Toowoomba Obelisks

 Four Adelaide Black granite Obelisks in Ruthven Street ,Toowoomba supplied and installed by J.H. Wagner & Sons.

Toowoomba City Council's main street revitalisation programme 2002-2003 incorporated a budget for the inclusion of public artwork.  A successful submission by artist's team Stephanie Outridge Field and Stephen Hart proposed a series of four inverted, tilted and rotated, 7 metre high solid granite obelisks.  

The artists contracted engineer Jack Wade of Wade Consulting Group and Michael Wagner of J.H. Wagner & Sons Master Stone Masons during the design process to look at the engineering, manufacturing, installation and feasibility.  Careful investigation allowed the concept design to be planned with tie down fixing methods, processing and construction requirements.

Each obelisk has seven sections of one metre high solid Australian Black granite.  From the 600mm square base stone the obelisk sections taper to 1,000mm square at the top stone.  In addition to being inverted, the task of supplying each obelisk was made more complex due to the designed lean of 4.73 degrees over the seven metre height.  From top to bottom this lean equates to about 990mm out of plumb and is emphasised in the rotational placement of the four obelisks, each leaning in an alternating direction to the next obelisk.  The overall weight of each granite obelisk is 13,500 kilograms with the top stone weighing almost 3,000 kilograms and the bottom stone only 1,200 kilograms.

A series of holes were cored in each granite block to accommodate 316 grade stainless steel tie down rods.  The bottom face of the second to seventh blocks were also cored out to accept and cover specially manufactured tie down and joiner type nuts.  The nuts used are a large, 125mm long and 63mm diameter.  All fixings were concealed withing the granite blocks, allowing each block to be tied down and grouted with non-shrink grout.

During the processing each seven piece obelisk was processed as one unit and required machine modifications to accommodate the seven metre size.  Floor slabs under one of the granite polishing machines were removed and re-installed with a sloping floor to allow for the tapered sides, thus allowing level polished of each side of the obelisk at rotated stages.  Special lifting equipment was incorporated for each stone, allowing for lifting and then placement to be completed at the correct tilt angle without the need to adjust cranage on site.

Three of the total four obelisks were completed in early March 2003 and the final obelisk was installed in May in conjunction with other Council works in the Ruthven Street upgrade.  One-site installation of the completed obelisks required only eight days.

These polished granite icons have become yet another product feature for J.H. Wagner & Sons' extensive street scape range which already includes granite paving, walling products, fountains and many other products manufactures in wide range of natural stones with ease, creativity and flair.

Toowoomba City's Obelisks

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