Melbourne CityLink

Qualifying as Australia’s largest infrastructure project at the time of its completion in 2000, Melbourne CityLink involved more than 46 kilometers (29 miles) of new and modified structures, including new highway tunnels, new elevated freeways, and improvements to existing freeways.

At the heart of this enormous project was the Southern Link, which included the 3.2-kilometer (2 mile) Burnley Tunnel and the 1.4-kilometer (0.9 mile) Domain Tunnel. These twin, three-lane, horseshoe-shaped highway tunnels are 20 to 60 meters (66 to 197 feet) below ground surface and cost AU$500 million and AU$300 million, respectively. They comprise a segment connecting two existing freeways beneath suburban and city residential areas, sports facilities, the Yarra River, and Melbourne’s Royal Botanic Gardens.

On this design-construct project, Jacobs Associates provided tunnel design services as part of the Hyder design team throughout preliminary and final design, and construction phase design services to Transfield/Obayashi Joint Venture, the construction contractor. The tunnels were driven through mixed rock conditions with roadheaders on five different drives using a top heading and bench excavation sequence. Temporary support included ground freezing, pipe-spiling, steel sets, rock bolts, and anchor cables. Permanent support for the tunnels required both drained and undrained tunnel cross sections using unreinforced concrete placed within a waterproof membrane.

The CityLink project was delivered under a build-own-operate-transfer arrangement with the Victorian state government. Transurban, a publicly traded company on the Australian Stock Exchange, won by tender the concession from the Victorian Government to operate the Melbourne CityLink as a toll road for 34 years, with ownership then returning to the state. The entire project concluded with a total contract value of AU$2 billion. Melbourne CityLink now connects three existing freeways.