Air Traffic Control Tower, Wellington Airport
Wellington, New Zealand
Set on a challenging site with poor founding soils and exposed to very high prevailing winds, high seismic loads and possible tsunami inundation, the tower is a critical post-disaster Importance Level 4 (IL4) facility - a vital piece of infrastructure in the event of a disaster, meeting Life Safety objectives in a 2500 year hazard event and Business Continuity objectives in a 500 year hazard event.
The new tower is located in a highly active seismic zone, dramatically highlighted in the 2016 earthquakes that damaged or destroyed a number of nearby structures. The tower’s proximity to the coast also means it may be subject to tsunami events and these two factors have informed very onerous performance criteria for the new building, befitting its designation as a critical post-disaster Importance Level 4 (IL4) facility.
These twin, but highly different, extreme load cases informed a unique composite structure, with concrete blade walls at lower levels supporting a concrete-filled CHS frame structure above, carrying the 360-degree operations cabin, all sitting on a base-isolation system. As well as offering seismic protection, this arrangement allowed far greater freedom to consider more dramatic architectural forms, a key requirement for a building that simultaneously represented both reconstruction and resilience. The base isolation solution permitted savings in the raft slab foundation and was achieved at no additional cost to the project.
In Wellington’s extreme conditions, the tower is designed to stand the test of time and serve as a core piece of recovery infrastructure in the event of disaster. With the base isolation, wind and tsunami protection, this is a robust, resilient building that provides a striking and memorable design for the local community, with a distinctive ‘lean’.