting thing about wind energy is that it is a renewable energy resource.  In the right location, it won’t ‘run out’, as, say a gas energy resource will eventually.

Turbines do produce noise, but are designed to comply with the acoustics standard NZS 6808, which says the noise at a property boundary must not exceed 40dB, or background noise plus 5dB.  By comparison, people whispering is 30dB, and refrigerators are about 43dB.

In New Zealand, you will also see wind farms at many other locations around the country, including the Makara Wind Farm near Wellington.  We are fortunate to have one of the best wind energy resources in the world.

© Karen Wrigglesworth and Geeky Getaways, 2011.

Construction of Wynyard wharf commenced in 1845, and was completed by 1851.  It barely reached low water mark, but because it had water laid on (via a wooden flume from a spring in Eden Crescent), it was a popular layover for ships.  By comparison, the wharf at Queen Street was not started until 1852. 

Wynyard Wharf in the late 1800s. From 'Early NZ Engineers' by Furkert.

Reclamation of the area now known as the Wynyard Quarter was progressed between 1886 and 1901, based on a comprehensive plan for harbour development put together by Engineer-in-Chief John Caruthers (1836-1914), who was appointed to the role in 1871.

Within the Wynyard Quarter, two silo features have been retained in recognition of the area’s importance as part of the industrial heritage of Auckland.  Now named Silo Park, the area incorporates the disused 35m high Golden Bay Cement Silo 7 and the nearby ‘six pack’ silo cluster.

Silo Park under construction. The 'six-pack' (left) and tower silo (right).

The first upright agricultural silo – made from wood on a rock foundation – was invented and built in Illinois, USA by Fred Hatch in 1873.

The world’s first tower storage silo – designed as a cylinder to overcome the problem of silage going mouldy in the corners of storage bins – was invented by agricultural scientist Franklin Hiram King from Wisconsin, USA (1848-1911).

Base of one of the 'six-pack' silos.

Silos are a common sight in many parts of the world, and are used as an efficient and space-saving way to store large quantities of dry material under cover.  Uses range from bulk storage of grain, silage (basically pickled grass, used as an animal feed) cement, coal, sugar, food products, and sawdust.  With cement, it is essential that the product is kept dry until it is used, as contact with water – even just moisture in the air – will cause it to deteriorate and lose its strength and binding capacity.

The cement silos at the Wynyard Quarter are called tower silos for obvious reasons.  Other types of silos in widespread use include horizontal bunker silos, and bag silos (typically one-use systems made from plastic).  Still other silos are used for defense purposes to store and launch missiles.

Base of 'six-pack' silos showing loading hoses.

The cement silos at Silo Park in Auckland were constructed alongside the harbour for easy access to ships and barges.  A rail line also ran nearby.  Using a silo for harbourside storage meant there was less urgency when large quantities of cement were unloaded but could not immediately be transported further afield.  It also enabled the cement to retain its quality irrespective of the weather, and significantly reduced loss of product due to spoiling from exposure to rain or air.  

The ‘six-pack’ cement silo at Silo Park was built in the 1960s, and was used to store up to 7200 tonne of dry cement before it was transported to warehouses and suppliers throughout the city.

Base of the Golden Bay cement silo tower at SIlo Park.

Silos are round because they are able to be more easily filled and emptied due to a lack of corners where the stored material can become stuck.  The cylindrical design also ensures that stored materials are cycled so that older stock is not inadvertently retained, potentially aging newer supplies. 

Loading and unloading of silos like the ones at Silo Park is typically done using a large fan called a silo blower, which helps to efficiently fill the silo and later to expel the cement into a waiting truck or rail wagon.

Since the 1970s, many silos have been built to an ‘inverted cone’ design, with an upward-pointing 60° cone inside the silo, which forces the stored product to discharge from around the perimeter of the silo wall.

View of the Sky Tower from SIlo Park.

Silos are designed specifically for the type of cement they will hold, which includes considering the potential weight of the material pushing against the walls of the silo, and the chemical nature of the product and the silo walls.  Silos are labelled with the type of cement they are designed to hold – some silo construction materials have the potential to react with the various components in some cement blends, causing premature deterioration of the product.

Modern silos also typically incorporate a weighing system to enable the amount of stored product that is released, and the amount remaining in storage.

