Sydney's Tallest Tower Built Using Top Down Construction

CURRENTLY under construction, Crown Sydney will be the city's tallest tower when it completes in 2021.

Located in Barangaroo - the former docks adjacent to Sydney's central business district - the 22 hectare (54 acre) area is being regenerated into a mixed-use neighbourhood featuring offices, retail, hospitality and a residential development at a cost of USD $4.4BN.

Above: A render showing the Barangaroo development (image courtesy of Crown Resorts).

Crown Sydney will be the tallest of the proposed buildings at 271 metres (890 feet) and will contain a casino and a hotel.

The total cost of the project is estimated to be upward of USD $740 million.

Above: An aerial photo of the Crown Sydney site in context (image courtesy of Barangaroo Delivery Authority).

The project is being built using top down construction, in which construction proceeds simultaneously in both upwards and downwards directions once a ground floor slab has been formed. 

Above: Top down construction allows for construction to proceed below and above ground at the same time (image courtesy of Gravity Low).

This reduces programme time, but also simplifies contaminant management - a key risk given the site’s past industrial use. Top down is a much less disruptive method in these circumstances, as only ground floor penetrations need to be covered by a tent.

Above: Construction workers wearing protective outfits while excavating the building's basement (image courtesy of Gravity Low).

Construction workers digging the basement wear protective equipment and are also aided by an advanced ventilation system.

As the site is adjacent to the waterfront, dewatering equipment lowers the local water table, allowing for the construction of three underground levels.

Above: Excavated material can be safely removed by a gantry crane (image courtesy of Gravity Low).

Meanwhile, excavated material is being safely removed using gantry cranes installed inside the containment tents and is transported to off site and disposed of safely.

You can learn more about the wider Barangaroo development in our "Skylines Transformed" documentary.