The Gateway Bridge was developed as an additional crossing of the Brisbane River, to cater for traffic growth well into the 21st century. In the late 1970s, approximately 180,000 vehicles used the Captain Cook and Story bridges to cross the river each day. As the bridges began to approach capacity, the Queensland Government highlighted the need for an alternative crossing.
In 1978, the Queensland Government called for tenders to finance, design, construct, operate and maintain a tunnel or bridge and associated approaches across the Brisbane River. A site between Eagle Farm in the north and Queensport in the south (now known as Murarrie) was identified.
This location was chosen to service the industrial areas in the eastern section of the city, as well as Brisbane Airport and the port facilities at Fisherman Island. The Bridge would also form part of the city bypass for traffic destined for the Pacific and Bruce Highways.
In June 1980, the contract was awarded to Transfield (Qld) Pty Ltd to complete the project. Construction on the Gateway Bridge commenced on 5 June 1980.
The Bridge owes its distinctive shape to air traffic requirements restricting its height and shipping needs for navigational clearance - providing a narrow envelope in which to construct a 1.5 kilometre bridge.
The Gateway Bridge is 64.5 metres high and stretches 1.63 kilometres across the Brisbane River, with its main span 260 metres long.
Engineering and unique construction
The Gateway Bridge was heralded an engineering triumph of the time. At a cost of $140 million, it was a substantial investment for Queensland taking six years to construct.
Usually projects of this size were completely designed and then constructed. The Gateway Bridge was built on a fast track system, allowing the foundations to be constructed before designers commenced the final design of the girders. This system is estimated to have saved at least two years in construction time and, as a result, the Bridge was commissioned five months ahead of schedule.
Engineers and designers met the challenge of constructing a bridge below 80 metres but above 55 metres to meet air traffic and shipping navigation requirements. Long viaducts with tall piers were needed to achieve these requirements, ensuring that the maximum approach grade of 5.27% was met to suit traffic needs.
At its highest point, the Gateway Bridge is 64.5 metres above the Brisbane River, the equivalent of a 20 storey building.
The balanced cantilevers in the centre spans of the Gateway Bridge were cast in place using reusable formwork. The formwork was hung off a frame which enabled the builders to reposition it after the concrete had set in each section. This method of construction was the first of its kind.
Once completed, the Gateway Bridge boasted the longest cantilevered box girder main span in the world, measuring 260 metres point-to-point. It also had the highest load stressing cables in the approach spans in Australia, with 2200 tonnes of 12 millimetre stressing strand. Other feats at the time included bridge bearings with a maximum tested load of 4300 tonnes - the largest pot bearings made in Australia - and an erection truss weighing 650 tonnes.
Official opening
On 11 January 1986, 100,000 people streamed onto Brisbane's spectacular Gateway Bridge for the official opening and to walk over the bridge for the first time.
The crowd stretched for two kilometres and enjoyed champagne breakfasts, hot air balloon and helicopter viewing rides, vintage cars, fashion parades, live entertainment and over 100 stalls on the bridge.
This historic event is the only time that the entire bridge has been closed to vehicle traffic.
Traffic
When the Gateway Bridge officially opened to traffic, 12,500 vehicles travelled across it daily. By the end of its first year, this figure had grown to more than 17,000.
Today, more than 100,000 vehicles travel across the bridge each day.