As part of the development of Silo Park, the silo tower and ‘six-pack’ can be climbed for harbour views, and there are also plans to screen outdoor movies at the park in the summer months.

Makatote Viaduct

Glasgow-born engineer Peter Seton Hay (1852-1907) designed many of the bridges along the North Island Main Trunk Line route, including the viaducts at Makatote, Makohine, Mangaweka and Taonui.  He was also interested in the potential for the development of hydro-electric power generation in New Zealand, and produced an extensive report on this subject in 1903.  Hay is, however, best remembered for his work on overcoming the problem of how best to develop a rail route over the Southern Alps in the South Island.  Hay was educated in Dunedin, and became the first BA graduate of Otago University in 1877.  He was subsequently awarded a Master of Arts degree in mathematics with first class honours.

All of the viaducts in the central North Island area were designed to the classic North American steel trestle pattern.  They incorporate a series of open-work steel towers supporting Pratt trusses up to 30 metres each.

The highway passes under the viaduct on the south side of the valley.

The first of the central North Island viaducts to be completed was the Makohine Viaduct near Mangaweka, in 1902 (it was started in 1896).  This large structure spans a gully some 76 metres deep.  By comparison, however, the Mangaweka Viaduct (now demolished) stood an impressive 289 metres above the Mangaweka Stream.  It was completed in 1903, only 12 months after work commenced.

The Makatote Viaduct, which spans a gully 79 metres deep and is 262 metres in length, was started in 1905 and completed in July 1908.  It is now the highest of the viaducts on the North Island Main Trunk Line.  This viaduct was built by a company called J & A Anderson Ltd, of Christchurch, who despite their best efforts had to endure considerable delays due to machinery failures, cement shortages, floods and foul weather before the structure could be completed.  Because of the difficulty of transporting materials to the relatively remote site, the company established a modern workshop on site where they could manufacture most of the steel components themselves.  This workshop was powered by a wood-burning boiler and steam engine, and was lit by electricity.  A water turbine drove a stone crusher and concrete mixer, and an electrically-driven cableway assissted with access to the viaduct as it was constructed.

The IPENZ plaque.

The Makatote Viaduct was built to carry 84-tonne locomotives, but by the late 1920s all bridge and viaducts along the Main Trunk Line needed to be substantially strengthened to enable them to carry the new design locomotives, which were up to 140 tonnes with a maximum axleload of 14 tonnes.

A subsequent project was carried out during the 1980s to further modify the viaducts to enable them to carry the 18 tonne and higher tractive forces of the electric locomotives introduced as part of the electrification of the Main Trunk Line.  Concrete electrification masts were also installed. 

Makatote Viaduct showing the 2008 foundation unerpinning work.

The most recent project on the Makatote Viaduct was completed as recently as 2008.  This involved the underpinning of one foundation with deeper foundations to protect the structure from scour of the stream bed.

The Makatote Viaduct has a Category I Historic Places Trust classification.

The Bastia Hill tower was built in the 1920s to supply water to the newly-developing suburbs of Bastia and Durie Hills.  Because of its height, the provision of drinking and fire fighting water for the Garden Suburb (Durie Hill) was a  significant problem.  Subdivision began in 1919, but settlement was slow.  By early 1923 a council report tells of streets badly overgrown with weeds and damaged by stock.  It was hoped that an improved water supply would increase the Garden Suburb’s attractiveness for settlement.

Bastia Hill tower

By putting a large (546,000 litre) water tank on a tower on Bastia Hill, engineers were able to obtain enought head for both suburbs to receive a high pressure water supply.  Bastia Hill tower stands higher that the War Memorial tower on Durie Hill.  The height of the bottom of the Bastia tank is 55m above the highest part of Durie Hill, giving 530kPa static pressure.

Bastia Hill tower was designed by City Engineer Crofton Staveley and Principal Assistant Engineer A Gumbley, and built by around 16 council staff at a cost of £22,900.  It was designed to reflect the arched aqueducts and towers of the water supply networks of ancient Rome.  In June 1925, Georgetti Rd was gravelled in preparation for the carting of heavy material to the site.  Construction began late-1925, and by mid-April 1927 the tower had reached a height of 37m (already above the full height of the Durie Hill tower) – to the water-tank floor level.  Final height, including the dome, is 50m.  The weight of the tank when full is over 2000 tonnes.

