The Gateway WA Alliance was a consortium including Main Roads Western Australia (WA), CPB Contractors (formerly Leighton Contractors), GHD, AECOM and BG&E. Georgiou also had an 18 per cent share in the design and construction of the project.
The Gateway WA Perth Airport and Freight Access Project improved access to Perth Airport and relieved traffic congestion by providing grade separated interchanges. The project included the design and construction of 11 road bridges, seven underpasses, seven kilometres of noise walls and various other structures.
TeeRoff girders are the main structural elements of seven of the bridges and the remaining four bridges utilise precast concrete planks. Most of the bridges have curved edges, two of which are flared to accommodate single point urban interchanges (SPUI). The curved edges became major urban design features along with other Gateway and way-finding themes such as ‘sky ribbon’ and ‘earth wall’.
One of the SPUI bridges required top down construction for which durable and continuous flight auger piles were utilised and abutments clad with precast concrete panels consistent in appearance with the full height mechanically stabilised earth panels used extensively throughout the project.
The underpasses utilise trapezoidal precast concrete units, that were standardised within the project. Heights and details of spandrel walls and wingwalls were custom-designed for each underpass in relation to the pathways and complex road geometry.
Bath structures were required to exclude groundwater from roads lowered for the interchange at the end of the Perth Airport main runway. These continuously reinforced concrete structures are designed to stringent crack control criteria and lined with bonded waterproofing membrane. The pump station required to drain these bath structures is a substantial buried structure in itself.