The first physical iteration of a challenge that will confront a number of Melbourne's top end builders has appeared on the Melbourne skyline. Traditionally the work of luffing cranes, a top slewing tower crane has appeared on Brady Group's Vision Apartments project directly opposite Victoria Market.
With few if any top slewing tower cranes reaching such heights in Melbourne previously, the Potain unit is a direct response to Melbourne's ever increasing tower heights and the impact they have upon protected aviation airspace.
The different style of crane allows the same functions to be performed, albeit with considerably less penetration into the skies above Melbourne.
The issue of aviation zones and built form overlapping one another has emerged as an issue for a number of Melbourne projects of late.
Covered previously on Urban Melbourne in articles by aviation consultancy specialist Ian Thompson and urban planner Nicholas Harrison, the dual prong issues of PANS-OPS and OLS have combined to both limit the height of proposed towers in Melbourne's CBD in particular and to also adjust the methods in which builders can deliver skyscrapers.
There are two types of prescribed airspace, an obstacle limitation surface (OLS) and PANS-OPS surface. It is important to emphasise that a planning permit granted by DTPLI does not enable a building to enter the prescribed airspace around an airport. Separate approval must be gained from the Department of Infrastructure and Regional Development.Ian Thompson
In the case of Vision Apartments, Brady Group's luffing Favelle Favco would have strayed into protected airspace for an unacceptably long period of time, thus the need for a new unit to be assembled along the towers eastern flank.
Aviation issues aside Brady's Favelle Favco (which was operational until last weekend) would have continued to climb Vision's exterior, completed the necessary works and then gradually lowered itself down to a point where it would have been dismantled by way of a mobile crane.
As it stands the newly assembled Potain which has its base set upon the roughly level 60 setback will likely need an additional recovery crane to be assembled in order to remove it, creating additional time requirements and expense to the build.
Vision Apartments itself has only a handful of floor to be formed and poured prior to the structure being completed, with overall completion slated for approximately mid year.
Projects in the immediate vicinity such as Swanston Central, Lighthouse and Victoria One may well face the same challenges regarding obstacle penetration as has Brady with Vision Tower, given they are all within the 215-240 metre bracket. It's also likely that Brookfield Multiplex as the constructors of Melbourne's tallest building, Australia 108 which is in its construction infancy, will also need to consider the style of crane it employs as the tower over time approaches its ultimate height of 319 metres.