On 23 April 1927, the Wanganui Chronicle devoted almost a full column to a reporter’s visit the previous day.  “It was to this dizzy height [the uppermost balcony level] that a Chronicle man climbed yesterday afternoon.” Would they be so fearless today?!

The water tank and telecommunications paraphernalia, including the Christmas Star/Cross which is lit at night and can be seen thoughout much of the city.

The tower is constructed from reinforced concrete with rolled steel rods providing the main reinforcement to the nine vertical columns.  Massive, well-spread foundations were constructed to support the tower’s considerable weight.  Making the foundations wide ensures a more moderate unit pressure is achieved across the tower’s base, improving both strength and stability.  The base is a solid mat of steel rods 32 tonnes in weight, embedded in 5500m²  of concrete (all mixed and poured on site).

The three floors are not only for access.  They also hold the outer columns from bowing outwards under the water’s weight.  Curved struts and stanchions (upright bars) provide additional flexural (bowing) strength.  Below the tank and at the first landing, arched curtain walls (vertical concrete panels) increase stability.  The tank floor is supported by radial beams (like wheel spokes) resting on girders set between the outer columns.  The girder ends support the balcony encircling the tank, and carry columns that support the cornice (crown) and dome.

The spiral staircase is cantelevered (supported at one end like a diving board) from the central column, which also houses the overflow (downward) pipe from the tank.  The main feed pipes rise beside the outer edge.  The dome was assembled on the ground and then fitted into position via an electric hoist.

The elegant spiral staircase cantelevers off the tower's central column

The tank is supplied with an automatic electric pump station, drawing water from town supply.  The dome protects the water from the sun, and also prevents eccentric loading (wobbling) of the tower’s secondary columns (say from wind gusts creating waves).

Concrete was mixed on site and carried aloft in an electric lift.  Wooden scaffolding supported the concrete until it cured.  Only the large curved girders used for the arc in the diameter of the tank were transported by motor lorry.  According to one engineer, “the work of [girder] transportation was altogether a rather ticklish job”.  There was an on site blacksmith shop where iron reinforcing bending was done, plus an up-to-date concrete mixing plant, electric hoist, band saw, and electric drills.

Problems arose from the unexpectedly strong winds experienced once the tower had risen a short height.  Long reinforcing rods couldn’t be used due to the wind pressure, meaning only short lengths were used which didn’t rise above the boxing.

The water tower received a thorough maintenance checkup and concrete refurbishment in the 1990s, and is still providing water to the Garden Suburb over ninety years after it was built.  She’s quite the elegant Twenties dame, even now.

Sources: Council archives, Whanganui Regional Museum, Alexander Heritage Library.

© Karen Wrigglesworth and Geeky Getaways, 2011.

The present aviary was officially opened on August 12, 1979, along with the dovecote which stands nearby.  The concept of a free-flight design, which allows visitors up-close walk-through access to the birds, was a novel idea in the late 1970s.

The Wanganui aviary proposal is attributed largely to Barrie Harvey of the Round Table.  Considerable effort was made to come up with a suitable, workable design solution, and even then the aviary was not straightforward to construct.  Built largely as a volunteer project by the Wanganui Round Table organisation over a series of weekend working bees, the new aviary took 2-3 years to complete.

The revolving entry to the aviary.

The major difficulty encountered was finding a workable technique to fix the irregular shapes of wire mesh together, and to adequately support the aviary’s framework.  Eventually, extensive welding of the wire mesh joints saw success achieved.  Rotating mesh doors were designed and fitted at either end to keep the birds enclosed.  Security cameras and an aviary extension came about two decades later.

The Wanganui Round Table Group was awarded the Community Service Rosebowl in 1979 for its contribution towards the new Virginia Lake aviary.

Similar ‘free-flight’ cages are now installed at various parks and wildlife facilities worldwide, and house both birds and animals.  Structures such as the free-flight enclosures at Otorohanga and Brooklnads Zoo in New Plymouth provide a unique visitor experience, and an enhanced home for wildlife that is as ‘natural’ as possible for an exhibit enclosure.  The free-flight aviary at Hamilton Zoo is the second largest enclosure of its kind in the world.

The present Virginia Lake aviary is not the first to have been erected at the reserve.  Two earlier aviaries entertained visitors, with the earliest dating back to 1942.  Many readers will remember the aviary that pre-dated the current one – a five-section facility similar to aviaries still in use at the Victoria Esplanade Park in Palmerston North, among other places.  This second Virginia Lake aviary stood between the Winter Gardens and the carpark, and when opened in 1960 was home to 60 birds.  Council records contain many letters of thanks to local residents for donations of aviary birds, including finches, canaries and parakeets.  There was even for many years a kea amongst the collection – before rules about keeping native birds changed.

Aviary interior.

The first Virginia Lake aviary was a gift from Mr and Mrs Larsen of Foster’s Hotel (now Stellar) in 1942, as an attraction for children to complement the recently completed Centennial Memorial Winter Gardens, which opened in 1940.  The Larsens owned ‘a very nice aviary of original design’ with 12 birds which they were unable to take with them when they left the city that July.  The only stipulation the Larsens made was that the birds must not be sold or given away to be put in small cages.

The mayor and council of the time gratefully accepted the gift, and arranged for the structure to be moved onto a concrete base at the lake reserve.

Keeping caged birds and animals is a very old tradition in many cultures.  Maori were known to keep tui in cages and to teach them to ‘talk’, and Victorian England had a well-known fscination with zoology and natural things.  The bird cage at Rotterdam Zoo was the largest zoo aviary when built in 1880, though the Flight Cage built for the Louisiana Purchase Exposition in Saint Louis in 1904 was larger (at 70m long, 25m wiude, and 15m high).  It remains one of the largest free-flight aviaries in the world today.

The immersion zoo exhibit, similar to the walk-through aviary in concept, was first developed by Carl Hagenbeck in 1907, and was revived and expanded following the opening of a ground-breaking goirilla exhibit at the Seattle Zoo in 1975.  Hagenbeck (1844-1913) began collecting animals at 14, and later exhibited humans (including Nubians, Samoans and Inuits) as well as animals in ‘natural’ settings in his zoos.  Hagenbeck’s ‘naturalistic exhibit’ idea – though fortunately not his taste for human exhibits – is now common practices in zoos worldwide.

© Karen Wrigglesworth and Geeky Getaways, 2011.

Aircraft hangars two and three at Ohakea were constructed between 1938 and 1939, and their design is replicated in similar structures at Whenuapai air base in Auckland (with modifications for lower-strength Auckland soils), and in Karachi (Pakistan) and Hyderabad (India).  Designed by chief design engineer CWO Turner of the Public Works Department, the hangars each have huge two-hinged arches supporting reinforced concrete roofing – a relatively new innovation at the time.

Even the hangar doors were constructed of concrete.

Ohakea hangar in operation

The hangars at Ohakea span 67m in width and are almost 20m high.  By comparison, the three-bay Brabazon Hangar at Bristol’s Filton Aerodrome was at the time of its construction (only a year later, in 1940) the largest hangar in the world.  The Brabazon hangar measures an impressive 350m in length by 35m high by 80m in width.

An important consideration for the designers at Ohakea was  the size and strength of the new structures.  Turner worked with cardboard models as part of the design process to ensure internal space was efficiently and appropriately allocated.

Most hangars are built of metal, although wood and concrete are sometimes used.  The word ‘hangar’originates from a French dialect word for cattle pens, though I’m not sure the Ohakea pilots would appreciate the inference that their aircraft are old cows!  The word actually refers to the cattle pen French pilot Louis Bleriot used to store his crashed monoplane in northern France in 1909.

The ohakea hangars were designed specifically to house 30 long-range Wellington bombers (which in the end never arrived, being donated instead to the RAF on the outbreak of WWII).  They also needed to be able to withstand bomb splinters in case of enemy attack.  The hangars were in the end never tested by a bombing attack, although one hangar at Whenuapai proved its strength by surviving an aircraft crash during the war – with only minimal damage incurred.

The Ohakea Base at Bulls

The decision to build the Ohakea hangars to a reinforced concrete design came after in-depth consideration of a variety of alternatives, including steel and ferroconcrete designs.  The final decision came down to availability, with structural steel (unlike the alternatives) able to be sourced without delay in the quantities required.

The Ohakea hangars were the first of their type to be constructed in New Zealand.  Although similar monocoque, or single shell (from the French) structures had been built in NZ before the 1930s, they had typically been built of steel, rather than concrete.  The concrete reinforced variants built at Ohakea were a novel innovation.

Reinforced concrete monocoque structures are strong and robust, qand provide a large clear space (no central support pillars) for storage beneath.  They support the structural load through the structure’s external skin (roof) rather than by using an internal truss (fram) or posts with a non-load-bearing skin on top.

Hangar and control tower

Monocoque construction is used in areas as diverse as architecture, car and aircraft manufacture, small boat construction (such as kayaks), and for motorbike frames.  Monocoque construction was first widely used in aircraft in the 1930s.

For the Ohakea hangars, each concrete pour had to take place in one operation.  Formwork (into which the concrete was poured and which created the final shape required) was initially paper over wood.  However, the paper stretched when wet, leaving patterns on the concrete, and so eventually plain timber formwork was used instead.

The Ohakea hangars were reroofed with steel in the 1990s, and also underwent strengthening work at that time.  Despite their age, they continue to serve their purpose, as well as providing an iconic backdrop to a strategic airforce base.

© Karen Wrigglesworth and Geeky Getaways, 2011.

Sarjeant Gallery undergoing skylight upgrade 2009

Samuel Hurst Seager (1855-1933) was a master builder, town planner, and an important New Zealand architect.  His 1885, competition-winning Queen Anne-style design for Christchurch’s municipal building established him as one of that city’s leading architects.  Seager later designed and lived at The Spur, Sumner (1902-1914) – a unique residential development of timber cottages in a garden setting.  Something people are today revisiting as a ‘modern’ idea.

Seager was an international authority on the lighting of art galleries, and in 1912 began discussion on the top side lighting method for galleries through the publication of an influential article.  He was assessor for the Wanganui and Christchurch art gallery competitions (1916 and 1929).  Entrants for the Wanganui competition were asked to incorporate this lighting method into their designs.

The Wanganui gallery competition was won by 21-year old Donald Hosie of the Dunedin firm Edmund Anscombe and Associates, who displayed both strong understanding and innovative implementation of Seager’s lighting ideals.  Hosie tragically didn’t live to see the gallery completed in 1919 – he was killed two years earlier at the battle of Passchendaele in France.  Hosie’s design for the Sarjeant Gallery included lighting ideas that were highly novel for the time.

A painting bay, gallery interior.

The gallery corridors are designed specifically so that visitors traverse areas of lower light compared to the well-lit back walls of each lofty picture bay.  There was an element of ‘moral uplifting’ to the design philosophy – of being ‘enlightened’ through art from a position of relative ignorance (and darkness), in life and in the corridor.  Lighting was originally pure daylight, entering through clear glass panels to simulate the experience of viewing the art out-of-doors.

The skylights were precisely designed to emit light at an angle of approximately 45 degrees to wall surfaces.  This meant that reflected images of the sky, of pictures in opposite bays, and of viewers themselves, would bounce off a painting’s glass out of the viewer’s sight.

Collections/building manager at the Sarjeant, Dennis Rainforth, tells me that the skylights used to be quite literally sky lights, transmitting into the gallery interior the changing character of the sky outside.  Modern art lighting requirements and earthquake standards have, however, seen installation of translucent laminated panels - installed in 2009 to replace translucent Duralite that had reached the end of its life.

The first two bays on each side of the central gallery dome are scaled for larger pictures, and the third space for medium sized pictures.  Seager had not intended that pictures should be hung on the side walls of each bay.

Skylight detail

Christopher (Kit) Cuttle, a lighting engineer, has provided advice over a number of years on the unique lighting design at the Sarjeant Gallery, as well as the gallery design information in several publications.

Lighting engineers design lighting systems (incorporating both natural and artificial light sources) for retail outlets, monuments, offices and sports venues, among other facilities.  They generally have a good understanding of the complexities of both electrical systems and architectural design.  In a gallery, lighting engineers have to balance a need to illuminate art with a requirement to reduce lighting levels to minimise artwork degradation.  Mathematical modelling is normally used these days for detailed lighting design.

Denis explains that current standards recommend a light level of 50 lux for a watercolour, or 150 lux for an oil painting.  By comparison, lighting levels in the side bays at the Sarjeant are in the order of 250 lux (now that the skylights are partially obscured).  IN the dome area, where the skylights are still clear, light can reach around 20,000 lux on a sunny day.

“Lighting can vary enormously, and can have a profoundly different effect on the experience of viewing a painting, Denis says.  “The challenge for us is to provide a balance between art preservation and the opportunity for patrons to experience Seager’s unique lighting principles in action.”

© Karen Wrigglesworth and Geeky Getaways, 2011.

Kawiti was uncle and ally to the notorious Hone Heke of flag chopping fame.

The design and construction of fortified pa in New Zealand follows interesting  patterns of evolution from the pre-European times of hand-to-hand combat to the post-colonial period of artillery warfare (which at that time included the use of muskets, cannons, mortars and rockets).

Sited on a strategic crest just south of Kawakawa, Ruapekapeka was Kawiti’s finest and strongest fighting pa.  It sits on an elevated sloping site, and occupies a large area of land for a pa of that time (150m by 70m).

Although not the first pa to incorporate trenches or palisades, it was a significant improvement in pa design for its innovative combination of the two.

Pa were traditionally sited on strategic hilltops that afforded a high degree of warning and protection from enemy groups, to guard tribal boundaries, important communication networks (tracks, waterways or coastal routes) or gardens.

What made Ruapekapeka significant – apart from combining trenches and palisades in one design – was its location away from areas of tribal importance.  It was Ruapekapeka’s isolation that gave it its strength.

Not only could it be abandoned without the loss of an important tribal asset, being inland also meant it was well away from colonial sources of supply and naval artillery firepower.

Ruapekapeka (or bats’ nest, for the way its defenders hid themselves in the dark underground) was surrounded by two rows of 3m to 5m-high palisades of puriri (ironwood) tree trunks and split timber lashed together and reinforced with flax.  Between the palisades lay a 2m-wide trench where defenders could hide and fire downhill at the colonial advance.  Although the timber has long gone, the deep ditches still show the original outline of the fortification.  Pa defenders were well protected.

Ruapekapeka today looks like a giant rabbit was let loose – there are tunnels and burrows and bunkers scattered all across the site, as well as neat trenches running downhill with protective abutments projecting into them from alternate sides to protect marksmen.

Many of the bunkers were originally covered with raupo huts, and tunnel roofs were supported by sturdy puriri beams.

With its numerous trenches, tunnel networks and burrows, Ruapekapeka Pa was far better able to handle cannon bombardment than its traditionally-designed predecessors.

Many of the bunkers are now filled with water but during my family’s visit we found an empty one that curved into a snug hole like the end of a Christmas cane.  A simple, ingenious design that gave the impression of a tunnel rather than a dead-end.

Although the pa was eventually taken (after being abandoned) and razed by the colonial forces (a 12-day seige by 1000 British troops and 40 allied Nga Puhi – against 400 to 500 of Kawiti’s men), Ruapekapeka’s strategic success sowed the seeds of change for both sides.  Its design was taken up and further developed by other tribes around NZ over the next 30 years.  Its strategic design also impressed the British enough for them to survey it twice, have a scale model of it built for teaching purposes, and for its anti-bombardment techniques to be emulated in trench warfare and bomb shelters right up until WWII.

In February 2008, a plaque was unveiled by representatives of IPENZ (NZ’s engineering organisation), the Ruapekapeka Pa Management Trust and the Department of Conservation to celebrate the engineering skills of the Maori who designed and built the fortification.

This is the first Maori site to be honoured in this way.

Ruapekapeka Pa was the final battle in the Northern War and, although neither side could claim a victory (the British suffered 45 casualties and the Maori about 30), it led to peace in the north for over a decade.

Sources: DOC, Elsdon Best, Neil Finlay, Nigel Prickett, WJ Phillipps, Belich, Hocken Library.

© Karen Wrigglesworth and Geeky Getaways, 2011.

In the midst of New Zealand’s North Island lies a clever little spiral of railway line - a soultion dreamed up by an engineer with a creative turn of mind by the name of Robert Holmes.  The track passes through a pair of tunnels before spiralling back on itself to pass over the top of one the tunnels and on up the incline.  The spiral provides a unique solution to the tricky problem of rapidly fluctuating levels that rail – unlike roads – cannot easily manage.  

Steam train ascending the Spiral, early 1900s

New Zealand’s rail network was constructed at an incredible pace and within a relatively constrained budget.  Most construction was carried out by hand, with oxen, horses and small steam trans carting heavy materials like stone and track to site.  By 1870 only 74km of line had been built (all in the South Island), but by 1880 some 1891km of track was in operation throughout the entire country.

The first sod on the North Island Main Trunk Line was turned near Te Awamutu on 15 April 1885.  By 1907 the 680km line was completed and in operation – apart from a 39km gap between Raurimu and Ohakune, where a horse-drawn coach service operated between the two towns.  It would be 23 years (from 1885) before the difficult central North Island portion of the route was completed. 

The clever spiral of railway at Raurimu, between National Park and Taumarunui, is one of New Zealand’s most famous engineering features.  It incorporates two tunnels, three horseshoe curves and a complete circle of track to achieve the required rise of 132m over a straight line distance of only 2km (4.5km of track). 

Between Taumarunui and National Park the Main Trunk Line covers about 18km and climbs about 635km.  But over the last 4.5km south from Raurimu, the altitude increase is about 215m.

Plan of Raurimu Spiral

Spiral designer Robert Holmes was educated in London and arrived in New Zealand in 1871.  He developed the final innovative design after many other engineers had scratched their heads over a workable solution  – one that didn’t require the tedious traditional stop-and-reverse arrangement for steep sections of track.  Holmes was later to become Engineer-in-Chief of the NZ Works Department, and was also involved with the scouting work for another of New Zealand’s internationally renowned feats of engineering – the road to Milford Sound.

The Main Trunk Line celebrated its centenary in 2008.

© Karen Wrigglesworth and Geeky Getaways, 2011.

But for me, the tunnel and elevator provide a unique and memorable Alice-in-Wonderland experience.  

Originally proposed by the local newspaper editor of the time, John Ball, and his friend Edward Crow, the elevator-and-tunnel concept seems to have been modelled on the street elevators of Lisbon, Portugal.  What makes the Durie Hill elevator unusual, however, is that it runs inside a shaft drilled through the hill itself.

Work on the Durie Hill tunnel began in 1916, during WWII.  The original entrance was buried in a landslide soon after work started, but the new tunnel alignment was completed without further incident.  The tunnel stretches 205m into the hillside, and the walls have been curved and lined with 2500 tonnes of reinforced concrete to support the weight of the hill above.

After the tunnel was shaped, the elevator shaft was dug first from the tunnel end and then from the top of the hill.  The vertical shaft lining was moulded on the ground at the top of the hill before being lowered down the shaft into position.  Not an easy task in the days before mechanised equipment, laser levels, and readi-mix concrete!

A 9.7m high flat-topped tower sits over the elevator shaft, houses the operating mechanism, and is the elevator’s hilltop terminus.  You can climb the ornate wrought-iron spiral staircase for a stunning 180 degree view of Wanganui city out to the coast on a clear day.

The elevator was originally powered by the tramway electricity supply of 500 volts DC.  I am told that the supply was turned on in the morning and off at night in those days, and that once, when the switchman slept in and was late for work, everyone else waiting for the tram or the elevator was late that morning, too!

The elevator’s (and the tramway’s) electricity supply was at first converted by large rotary converters at the Wanganui Power Station, but these were too big to be used economically for the elevator alone once the tramway closed.

From 1951 a mercury arc converter, adjoining the tower, has converted the 230 volt AC current from the national grid

The elevator was officially opened to the public on August 2, 1919.  The original fares were 4d up and 2d down for adults, and 3d up and 1d down for children.  A 12-trip discount fare was available for one shilling.

QUICK FACTS:

Where to find: Through the Maori gateway on Anzac Parade, opposite the city bridge which leads to Victoria Avenue, Wanganui city.  The hillside staircase is adjacent.

Open: Everyday except Christmas Day (December 25).

Cost: Tunnel – free; Elevator – small charge.  Pay the lift operator on board.

Engineer to project: E Crow.

Borough engineer: NC Staveley.

© Karen Wrigglesworth and Geeky Getaways, 2011.